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Slide 2: Air Sampling and Industrial Hygiene Engineering © 2001 CRC Press LLC
Slide 3: Air Sampling and Industrial Hygiene Engineering Martha J. Boss and Dennis W. Day LEWIS PUBLISHERS Boca Raton London New York Washington, D.C. © 2001 CRC Press LLC
Slide 4: Library of Congress Cataloging-in-Publication Data Boss, Martha J. Air sampling and industrial hygiene engineering / Martha J. Boss, Dennis W. Day. p. cm. Includes bibliographical references and index. ISBN 1-56670-417-0 (alk. paper) 1. Air—Pollution—Measurement. 2. Industrial hygiene. 3. Air sampling apparatus. I. Day, Dennis W. II. Title. TD890 .B66 2000 628.5′3′0287—dc21 00-048666 CIP This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431, or visit our Web site at www.crcpress.com Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. © 2001 by CRC Press LLC Lewis Publishers is an imprint of CRC Press LLC No claim to original U.S. Government works International Standard Book Number 1-56670-417-0 Library of Congress Card Number 00-048666 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper © 2001 CRC Press LLC
Slide 5: Preface Many have endeavored to make our outdoor environment cleaner and safer. The learning process that occurred showed us the limitations of our planet and also the sustainability of our ecosystem if given a chance. As a community, we learned about the water, the soil, and the air. We learned about the underground river that flowed to the surface lake. We learned about air currents that transported airstreams around our globe. We discovered the reality of plate tectonics and the ever-changing hydrogeological system. Using this knowledge, we continued to learn how to clean our environment and prevent further damage. Our science careers began with teaching and working on environmental issues. During that time our concern for 1 ppm benzene at an underground storage tank (UST) location was intense. Then as we learned more, we began to see what had been invisible to us before—the air in our factories, hospitals, schools, homes, and cars. We began to realize that environmental concerns and our accumulated knowledge on how to protect people and the environment was not being translated into knowledge about buildings in which people live and work. Many people routinely work in factories where exposure to hundreds of parts per million of benzene is commonplace. Six years ago we received a call from a farm family in the Midwest. For three generations they had farmed their land. Now their children, their farm animals, and they themselves were sick. A chemical storage fire had burned out of control and covered their land and homes with oily soot. Yet that spring they planted their fields and tried to live their lives as before. As the planting season progressed, farmers sickened in the fields. Upon returning to their homes, the sickness increased. The vehicles they used in the field became more and more contaminated. The farmers began buying old cars and abandoning them when they could ride in them no longer. Two combines were also abandoned. They left their homes, in some cases the original farm homesteads that had housed three generations. Planting was over and the hogs were farrowing. The animals were born deformed; the mother animals died. Eventually most of the animals sickened and were sacrificed. The farmers began looking for answers. Fall approached and with that the harvest. The farmers reentered the fields and became increasingly sick. What to do? Should they even harvest these crops? Should their children be sent away? Winter came—was it all in their imagination? The doctors and scientists they had contacted were without answers. Perhaps it would be better in the spring. Spring arrived, planting began, and the cycle continued. From somewhere, they were given our name. We arrived and began investigating. These farmers and their families had not benefited at that time from the collective knowledge available pertaining to fires and chemical dispersion. Particulates laced with chemicals can exit the periphery of a firestorm. The chemicals could remain intact or even recombine. Many chemicals can remain in our soil and water; after plowing with combines, these chemicals reenter the airstream and become available once again for us to breathe and carry home on our clothing. These farmers were carrying home the vestiges of chemicals we use as pesticides and herbicides. Chemicals that had changed in the fire became more toxic at lower levels. Chemicals were rendered more easily available by their current adsorption to airborne soil particulates. Upon entry of these particulates into their lungs, the new chemical mix offgassed and became biologically active. In the heartland of America, these farmers had unwittingly participated in an experiment in chemical warfare! v © 2001 CRC Press LLC
Slide 6: We decided then to write a book to open a dialogue on air monitoring, risk, and engineering—a book to show that collectively we as scientists and engineers need to develop an interdisciplinary approach to applying our knowledge. Before any art must come the science. Chapter 1 (Air Sampling Introduction), 2 (Air Sampling Instrumentation Options), and 3 (Calibration Techniques) present the current state-of-the-art techniques for air sampling. Chapter 4 discusses statistical analysis and relevance issues. In Chapters 5 (Chemical Risk Assessment) and 6 (Biological Risk Assessment), we discuss how air sampling and other environmental sampling are used to determine risk— risks of acute effect, chronic effect, and carcinogenic effect. Biological risk always has the added element of reproduction, as biologicals, unlike chemicals, can enlarge their numbers over time and distance from their source. We then turn our attention to Chapter 7 (Indoor Air Quality and Environments) and Chapter 8 (Area Monitoring and Contingency Planning). Once we know how to monitor potential risk, how do we evaluate our buildings, our city air, and all the places we live and work? What do we do in an emergency? Are there times as illustrated in Chapter 9 when we will need to use microcircuitry and remote monitoring? What about our workplaces as addressed in Chapter 10 (Occupational Health—Air Monitoring Strategies)? Finally we need to consider monitoring for toxicological risk (Chapter 11). If we find risk is evident, what tools (Chapter 12, Risk Communication and Environmental Monitoring) will be needed? This book is the start of an interdisciplinary look at many issues that in fact are just one—can we live and work in places that are healthy? Do we have the knowledge and resources to ensure that our hospitals and schools have clean air? Can we now build and maintain ventilation systems that do not foul over time? After World War I, Martha’s grandfather returned to work in a cement plant. He was having some trouble breathing after he inhaled mustard agent in the trenches of France. At the cement plant he dug into the earth at a quarry using shovels and eventually powered equipment. The dust swirled around him and coated his clothing. Every night he was racked with convulsive coughing. In the morning he felt better, could even smoke on the way to work. Over the next 30 years, he slowly died. No one knew then to tell him—get another job, quit smoking, protect your damaged lungs. Dennis’s father was a plumber. He watched pipe fitters carry buckets of gray slurry to the work site. The slurry was applied to pipe junctures and hardened to ensure pipe integrity. The pipe fitters used their hands and wiped the excess slurry on their clothing. They returned home, where their clothes were washed with their family’s clothes; often the laundry room was next to the air intake for their home furnace. Over the years Dennis’s father watched all these men die as their lungs, scarred with asbestosis, failed. How many men and women to this day still do not know that the factories and workplaces they occupy are poisoning them and often their families? Do they not know because the knowledge is unavailable? No. However, we have been slow to realize the need to communicate our knowledge. The simplest concepts have been lost. You do not have to die to work. Ventilation systems can be improved. Healthier workers are more productive workers and happier people. As our buildings age, and as we use ventilation systems designed to heat buildings— and to cool them—our indoor air problems have multiplied. The heat and cool cycles often cause condensation within the air-handling systems. The fiberglass duct liners that have captured particulates become slightly wetted. With time molds and fungi begin their life cycles hidden from us and amplify in number. Their spores ride the duct’s airstream to our rooms and hallways. Maintenance personnel cannot reach the biological hiding ground. © 2001 CRC Press LLC
Slide 7: Our residents begin to notice their health decline. Biological risk? Yes. In our hospitals and schools? Yes. Our hope is that this book will be used to begin these dialogues. Engineers and scientists need to look holistically at building design and maintenance. Business people need to realize the financial risk associated with accepting a nice building front rather than a stateof-the-art ventilation system. We all need to begin talking and learning together, so that our children can live and work without concern for the very air that they breathe. Martha J. Boss Dennis W. Day © 2001 CRC Press LLC
Slide 8: About the Authors Martha Boss is a practicing industrial hygienist and safety engineer living in Omaha, NE and various airports throughout the United States. Many years ago, Martha won the Army Science award at the Des Moines, IA science fair. As fate would have it, Martha eventually worked for the Army and through the auspices of EPA grants was trained in industrial hygiene. All of this surprised Martha because she had intended to teach high school science and had prepared herself for that endeavor with a B.A. in biological education (University of Northern Iowa) and later a BS in biology (University of Nebraska). During Desert Shield that became Desert Storm, Martha was tasked under the War Powers Act to assist in the preparation of a western Army base to house and train special forces. Dennis was also so commissioned, and their professional association began. Martha worked with her fellow Army industrial hygienists and engineers to assess biological, radiological, and chemical warfare sites and find solutions. The Army continued her training at such institutions as Johns Hopkins, Harvard, and other top centers throughout the nation. After five years of traveling throughout the country to various very scary places, Martha decided to settle down in a regional engineering firm. After a couple of years, Martha realized she did not want to settle down and joined a national engineering firm where she is employed to this day. Martha is a principal toxicologist for URS Corporation and continues her practice as a certified industrial hygienist and certified safety professional (safety engineer). Martha is a member of the Hazardous Substances Research Center T3 board for Region 7 of the EPA, a diplomate of the American Academy of Industrial Hygiene, serves on the editorial advisory board for Stevens Publishing, and is a member of the American Industrial Hygiene Association and the American Society of Safety Engineers. Dennis Day is a practicing industrial hygienist and safety engineer living in Omaha, NE and various airports throughout the United States. Dennis began his career as a forester. For several years, he traveled through the forests of the East and South cruising timber. Then he decided to become a high school science teacher. Dennis used his B.S. in forestry (University of Missouri) to enable him to pursue additional studies in chemistry and biology (Creighton University) and become a professional teacher. After teaching for awhile Dennis was persuaded to join the Army Safety Office and ultimately the Omaha District engineering division. Dennis continued for ten years to work with various Army, EPA, and Department of Defense missions. His work included sites throughout the nation and in Europe. Dennis concentrated his efforts on streamlining site assessment protocols, community outreach with protective action plans for chemical warfare sites, and training industrial hygienists entering the Army work force. Eventually, Forrest Terrell of Dames & Moore (now URS) convinced Dennis to join that firm to develop an interdisciplinary industrial hygiene, safety, and engineering service to commercial and governmental clients. Dennis is a principal toxicologist for URS Corporation and continues his practice as a certified industrial hygienist and certified safety professional (safety engineer). Dennis is a diplomate of the American Academy of Industrial Hygiene and a member of the American Conference of Governmental Industrial Hygienists, the American Industrial Hygiene Association, and the American Society of Safety Engineers. In 1992 Dennis received the Achievement Medal for Civilian Service for his emergency industrial hygiene support following Hurricane Andrew. © 2001 CRC Press LLC
Slide 9: Contents 1 Air Sampling Introduction 1.1 Documentation 1.2 Sample Documentation 1.3 Competency for Sampling Technicians 1.4 Sampling Activity Hazard Analysis (AHA) 1.5 Security 1.5.1 Sample Containers—Laboratory 1.5.2 Sample Handling and Decontamination 1.5.3 Procedures for Packing and Shipping Low Concentration Samples 1.5.4 Procedures for Packing and Shipping Medium Concentration Samples 1.5.5 Chain-of-Custody Records 1.5.6 Mailing—Bulk and Air Samples 1.6 Equipment Precautions 1.6.1 Batteries 1.6.1.1 Alkaline Batteries 1.6.1.2 Rechargeable Nickel-Cadmium (Ni-Cad) Batteries 1.7 Adverse Temperature Effects 1.8 Explosive Atmospheres 1.9 Atmospheres Containing Carcinogens Air Sampling Instrumentation Options 2.1 Volatile Organic Compounds Photoionization Detector (PID) 2.1.1 2.1.1.1 Calibration 2.1.1.2 Maintenance 2.1.2 Infrared Analyzers 2.1.2.1 Calibration 2.1.2.2 Maintenance 2.1.3 Remote Collection 2.1.4 Oxygen/Combustible Gas Indicators (O 2/CGI)/Toxin Sensors 2.1.4.1 Remote Probes and Diffusion Grids 2.1.4.2 Calibration Alert and Documentation 2.1.4.3 Alarms 2.1.4.4 Recommendations for Oxygen/Combustible Gas Indicators 2.1.4.5 Relative Response 2.1.4.6 Relative Response and Toxic Atmosphere Data 2.1.4.7 Special Considerations 2.1.4.8 Calibration 2.1.4.9 Maintenance 2.1.5 Oxygen Meters 2.1.6 Solid Sorbent Tubes 2.1.6.1 Calibration Procedures 2.1.7 Vapor Badges 2 © 2001 CRC Press LLC
Slide 10: 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Detector Tubes 2.1.8.1 Performance Data 2.1.8.2 Leakage Test 2.1.8.3 Calibration Test 2.1.8.4 Special Considerations 2.1.9 Formaldehyde Ozone Meter 2.2.1 Calibration 2.2.2 Maintenance Toxic Gas Meters 2.3.1 Calibration Semivolatile Organic Compounds (SVOC) 2.4.1 Polynuclear Aromatic Hydrocarbons 2.4.2 Polychlorinated Biphenyls and Creosote 2.4.3 Pesticides and PAHs—PUF Acid Gases or Caustics 2.5.1 Impingers 2.5.2 Sorbent Tubes 2.5.3 Detectors 2.5.4 pH Litmus Paper or Meter 2.5.4.1 Calibration Mercury Analyzer—Gold Film Analyzer 2.6.1 Jerome Mercury Analyzer Survey Procedures 2.6.2 2.6.3 Precautions for Area Surveys 2.6.3.1 Calibration 2.6.3.2 Maintenance Particulates—Sampled by Filtration/Impaction Gravimetric Filter Weighing Procedure Total Dust and Metal Fumes Respirable Dust 2.10.1 Cyclones 2.10.1.1 Silica Respirable Dust—Cyclone Collection 2.10.1.2 Cyclone Cleaning Inhalable Dusts Personnel Environmental Monitors (PEMs) Welding Fumes Asbestos Direct-Reading Dust Monitors 2.15.1 Condensation Nuclei Counters (CNCs) 2.15.1.1 Calibration 2.15.1.2 Maintenance 2.15.1.3 Photodetection 2.15.1.4 Calibration 2.15.1.5 Maintenance 2.15.2 Diesel Particulate Matter (DPM) Biologicals 2.16.1 General Sampling Protocols 2.16.2 Contact and Grab Sampling 2.16.3 Reuter Central Fugal System (RCS) 2.1.8 © 2001 CRC Press LLC
Slide 11: 2.16.4 Exit Requirements 2.16.5 Static Placement Impingement 2.16.6 Bioaerosols 2.17 Radiation Monitors and Meters 2.17.1 Light Meter 2.17.1.1 Calibration 2.17.1.2 Maintenance 2.18 Ionizing Radiation 2.18.1 Ionization Detectors 2.18.1.1 Gas Proportional Detectors 2.18.1.2 Ion Chamber 2.18.1.3 GM Detector 2.18.2 Scintillation Detectors 2.18.3 Counting Efficiency 2.18.4 Monitoring for Radioactive Contamination 2.18.5 Daily Use Checks 2.18.6 Survey Instrument Calibration 2.19 Nonionizing Radiation 2.19.1 Guidance 2.19.2 Broadband Field Strength Meters 2.19.2.1 Calibration 2.19.2.2 Maintenance 3 Calibration Techniques 3.1 Calibration Requirements 3.1.1 Calibration Assurance 3.1.2 Decontamination 3.1.3 Maintenance 3.2 Manual Buret Bubble Meter Technique (Primary Calibration) 3.2.1 Bubble Meter Method 3.3 Electronic Flow Calibrators 3.3.1 Cleaning before Use 3.3.2 Leak Testing 3.3.3 Verification of Calibration 3.3.4 Shipping and Handling 3.3.5 Precautions and Warnings 3.4 Electronic Bubble Meter Method 3.5 Dry Flow Calibration 3.6 Precision Rotameter Method (Secondary) 3.6.1 Replacing the Bubble Meter with a Precision Rotameter 3.7 Span Gas 3.8 Bump Testing Statistical Analysis and Relevance 4.1 Definitions 4.2 Example—Outline of Bulk Sampling QA/QC Procedure 4.3 Example—Outline of the NIOSH 7400 QA Procedure 4.3.1 Precision: Laboratory Uses a Precision of .45 4.3.2 Precision: Laboratory Uses a Precision SR That Is Better Than .45 4.3.3 Records to Be Kept in a QA/QC System 4 © 2001 CRC Press LLC
Slide 12: 4.4 4.5 4.6 4.7 4.8 5 4.3.4 Field Monitoring Procedures—Air Sample 4.3.5 Calibration 4.3.6 Negative Air Pressure 4.3.7 Compressor 4.3.8 Recordkeeping and Sample Storage Sampling and Analytical Errors 4.4.1 Determining SAEs 4.4.2 Environmental Variables 4.4.3 Confidence Limits Sampling Methods 4.5.1 Full-Period, Continuous Single Sampling 4.5.2 Full-Period, Consecutive Sampling 4.5.3 Grab Sampling Calculations 4.6.1 Calculation Method for a Full-Period, Continuous Single Sample 4.6.2 Sample Calculation for a Full-Period, Continuous Single Sample 4.6.3 Calculation Method for Full-Period Consecutive Sampling 4.6.4 Sample Calculation for Full-Period Consecutive Sampling Grab Sampling SAEs—Exposure to Chemical Mixtures Chemical Risk Assessment 5.1 Baseline Risk Assessment 5.2 Conceptual Site Model Source Areas 5.2.1 5.2.2 Possible Receptors 5.3 Chemicals of Potential Concern 5.4 Human Health BLRA Criteria 5.5 Toxicity Assessment 5.6 Toxicological Profiles 5.7 Uncertainties Related to Toxicity Information 5.8 Potentially Exposed Populations 5.8.1 Exposure Pathways 5.8.2 Sources 5.9 Environmental Fate and Transport of COPCs 5.10 Exposure Points and Exposure Routes 5.11 Complete Exposure Pathways Evaluated 5.12 Ecological Risk Assessment 5.13 Data Evaluation and Data Gaps 5.14 Uncertainties 5.14.1 Uncertainties Related to Toxicity Information 5.14.2 Uncertainties in the Exposure Assessment 5.15 Risk Characterization 5.16 Headspace Monitoring—Volatiles 5.17 O 2/CGI 5.18 Industrial Monitoring—Process Safety Management 5.19 Bulk Samples Biological Risk Assessment 6.1 Fungi, Molds, and Risk 6.1.1 What Is the Difference between Molds, Fungi, and Yeasts? 6 © 2001 CRC Press LLC
Slide 13: 6.2 6.3 6.4 6.5 6.6 How Would I Become Exposed to Fungi That Would Create a Health Effect? 6.1.3 What Types of Molds Are Commonly Found Indoors? 6.1.4 Are Mold Counts Helpful? 6.1.5 What Can Happen with Mold-Caused Health Disorders? Biological Agents and Fungi Types 6.2.1 Alternaria 6.2.2 Aureobasidium 6.2.3 Cladosporium 6.2.4 Rhodotorula 6.2.5 Stemphylium 6.2.6 Sterile Fungi 6.2.7 Yeast Aspergillus 6.3.1 What Color Are These Molds? 6.3.2 How Is Aspergillus Spread? 6.3.3 How Does Aspergillus Grow/Amplify? 6.3.4 What Conditions Help Aspergillus Grow/Amplify? 6.3.5 Can Mold/Fungi Make You Sick? 6.3.6 What Are the Symptoms of Aspergillosis? 6.3.7 Does Aspergillus Cause Deterioration of Materials? 6.3.8 What Happens If Aspergillus Colonies Grow inside Construction Layers? 6.3.9 How Is Aspergillus Identified? 6.3.10 How Are Levels of Aspergillus Communicated? 6.3.11 Why Do Aspergillus Colonies Look Black? 6.3.12 What Will Biotesting of the Air Show? 6.3.13 What Can Be Done to Prevent Aspergillus Growth? Penicillium 6.4.1 What Do Samples Look Like? 6.4.2 What Species of Penicillium Are Used to Produce Antibiotics? 6.4.3 What Other Fungi Grow Where Penicillium Grows? 6.4.4 If Penicillium Grows Everywhere, What Is the Concern? 6.4.5 How Does Penicillium Enter the Body? 6.4.6 Are There Particular Species of Penicillium about Which I Should Be Concerned? Fungi and Disease 6.5.1 Blastomyces dermatitidis 6.5.2 Coccidioides immitis 6.5.3 Histoplasma capsulatum 6.5.4 Sporothrix schenckii 6.5.5 Pathogenic Members of the Genera Epidermophyton, Microsporum, and Trichophyton 6.5.6 Miscellaneous Molds 6.5.7 Fusarium Fungi Control 6.6.1 Ubiquitous Fungi 6.6.2 Infection 6.6.3 Immediate Worker Protection 6.6.4 Decontamination 6.6.5 Fungi and VOCs 6.1.2 © 2001 CRC Press LLC
Slide 14: 6.7 7 6.6.6 Controlling Fungi Abatement Indoor Air Quality and Environments 7.1 Ventilation Design Guide 7.2 Example Design Conditions Guidance 7.2.1 Outside Design Conditions 7.2.2 Inside Design Conditions 7.3 Mechanical Room Layout Requirements 7.4 Electrical Equipment/Panel Coordination 7.5 General Piping Requirements 7.6 Roof-Mounted Equipment 7.7 Vibration Isolation/Equipment Pads 7.8 Instrumentation 7.9 Redundancy 7.10 Exterior Heat Distribution System 7.10.1 Determination of Existing Heat Distribution Systems 7.10.2 Selection of Heat Distribution Systems 7.10.2.1 AG Systems 7.10.2.2 CST Systems 7.10.2.3 Buried Conduit (preapproved type) 7.10.2.4 Buried Conduit (not preapproved type) 7.10.3 Design of Heat Distribution Systems 7.10.4 Existing System Capacity 7.10.5 General Design Considerations Identification 7.11 Thermal Insulation of Mechanical Systems 7.12 Plumbing System 7.12.1 Piping Run 7.12.1.1 Back-Siphonage 7.13 Compressed Air System 7.13.1 Compressor Selection and Analysis 7.13.2 Compressor Capacity 7.13.3 Compressor Location and Foundations 7.13.4 Makeup Air 7.13.5 Compressed Air Outlets 7.13.6 Refrigerated Dryer 7.14 Air Supply and Distribution System 7.14.1 Basic Design Principles 7.14.2 Temperature Settings 7.14.3 Air-Conditioning Loads 7.14.4 Infiltration 7.14.5 Outdoor Air Intakes 7.14.6 Filtration 7.14.7 Economizer Cycle 7.15 Ductwork Design 7.15.1 Variable Air Volume (VAV) Systems 7.15.2 Special Criteria for Humid Areas 7.15.3 Evaporative Cooling © 2001 CRC Press LLC
Slide 15: 7.16 Ventilation and Exhaust Systems 7.16.1 Supply and Exhaust Fans 7.16.2 General Items 7.17 Testing, Adjusting, and Balancing of HVAC Systems 7.18 Ventilation Adequacy 7.19 Laboratory Fume Hood Performance Criteria 7.20 Flow Hoods 7.20.1 Calibration 7.20.2 Maintenance 7.21 Thermoanemometers 7.21.1 Calibration 7.21.2 Maintenance 7.22 Other Velometers 8 Area Monitoring and Contingency Planning 8.1 Area of Influence Perimeter 8.1.1 Evaluation of Hazardous Waste/Chemical Risk Sites Off-Site Characterization before Site Entry 8.1.2 8.1.2.1 Interview/Records Research 8.1.3 On-Site Survey 8.1.3.1 Potential IDLH Conditions 8.1.3.2 Perimeter Reconnaissance 8.1.3.3 On-Site Survey 8.1.4 Chemical Hazard Monitoring 8.1.4.1 Skin and Dermal Hazards 8.1.4.2 Potential Eye Irritation 8.1.4.3 Explosion and Flammability Ranges 8.1.5 Monitoring 8.1.6 Field Logbook Entries 8.1.7 Radiation Monitoring 8.1.7.1 Area Monitoring 8.1.7.2 Contamination Surveys 8.1.7.3 Exposure Rate Surveys 8.1.7.4 Personnel Monitoring 8.2 Evacuation Zones 8.2.1 Emergency Equipment Locations 8.2.2 Site Security and Control 8.2.3 Incident/Accident Report 8.3 Site Work Zone 8.3.1 Integrated Sampling Example 8.3.2 Field QA and QC Example 8.3.3 Invasive Work Sampling Example 8.3.4 Sampling and Initial Site Work Hazard Analysis Example 8.3.4.1 Perimeter Monitoring 8.3.4.2 Air Sampling and Monitoring Example 8.3.4.3 Water Sampling Example 8.3.4.4 Surface Soil/Sediment Sampling Example 8.4 Radiation Sites 8.4.1 Atomic Structure © 2001 CRC Press LLC
Slide 16: 8.4.2 8.4.3 8.4.4 8.4.5 8.4.6 8.4.7 8.4.8 8.4.9 8.4.10 8.4.11 8.4.12 8.4.13 8.4.14 8.4.15 8.4.16 8.4.17 8.4.18 8.4.19 8.4.20 8.4.21 8.4.22 8.4.23 8.4.24 8.4.25 8.4.26 8.4.27 8.4.28 Radioactive Decay Activity Decay Law Half-Life Types of Ionizing Radiation 8.4.6.1 Alpha Particles 8.4.6.2 Beta Particles 8.4.6.3 Gamma Rays 8.4.6.4 X-rays Rules of Thumb Excitation/Ionization Characteristics of Different Types of Ionizing Radiation Exposure (roentgen) Absorbed Dose (rad) Dose Equivalent (rem) Effective Dose Equivalent Biological Effects of Ionizing Radiation 8.4.14.1 Radiosensitivity Human Health Effects 8.4.15.1 Stochastic Effects 8.4.15.2 Nonstochastic Effects Determinants of Dose 8.4.16.1 External Exposures 8.4.16.2 Internal Exposures Sources of Exposure 8.4.17.1 Occupational Exposure 8.4.17.2 Nonoccupational Exposure Exposure Limits Basis of Recent Guidelines Regulatory Limits for Occupational Exposure Recommended Exposure Limits for Pregnant Workers Radiation Risk Philosophy of Current Radiation Safety Practice 8.4.23.1 Internal Radiation Protection 8.4.23.2 Protection against Ingestion 8.4.23.3 Protection against Inhalation 8.4.23.4 Protection against Absorption External Radiation Protection Minimizing Exposure Time Maximizing Distance from Source Shielding the Source Emergency Procedures 8.4.28.1 Personal Contamination 8.4.28.2 Minor Spills (Microcurie Quantities of Most Nuclides) 8.4.28.3 For Major Spills (Millicurie Quantities of Most Nuclides) 9 Microcircuitry and Remote Monitoring 9.1 Continuous IAQ Monitoring in Buildings 9.1.1 IAQ Evaluations 9.1.1.1 Characterization for IAQ Assessment © 2001 CRC Press LLC
Slide 17: 9.2 9.1.1.2 Source Assessment and Remediation 9.1.1.3 IAQ Risk Assessment Industrial/Remediation Process Monitoring 9.2.1 Process Safety Management Example Scope of Work 9.2.2 Provide List for Hazard and Operability Study 9.2.3 Process Hazard Analysis 9.2.3.1 Hazard and Operability Study 9.2.3.2 Failure Modes and Effects Analysis (FMEA) 9.2.3.3 Fault Tree Analysis 9.2.4 Design Analysis 9.2.4.1 Site Safety and Health Plans 9.2.4.2 Health and Safety Design Analysis (HSDA) 9.2.4.3 Drawings 9.2.4.4 Specifications 9.2.4.5 Design Analysis Example—Wastewater Treatment 10 Occupational Health—Air Monitoring Strategies 10.1 Exposure Measurements 10.2 STEL Sampling 10.3 Exposure Fluctuations 10.4 Air-Sampling Pump User Operation 10.4.1 Pump Donning 10.4.2 Pump Checking 10.4.3 Pump Doffing 10.5 Air Sampling—Asbestos 10.5.1 Sampling Prior to Asbestos Work 10.5.2 Sampling during Asbestos Abatement Work 10.5.3 Sampling after Final Cleanup (Clearance Sampling) 10.5.4 NIOSH Method 10.5.5 Air Sampling Documentation 10.5.6 Asbestos Exposure Monitoring (29 CFR 1910.1001 and 29 CFR 1926.1101) 10.5.7 Initial Monitoring 10.5.8 Historical Documentation for Initial Monitoring 10.5.9 Objective Data for Initial Monitoring 10.6 Crystalline Silica Samples Analyzed by X-Ray Diffraction (XRD) 10.6.1 Air Samples 10.6.1.1 Laboratory Results for Air Samples 10.6.2 Bulk Samples 10.6.3 Sample Calculations for Crystalline Silica Exposures 10.6.4 Sample Calculation for Silica Exposure 10.7 Metals—Welding 10.8 General Technique for Wipe Sampling 10.8.1 Filter Media and Solvents 10.8.2 Wipe Sampling Procedures 10.8.3 Special Technique for Wipe Sampling with Acids and Bases 10.8.4 Direct-Reading Instruments 10.8.5 Aromatic Amines 10.8.6 Special Considerations 10.8.6.1 Fluorescent Screening for Carcinogenic Aromatic Amines 10.8.6.2 Alternate Screening Methods for Aromatic Amines © 2001 CRC Press LLC
Slide 18: 11 Monitoring for Toxicological Risk 11.1 Types of Sampling 11.1.1 Long-Term Samples 11.1.2 Short-Term Samples 11.1.3 Area Samples 11.1.4 Wipe Samples 11.2 Quality Control 11.3 Exposure Evaluation Criteria 11.4 Examples of Chemicals That Require Monitoring 11.4.1 Carbon Monoxide (CO) 11.4.2 Hydrogen Sulfide (H 2S) 11.4.3 Sulfur Dioxide (SO 2) 11.4.4 Ammonia (NH3) 11.4.5 Benzene 11.4.6 Hydrogen Cyanide or Hydrocyanic Acid (HCN) 11.4.7 Lead 11.4.8 Flammable Chemicals 11.4.9 Reactive Hazards—Oxidizers 11.4.10 Paint 11.4.11 Cleaning Supplies 11.4.12 Compressed Gases 11.5 Confined Space Monitoring 11.5.1 Entry Permits 11.5.2 Bump Testing 11.5.3 Monitoring for LEL and O 2 Levels 11.5.4 Isolation 11.5.5 Confined Space—Cautionary Statements 11.5.6 Stratified Atmospheres 11.6 Welding 11.6.1 Effects of Toxic Gases 11.6.2 Ventilation 11.6.3 Ventilation in Confined Spaces during Welding 11.6.4 Fume Avoidance 11.6.5 Light Rays 11.6.6 Infrared Rays 11.6.7 Noise 11.6.8 Gas Welding and Cutting 12 Risk Communication and Environmental Monitoring 12.1 Federal Legislation 12.1.1 The Clean Air Act Amendments of 1990 (CAAA90) 12.1.2 The Federal Water Pollution Control Act. 12.1.3 Resource Conservation and Recovery Act (RCRA) of 1976 12.1.4 State/Local Regulations 12.2 Key Compliance Requirements 12.2.1 Steam-Generating Units [greater than 29 MW (100 MBtu/h)] 12.2.2 Steam-Generating Units [2.9 MW (10 MBtu/h) to 29 MW] 12.2.3 Fuel-Burning Facilities 12.2.4 Stationary Gas Turbines 12.2.5 Municipal Waste Combustor © 2001 CRC Press LLC
Slide 19: Incinerators 12.2.6.1 Sewage Sludge Incinerators 12.2.6.2 Beryllium Incinerators 12.2.6.3 Incineration of Sewage Sludge 12.2.7 Gasoline Dispensing 12.2.8 Rotogravure Printing Presses 12.2.9 Fugitive Emissions 12.2.10 Sulfuric and Nitric Acid Plants 12.2.11 CFCs and Halons 12.2.12 Degreasing Operations 12.3 Key Compliance Definitions 12.4 Community Relations 12.4.1 Notification 12.4.2 Fact Sheets 12.4.3 Explaining Air Monitoring to the General Public 12.4.4 Employee Education 12.4.5 Public Accessibility 12.4.6 Repository 12.4.7 Dialogue Glossary of Terms 12.2.6 © 2001 CRC Press LLC
Slide 20: CHAPTER 1 Air Sampling Introduction This chapter provides an overview of air sampling and site monitoring that is legally defensible. It answers questions about monitoring protocols that must be initiated for emergency and contingency situations. 1.1 DOCUMENTATION Essentially in any sampling endeavor, without documentation, you have what is called “personal opinion.’’ The intent of documentation is to provide the basis for professional opinion. The documentation then becomes a dialogue of historical perspective and the empirical sampling event. When assembling historical documentation, make sure that you define how the information is used. Often in order to understand sampling results, the environment, including work practices, must be analyzed. Work practices include human factors; therefore, you must be very careful to present a dialogue of these work practices that is not individually invasive. When you decide on documentation techniques, before you write the first chronicle, enter field notes, or take that first picture, make sure that everyone understands what the purpose of the information is and who will have access to this information. Be very careful when the original scope of work calls for only general information. Often as the investigation continues, you may be asked to provide very specific reasons for general information development. Consequently, even for general information screening or limited audits, you may need to keep very specific information available to substantiate your opinions. Whenever a review of human factors is required, especially interviews, all parties must understand the limitations on personal anecdotal information. If you do not intend to personally name the interviewee, make sure all parties understand. The overriding message here is define your scope of work and write this definition for all to see. If you need to work under the auspice of attorney/client privilege or through any other set boundaries, make sure the scope of work reflects these facts. 1.2 SAMPLE DOCUMENTATION To assist in determining appropriate engineering controls, take photographs (as appropriate) and detailed notes concerning the following: © 2001 CRC Press LLC
Slide 21: • • • • • Visible airborne contaminants Work practices Potential interferences Movements Other conditions Prepare blanks during the sample period for each type of sample collected. One blank will suffice for up to 20 samples for any given analysis. These blanks may include opened, but unused, charcoal tubes. 1.3 COMPETENCY FOR SAMPLING TECHNICIANS When deciding who is defined as a competent sampling technician, the first criterion is as follows: Is the scope of work completely defined according to sampling requirements? If you have any doubts about the situation with which samplers are involved, whether those doubts stem from a lack of background knowledge of the site or unknown hazards, the sampling scope is not completely defined. For undefined sampling scopes, a senior sampling professional will need to initiate the site work. If the sampling choices once in the field are multifactorial, in that circumstances on-site are very dynamic, a team of senior sampling professionals is required. Remember that a phenomenon known as perceptual shift will occur during sampling. As we become more or less secure with our environment, we start to see things differently. A strong team is able to keep its members on target, thus providing a more complete picture of the sampling environment. Once a scope of work is defined, sampling can often be delegated to less senior personnel. The purpose of this text is to provide information to assist in the standardization of both the initial and the delegated work effort. Despite the many ways of communicating before the sampling event, dialogue must be continued throughout the sampling event. Unfortunately this dialogue may not be free-flowing conversation without limitations. The original team that defined the scope of work must be available to the on-site personnel. The actual conversations on-site, while delimited by many events, must give way to freeflowing discussions within this team so that the collected data are useful and relevant. 1.4 SAMPLING ACTIVITY HAZARD ANALYSIS To analyze the activities involved in sampling, an Activity Hazard Analysis (AHA) may be required. An example AHA is given in Table 1.1. 1.5 SECURITY Whenever confidential or security issue data are collected, this information must be secured. One of the most difficult issues when on-site is just what to write down or record on media. Too much information is as bad as too little information. For the junior sampling technician, raw data should not be interpreted in the field without consultation with the scope development team. Usually this consultation will produce advice to the sampling technician; do not record that advice other than through a verbal discussion with senior staff. © 2001 CRC Press LLC
Slide 22: Table 1.1 Air Sampling and Monitoring Activity Air sampling and monitoring Hazards Electrical Recommended Controls • Grounded plugs should be used. • Generators or air pumps should be used in dry areas, away from possible ignition sources. • Do not stand in water or other liquids when handling equipment. • Electrical equipment will conform to OSHA 1910.303(a) and 1910.305(a),(f),(f)(3). • Ground fault interrupters are used in the absence of • Sampling pumps Ambient environment and readings properly grounded circuitry or when portable tools must be used in wet areas. Extension cords should be protected from damage and maintained in good condition. Air pumps should be placed within easy reach using an OSHA-approved ladder or elevated platform or by placing the pump on a stake. Personnel should be thoroughly familiar with the use, limitations, and operating characteristics of the monitoring instruments. Perform continuous monitoring in variable atmospheres. Use intrinsically safe instruments until the absence of combustible gases or vapor is anticipated. • • • • Samples should be handled only by workers specifically designated as samplers. The worker who signs the chain-of-custody record will guarantee sample integrity until its final arrival at the laboratory. 1.5.1 Sample Containers—Laboratory The analytical laboratory will often provide sample containers. The containers for soil or water sampling will be either high-density polyethylene or glass with Teflon®-lined lids and will be pretreated with preservatives as applicable. The type of sample containers and preservatives required for each analysis will be specified by the laboratory in coordination with the scope of work. Sample filter cassettes, sorbent tubes, and other collection devices for air samples may also be obtained for the laboratory. Coordination with the laboratory is essential to ensure that sample containers meet the laboratory’s internal quality control requirements as well as regulatory requirements. 1.5.2 Sample Handling and Decontamination After sample collection in the field, the exterior of sample containers will be decontaminated if gross contamination is present. The sample containers will be handled with gloves until they are decontaminated with a detergent wash and water rinse. Care will be taken to avoid damaging the temporary labeling during decontamination. After decontamination, permanent labels will be placed on clean sample container exteriors. © 2001 CRC Press LLC
Slide 23: The sample containers will be well cushioned with packing materials and packaged as described below for transportation to the laboratory. Care will be taken to seal bottle caps tightly. The samples will be shipped to the laboratory under chain-of-custody protocols. Asbestos samples should never be sent with packing peanuts because the static charge generated during shipping will alter the pattern of fiber deposition on the cassette filters. Volatile samples must be sent in cooling chests to maintain a 4°C atmosphere during shipment. Semivolatiles should also be sent in cooling chests. 1.5.3 Procedures for Packing and Shipping Low Concentration Samples Samples will be packaged as follows: • Use waterproof metal (or equivalent strength plastic) ice chests or coolers only. • After determining the specific samples to be submitted and filling out the pertinent information on the sample label and tag, put the label on the bottle or vial prior to packing. • Secure the lid with strapping tape (tape on volatile organic compound [VOC] vials may cause contamination). • Mark volume level on bottle with grease pencil. • Place about 3 in. of inert cushioning material, such as vermiculite, in the bottom of the cooler. • Enclose the bottles in clear plastic bags through which sample tags and labels are visible and seal the bags. Pack bottles upright in the cooler and isolate them in such a way that they do not touch and will not touch during shipment. • Place bubble wrap and/or packing material around and among the sample bottles to partially cover them (no more than halfway). • Add sufficient ice (double bagged) between and on top of the samples to cool them and keep them at approximately 4°C until received by the analytical laboratory. • Fill cooler with cushioning material. • Put paperwork (chain-of-custody record) in a waterproof plastic bag and tape it with duct tape to the inside. • Tape the drain of the cooler shut with duct tape. • Secure the lid by wrapping the cooler completely with strapping, duct, or clear shipping tape at a minimum of two locations. Do not cover any labels. • Attach completed shipping label to the top of the cooler. • Label “This Side Up’’ on the top of the cooler, “Up’’ with arrow denoting direction on all four sides, and “Fragile’’ on at least two sides. • Affix numbered and signed custody seals on front right and back left of cooler. Cover seals with wide, clear tape. 1.5.4 Procedures for Packing and Shipping Medium Concentration Samples An effort will be made to identify samples suspected of having elevated contaminant concentrations based on field observations and screening tests. These samples will be segregated and packed in a separate container to the extent allowed by prevailing field conditions. Lids for these samples will be sealed to the containers with tape. Medium © 2001 CRC Press LLC
Slide 24: concentration samples will be packed in the same manner as described for low concentration samples. 1.5.5 Chain-of-Custody Records Chain-of-custody protocols will be established to provide documentation that samples were handled by authorized individuals as a means to maintain sample integrity. The chain-of-custody record will contain the following information: • • • • • • • • • • Sample identification number Date, time, and depth of sample collection Sample type (e.g., sludge) Type and number of container Requested analyses Field notes and laboratory notes Project name and location Name of collector Laboratory name and contact person Signature of person relinquishing or receiving samples Chain-of-custody records will be maintained for each laboratory sample. At the end of each day on which samples are collected, and prior to the transfer of the samples off-site, chain-of-custody documentation will be completed for each sample. Information on the chain-of-custody record will be verified to ensure that the information is consistent with the information on the container labels and in the field logbook. Upon receipt of the sample cooler at the laboratory, the laboratory custodian will break the shipping container seal, inspect the condition of the samples, and sign the chain-ofcustody record to document receipt of the sample containers. Information on the chain-ofcustody record will be verified to ensure that the information is consistent with the information on the container labels. If the sample containers appear to have been opened or tampered with, this discrepancy should be noted by the person receiving the samples under the section entitled “Remarks.’’ The completed chain-of-custody records will be included with the analytical report prepared by the laboratory. 1.5.6 Mailing—Bulk and Air Samples Mail bulk samples and air samples separately to avoid cross-contamination: • Pack the samples securely to avoid any rattle or shock damage. Do not use expanded polystyrene packaging. • Use bubble sheeting as packing. • Put identifying paperwork in every package. • Do not send samples in plastic bags or envelopes. • Do not use polystyrene packing peanuts. • Print legibly on all forms. For exceptional sampling conditions or high flow rates, contact a Certified Industrial Hygienist (CIH) or the chosen analytical laboratory (approved by the American Industrial Hygiene Association [AIHA]). © 2001 CRC Press LLC
Slide 25: 1.6 EQUIPMENT PRECAUTIONS 1.6.1 BATTERIES 1.6.1.1 Alkaline Batteries Replace frequently (once a month) and carry fresh replacements. 1.6.1.2 Rechargeable Nickel-Cadmium (Ni-Cad) Batteries Check the batteries under load (e.g., turn pump on and check voltage at charging jack) before use. See the manufacturer’s instructions for locations to check voltage. Use 1.3 to 1.4 V per Ni-Cad cell for an estimate of the fully charged voltage of a rechargeable battery pack. It is undesirable to discharge a multicell Ni-Cad battery pack to voltage levels that are 70% or less of its rated voltage; this procedure will drive a reverse current through some of the cells and can permanently damage them. When the voltage of the battery pack drops to 70% of its rated value; it is considered depleted and should be recharged. Rechargeable Ni-Cad batteries should be charged only in accordance with the manufacturer’s instructions. Chargers are generally designed to charge batteries quickly (approximately 8 to 16 h) at either a high charge rate or slowly (trickle charge). A battery can be overcharged and ruined when a high charge rate is applied for too many hours. However, Ni-Cad batteries may be left on trickle charge indefinitely to maintain them at peak capacity. In this case discharging for a period equal to the longest effective field service time may be necessary, because of short-term memory imprinting (Figure 1.1). Figure 1.1 This battery maintenance system accommodates one to five rechargeable air sampling pump battery packs. (SKC) © 2001 CRC Press LLC
Slide 26: 1.7 ADVERSE TEMPERATURE EFFECTS High ambient temperature, above 100°F and/or radiant heat (e.g., from nearby molten metal) can cause flow faults in air sampling pumps. If these conditions are likely, use the pump with a higher operating temperature range (e.g., Dupont Alpha-1) as opposed to a pump with a lower operating temperature range (e.g., SKC). 1.8 EXPLOSIVE ATMOSPHERES Instruments must not be used in atmospheres where the potential for explosion exists (29 CFR 1910.307). Instruments must be intrinsically safe and certified by the • • • • Mine Safety and Health Administration (MSHA) Underwriter’s Laboratory (UL) Factory Mutual (FM) Other testing laboratories recognized by the Occupational Safety and Health Administration (OSHA) When batteries are being replaced, use only the type of battery specified on the safety approval label. Do not assume that an instrument is intrinsically safe. If you are uncertain, verify its safety by contacting the instrument’s manufacturer. 1.9 ATMOSPHERES CONTAINING CARCINOGENS A plastic bag should be used to cover equipment when carcinogens are present. Decontamination procedures for special environments should be followed after using equipment in carcinogenic environments. © 2001 CRC Press LLC
Slide 27: CHAPTER 2 Air Sampling Instrumentation Options This chapter details and discusses the options available for monitoring various contaminants. It includes information for contaminant mixes, thermal enthalpy, interferences, and basis calibration. It also provides cross-section diagrams to illustrate the internal function of various detector and sensor elements. 2.1 VOLATILE ORGANIC COMPOUNDS Sampling for volatile organics essentially means sampling for carbon-containing compounds that can get into the air. The term volatile usually means that the chemical gets into the air through a change of phase from liquid to gas. This phase change occurs when temperatures approach, equal, and exceed the boiling point and continue until equilibrium is established in the environment. For a chemical with a boiling point over 100°F, we would not expect to find that chemical volatilizing at room temperatures. A chemical with a boiling point of 75°F, on the other hand, would be expected to readily volatilize into the environment. Unfortunately, like so many rules, this one is not always true. Volatilization can imply that the chemical is being transported in the airstream by mechanical means that exposes surface area. An example of this anomaly is mercury, which has a boiling point of 674°F. Mercury as a liquid can be dispersed into the airstream as tiny droplets. The phase change occurs around each of these droplets as an equilibrium is established between the mercury liquid and the mercury in the immediate area gas phase. Thus mercury vapor is dispersed into the atmosphere by an equilibrium volatilization phenomenon that is more dependent on mechanical dispersion than on temperature differentials. 2.1.1 Photoionization Detector (PID) Some volatile chemicals can be ionized using light energy. Ionization is based on the creation of electrically charged atoms or molecules and the flow of these positively charged particles toward an electrode. Photoionization (Figure 2.1) is accomplished by applying the energy from an ultraviolet (UV) lamp to a molecule to promote this ionization. A PID is an instrument that measures the total concentration of various organic vapors the in the air. Molecules are given an ionization potential (IP) number based on the energy needed to molecularly rip them apart as ions. Chemicals normally found in the solid and liquid state © 2001 CRC Press LLC
Slide 28: Figure 2.1 Photoionization detector working diagram. (RAE Systems) at room temperatures do not have an IP. By definition IPs are given to chemicals found at room temperature as gases (Figure 2.2). If the IP is higher than the energy that can be transmitted to a molecule by the UV lamp, the molecule will not break apart. Other energy sources can be used from other instruments, such as the flame ionization detector (FID) that has a hydrogen gas flame to impart energy to molecules; of course, these detectors are not called PIDs. The PID is a screening instrument used to measure a wide variety of organic and some inorganic compounds. The PID’s limit of detection for most volatile contaminants is approximately 0.1 ppm. The instrument (Figure 2.3) has a handheld probe. The specificity of the instrument depends on the sensitivity of the detector to the substance being measured, the number of interfering compounds present, and the concentration of the substance being measured relative to any interferences. Newer PIDs have sensitivities down to the parts per billion range. These instruments utilize very high-energy ionization lamps. When toxic effects can occur at the parts per billion range, such as with chemical warfare agents or their dilute cousins—pesticides and other highly hazardous chemicals—these newer PIDs are essential (Figure 2.4). Some PIDs are FM approved to meet the safety requirements of Class 1, Division 2, hazardous locations of the National Electrical Code. © 2001 CRC Press LLC
Slide 29: Figure 2.2 Ionization potentials. (RAE Systems) Figure 2.3 Photoionization detector with a 10.6 eV detector. (RAE Systems) © 2001 CRC Press LLC
Slide 30: Figure 2.4 Handheld VOC monitor with parts per billion detection. (RAE Systems) 2.1.1.1 Calibration An instrument is calibrated by introducing pressurized gas with a known organic vapor concentration from a cylinder into the detector housing. Once the reading has stabilized, the display of the instrument is adjusted to match the known concentration. A calibration of this type is performed each day prior to using the PID (Figure 2.5). If the output differs greatly from the known concentration of the calibration gas, the initial procedure to remedy the problem is a thorough cleaning of the instrument. The cleaning process normally removes foreign materials (i.e., dust, moisture) that affect the calibration of the instrument. If this procedure does not rectify the problem, further troubleshooting is performed until the problem is resolved. If field personnel cannot resolve the problem, the instrument is returned to the manufacturer for repair, and a replacement unit is shipped to the site immediately. The manufacturer’s manual must accompany the instrument. The PID must be kept clean for accurate operation. All connection cords used should not be wound tightly and are inspected visually for integrity before going into the field. A battery check indicator is included on the equipment and is checked prior to going into the Figure 2.5 Calibration gases. (SKC) © 2001 CRC Press LLC
Slide 31: field and prior to use. The batteries are fully charged each night. The PID should be packed securely and handled carefully to minimize the risk of damage. A rapid procedure for calibration involves bringing the probe close to the calibration gas and checking the instrument reading. For precise analyses it is necessary to calibrate the instrument with the specific compound of interest. The calibration gas should be prepared in air. 2.1.1.2 Maintenance Keeping an instrument in top operating shape means charging the battery, cleaning the UV lamp window and light source, and replacing the dust filter. The exterior of the instrument can be wiped clean with a damp cloth and mild detergent if necessary. Keep the cloth away from the sample inlet, however, and do not attempt to clean the instrument while it is connected to an electrical power source. 2.1.2 Infrared Analyzers The infrared analyzer can be used as a screening tool for a number of gases and vapors and is presently recommended by OSHA as a screening method for substances with no feasible sampling and analytical method (Figure 2.6). These analyzers are often factory programmed to measure many gases and are also user programmable to measure other gases. A microprocessor automatically controls the spectrometer, averages the measurement signal, and calculates absorbance values. Analysis results can be displayed either in parts Figure 2.6 An infared gas monitor measures carbon dioxide and sends a signal to the ventilation control system. © 2001 CRC Press LLC
Slide 32: per million or absorbance units (AU). The variable path-length gas cell gives the analyzer the capability of measuring concentration levels from below 1 ppm up to percent levels. Some typical screening applications are as follows: • Carbon monoxide and carbon dioxide, especially useful for indoor air assessments • Anesthetic gases, e.g., nitrous oxide, halothane, enflurane, penthrane, and isoflurane • Ethylene oxide • Fumigants, e.g., ethylene dibromide, chloropicrin, and methyl bromide The infrared analyzer may be only semispecific for sampling some gases and vapors because of interference from other chemicals with similar absorption wavelengths. 2.1.2.1 Calibration The analyzer and any strip-chart recorder should be calibrated before and after each use in accordance with the manufacturer’s instructions. 2.1.2.2 Maintenance No field maintenance of this device should be attempted except for items specifically detailed in the instruction book, such as filter replacement and battery charging. 2.1.3 Remote Collection Various containers may be used to collect gases for later release into laboratory analytical chambers or sorbent beds. The remote collection devices include bags (Figure 2.7), canisters (Figure 2.8), and evacuation chambers. Remote collection refers to the practice of collecting the gas sample, hopefully intact, at a site remote from the laboratory where analysis will occur. This method of sample collection must always take into account the potential of the collecting vehicle reacting with the gaseous component collected during the time between collection and analysis. For this reason various plastic formulations and stainless steel compartments have been devised to minimize reactions with the collected gases. When bags are used, the fittings for the bags to the pumps must be relatively inert and are usually stainless steel (Figure 2.9). Multiple bags may be collected and then applied to a gas chromatograph (GC) column using multiple bag injector systems (Figure 2.10). One innovation in remote sampling of this type is the MiniCan. This device can be preset to draw in a known volume of gas. The MiniCan is then worn by a worker or placed in a static location. Sample collection then occurs without the use of an additional airsampling pump (Figure 2.11). 2.1.4 Oxygen/Combustible Gas Indicators (O2/CGIs)/Toxin Sensors To measure the lower explosive limit (LEL) of various gases and vapors, these instruments use a platinum element or wire as an oxidizing catalyst. The platinum element is one leg of a Wheatstone bridge circuit. These meters measure gas concentration as a percentage of the LEL of the calibrated gas (Figure 2.12). © 2001 CRC Press LLC
Slide 33: Figure 2.7 Gas sample bags are a convenient means of collecting gas and vapor samples in air. (SKC) Figure 2.8 Six-liter canisters can be used for the passive collection of ambient VOCs from 0.1 to 100 ppb over a period of time. (SKC) The oxygen meter displays the concentration of oxygen in percent by volume measured with a galvanic cell. Some O2/CGIs also contain sensors to monitor toxic gases/ vapors. These sensors are also electrochemical (as is the oxygen sensor). Thus, whenever the sensors are exposed to the target toxins, the sensors are activated. Other electrochemical sensors are available to measure carbon monoxide (CO), hydrogen sulfide (H2S), and other toxic gases. The addition of two toxin sensors, one for H2S and one for CO, is often used to provide information about the two most likely contaminants of concern, especially within confined spaces. Since H2S and CO are heavier than © 2001 CRC Press LLC
Slide 34: Figure 2.9 Air sampling pump connected to a Tedlar Bag. (SKC) ambient air (i.e., the vapor pressure of H2S is greater than one), the monitor or the monitor’s probe must be lowered toward the lower surface of the space/area being monitored. Other toxic sensors are available; all are electrochemical. Examples are sensors for ammonia, carbon dioxide, and hydrogen cyanide. These sensors may be installed for special needs. 2.1.4.1 Remote Probes and Diffusion Grids With a remote probe, air sampling can be accomplished without lowering the entire instrument into the atmosphere. Thus, both the instrument and the person doing the sampling are protected. The remote probe has an airline (up to 50 ft) that draws sampled air toward the sensors with the assistance of a powered piggyback pump. Without this arrangement the O2/CGI monitor relies on a diffusion grid (passive sampling). All O2/CGIs must be positioned so that either the diffusion grids over the sensors or the inlet port for the pumps are not obstructed. For instance, do not place the O2/CGI on your belt with the diffusion grids facing toward your body. © 2001 CRC Press LLC
Slide 35: Figure 2.10 The Tedlar Bag Autosampler automates the introduction of up to 21 samples into a GC for quantitative analysis. (Entech Instruments Inc.) Figure 2.11 Stainless steel canisters are used for collecting air samples of VOCs and sulfur compounds over a wide concentration range (1 ppb to 10,000 ppm). This 400-cc unit can be placed at a sampling site for area sampling or attached onto a worker’s belt for personal sampling. (SKC-MiniCans) 2.1.4.2 Calibration Alert and Documentation A calibration alert is available with most O2/CGIs to ensure that the instruments cannot be used when factory calibration is needed. Fresh air calibration and sensor exposure gas calibration for LEL levels and toxins can be done in the field. However, at approximately © 2001 CRC Press LLC
Slide 36: Figure 2.12 Multigas meters are available to allow the user to select as many as five sensors that can be used at one time. (MSA—Passport FiveStar Alarm) 6–12 month intervals, and whenever sensors are changed, factory calibration is required to ensure that electrical signaling is accurate. Always calibrate and keep calibration logs as recommended by the manufacturer. In lieu of the manufacturer’s recommendations, O2/CGIs must be calibrated at least every 30 days. If O2/CGIs are transported to higher elevations (i.e., from Omaha to Denver) or if they are shipped in an unpressurized baggage compartment, recalibration may be necessary. Refer to the manufacturer’s recommendations in these cases. 2.1.4.3 Alarms Alarms must be visible and audible, with no opportunity to override the alarm command sequence once initiated and while still in the contaminated alarm-initiating environment. The alarm can be enhanced up to 150 dBA. The alarm must be wired so that the alarm signal cannot be overridden by calibration in a contaminated environment and thus cease to provide valid information. An audible alarm that warns of low oxygen levels or malfunction or an automatic shutdown feature is very important because without adequate oxygen, the CGI will not work correctly. 2.1.4.4 Recommendations for O2/CGIs At a minimum, all O2/CGIs must contain sensors for detecting levels of oxygen and the LEL percentage of the vapors/gases in the area. In an oxygen-depleted or oxygen-enriched environment, the LEL sensor will burn differently (slower in an oxygen-depleted environment and faster in an oxygen-enriched environment). Thus, in an oxygen-depleted environment the LEL sensor will be slower to reach the burn rate the monitor associates with 10% of the LEL of the calibration gas and vice versa. Consequently, all O2/CGIs must monitor and alarm first on the basis of the oxygen level, then in response to LEL or toxin levels. • The oxygen monitor must be set to alarm at less than 19.5% oxygen (oxygendepleted atmosphere, hazard of asphyxiation) and greater than 22% oxygen (oxygen-enriched atmosphere, hazard of explosion/flame). Note: The confined space regulation for industry (29 CFR 1910.146) defines an oxygen-enriched atmosphere at greater than 23.5% oxygen. • The LEL must be set to alarm at 10% in confined space entries. This alarm should be both audible and visible. The alarm should not reset automatically. In other words, a separate action on the part of the user should be required to reset the alarm. © 2001 CRC Press LLC
Slide 37: The oxygen sensor is an electrochemical sensor that will degrade as the sensor is exposed to oxygen. Thus, whether the sensor is used or not, the oxygen sensor will degrade in a period of 6 to 12 months. Some manufacturers recommend storing the monitor in a bag placed in a refrigerated compartment. This procedure has minimal value. Because the oxygen sensor is constantly exposed to oxygen and will degrade (regardless of usage), O2/CGIs should be used often and continuously—“there is no saving them!’’ In other words, once the O2/CGI is turned on, leave the O2/CGI on. Do not turn the monitor “on and off.’’ 2.1.4.5 Relative Response When using O2/CGIs to monitor the LEL, remember that calibration to a known standard is necessary; all responses to any other gases/vapors will be relative to this calibration standard. Thus, if the O2/CGI is calibrated to pentane (five-carbon chain), the response to methane (one-carbon chain) will be faster. In other words, less of the methane will be necessary in order for the monitor to show 10% of the LEL than if the sensor was exposed to pentane. The LEL sensor is a platinum wire/filament located on one side of a Wheatstone bridge electrical circuit. As the wire is exposed to gases/vapors, the burn rate of the filament is altered. Thus, the resistance of the filament side of the Wheatstone bridge is changed. The O2/CGI measures this change in resistance. • The LEL sensor functions only when the O2/CGI is in use; therefore, some manufacturers will state that usage of the O2/CGI accelerates the breakdown of this sensor. However, because the oxygen sensor is much more susceptible to degradation regardless of usage, turning the monitors on and off just to preserve the LEL sensor is not recommended. • Remember that the LEL readout is a percentage of the LEL listed for each chemical. Thus, if the LEL for a particular calibration gas is 2%, at 10% of the LEL, 0.2% of the calibration gas is present. This comparison is not possible for other than the calibrated gas/vapor atmospheres. As an example, when an O2/CGI is calibrated to pentane and then taken into an unknown atmosphere, then at 10% of the LEL, the sensor’s burn rate is the same as if the sensor had been exposed to 10% of the LEL for pentane. If atmospheres of methane or acetylene are known to be present, the O2/CGI must be calibrated for these gases. 2.1.4.6 Relative Response and Toxic Atmosphere Data No direct correlation can be made under field conditions between the LEL monitor and the level of toxins. Thus, 10% (1 10 2) LEL readings cannot be converted to parts per million (ppm, 1 10 6) by simply multiplying by 10,000. In a controlled laboratory atmosphere using only the atmosphere to which the CGIs were calibrated, and then using many trials of differing atmospheres, relative monitoring responses and correlation to toxin levels may be obtained. However, in the field, and particularly in relatively unknown constituent atmospheres, such correlations cannot be made. © 2001 CRC Press LLC
Slide 38: 2.1.4.7 Special Considerations • Silicone compound vapors, leaded gasoline, and sulfur compounds will cause desensitization of the combustible sensor and produce erroneous (low) readings. • High relative humidity (90–100%) causes hydroxylation, which reduces sensitivity and causes erratic behavior, including inability to calibrate. • Oxygen deficiency or enrichment such as in steam or inert atmospheres will cause erroneous readings for combustible gases. • In drying ovens or unusually hot locations, solvent vapors with high boiling points may condense in the sampling lines and produce erroneous (low) readings. • High concentrations of chlorinated hydrocarbons such as trichloroethylene or acid gases such as sulfur dioxide will depress the meter reading in the presence of a high concentration of combustible gas. • High-molecular-weight alcohols can burn out the meter’s filaments. • If the flash point is greater than the ambient temperature, an erroneous (low) concentration is indicated. If the closed vessel is then heated by welding or cutting, the vapors will increase, and the atmosphere may become explosive. • For gases and vapors other than those for which a device was calibrated, users should consult the manufacturer’s instructions and correction curves. 2.1.4.8 Calibration Before using the monitor each day, calibrate the instrument to a known concentration of combustible gas (usually methane) equivalent to 25–50% LEL full-scale concentration. The monitor must be calibrated to the altitude at which it is used. Changes in total atmospheric pressure due to changes in altitude will influence the instrument’s measurement of the air’s oxygen content. The instrument must measure both the level of oxygen in the atmosphere and the level a combustible gas reaches before igniting; consequently, the calibration of the instrument is a two-step process. 1. The oxygen portion of the instrument is calibrated by placing the meter in normal atmospheric air and determining that the oxygen meter reads exactly 20.8% oxygen. This calibration should be done once per day when the instrument is in use. 2. The CGI is calibrated to pentane to indicate directly the percentage LEL of pentane in air. The CGI detector is also calibrated daily when used during sampling events and whenever the detector filament is replaced. The calibration kit included with the CGI contains a calibration gas cylinder, a flow control, and an adapter hose. The unit’s instruction manual provides additional details on sensor calibration. 2.1.4.9 Maintenance The instrument requires no short-term maintenance other than regular calibration and battery recharging. Use a soft cloth to wipe dirt, oil, moisture, or foreign material from the instrument. Check the bridge sensors periodically, at least every 6 months, for proper functioning. © 2001 CRC Press LLC
Slide 39: 2.1.5 Oxygen Meters Oxygen-measuring devices can include coulometric and fluorescence measurement, paramagnetic analysis, and polarographic methods. 2.1.6 Solid Sorbent Tubes Organic vapors and gases may be collected on activated charcoal, silica gel, or other adsorption tubes using low-flow pumps. Tubes may be furnished with either caps or flame-sealed glass ends. If using the capped version, simply uncap during the sampling period and recap at the end of the sampling period. Multiple tubes can be collected using one pump. Flow regulation for each tube is accomplished using critical orifices and valved regulation of airflow. Calibration of parallel or y-connected multiple tube drawing stations must be done individually for each tube, even in cases where the pump is drawing air through more than one tube in a parallel series (Figure 2.13). In instances where tubes are connected in series, only one calibration draw is done through the conjoined tubes that empty air, one directly into the other (Figure 2.14). Sorbent tubes may be used just to collect gases and vapors or to both collect and react with the collected chemicals. Some of the reactions may produce chemicals that when offgassed could harm the pumps being used to pull air through the sorbent media bed. In these cases either filters or intermediate traps must be used to protect the pumps (Figure 2.15). The following protocols should be followed: • Immediately before sampling, break off the ends of the flame-sealed tube to provide an opening approximately half the internal diameter of the tube. Take care when breaking these tubes—shattering may occur. A tube-breaking device that shields the sampler should be used. • Wear eye protection. • Use tube holders, if available, to minimize the hazards of broken glass (Figure 2.16). • Do not use the charging inlet or the exhaust outlet of the pump to break the ends of the tubes. • Use the smaller section of the tube as a backup and position it near the sampling pump. • The tube should be held or attached in an approximately vertical position with the inlet either up or down during sampling (Figure 2.17). • Draw the air to be sampled directly into the inlet of the tube. This air is not to be passed through any hose or tubing before entering the tube. A short length of protective tape, a tube holder, or a short length of tubing should be placed on the cut tube end to protect the worker from the jagged glass edges. • Cap the tube with the supplied plastic caps immediately after sampling and seal as soon as possible. • Do not ship the tubes with bulk material. For organic vapors and gases, low-flow pumps are required. With sorbent tubes, flow rates may have to be lowered or smaller air volumes (half the maximum) used when there is high humidity (above 90%) in the sampling area or when relatively high concentrations of other organic vapors are present. © 2001 CRC Press LLC
Slide 40: SKC SKC SKC SKC SKC SKC AIRCHEK SAMPLER SAMPLE PERIOD MINUTES START HOLD FLOW AND BATTERY CHECK ¤ INTRINSICALLY SAFE PORTABLE AIR SAMPLING PUMP FOR USE IN HAZARDOUS LOCA TIONS CLASS I, GROUPS A B C D AND CLASS II, GROUPS E F G AND CLASS III, TEMPERATURE CODE T3C. UL LISTED 124U 5 4 3 2 1 SET-UP MODE AIRCHEK SAMPLER MODEL 224-PCXR8 WARNING - SUBSTITUTION OF COMPONENTS MAY IMPAIR INTRIN SIC SAFETY. USE ONLY UL LISTED PORTABLE AIR SAMPLING PUMP BATTERY PACK MODEL P21661 DIGIT SELECT TOTAL ELAPSED TIME DIGIT SET PUMP RUN TIME ON FLOW SERIAL NO. SKC INC. EIGHTY FOUR PA 15330 ADJ Figure 2.13 Multitube sampling allows sampling of multiple contaminants requiring different sampling tubes with one pump. Multitube sampling also allows you to collect timeweighted averages (TWAs) and short-term exposure limits (STELs) side by side. (SKC) 2.1.6.1 Calibration Procedures Set up the calibration apparatus as shown in Figure 2.18, replacing the cassette and cyclone with the solid sorbent tube to be used in the sampling (e.g., charcoal, silica gel, other sorbent media). If a sampling protocol requires the use of two sorbent tubes, the calibration train must include these two tubes. The airflow must be in the direction of the arrow on the tube (Figure 2.19). Sorbent tubes may be difficult to calibrate, especially if flow-restrictive devices must be used (Figure 2.20). © 2001 CRC Press LLC
Slide 41: Figure 2.14 Pump with detector tube sampling train with calibrator. (SKC—pump, low-flow holder, trap tube holder, and electronic calibrator) Figure 2.15 Pump with detector tube sampling train in place. Chemicals may be generated that, if allowed to enter the sampler, could damage the sampler. Therefore, a trap tube must be used between the detector tube and the sampler. (SKC—pump, low-flow holder, and trap tube holder) © 2001 CRC Press LLC
Slide 42: Figure 2.16 Worker wearing sampling pump with sampling train in place in breathing zone. (SKC— 210 Series Pocket Pump®, low flow tube holder) 2.1.7 Vapor Badges Passive-diffusion sorbent badges are useful for screening and monitoring certain chemical exposures, especially vapors and gases (Figure 2.21). Badges are available from the laboratory to detect mercury, nitrous oxide, ethylene oxide, and formaldehyde (Figure 2.22). Interfering substances should be noted. A variation on the vapor badge is available as a dermal patch (Figure 2.23). These dermal patches can also be used in the detection of semivolatiles. 2.1.8 Detector Tubes Detector tubes use the same medium base—silica gel or activated charcoal—as do many sorbent tubes. The difference is that the detector tubes change color in accordance with the amount of chemical reaction occurring within the medium base. The medium base has been treated with a chemical that effects a given color change when certain chemicals are introduced into the tube and reside for a time in the medium. The residence time for the reaction to occur and the volume of air that must be drawn through the detector tubes varies with the chemical and anticipated concentration. All detector tube manufacturers supply the recipe for using their detector tubes as an insert sheet with the tubes. © 2001 CRC Press LLC
Slide 43: Figure 2.17 Sorbent tube placement with protective tube holder. (SKC) Detector tube pumps are portable equipment that, when used with a variety of commercially available detector tubes, are capable of measuring the concentrations of a wide variety of compounds in industrial atmospheres. Each pump should be leak-tested before use. Calibrate the detector tube pump for proper volume at least quarterly or after 100 tubes. Operation consists of using the pump to draw a known volume of air through a detector tube designed to measure the concentration of the substance of interest. The concentration is then determined by a colorimetric change of an indicator that is present in the tube contents (Figure 2.24). Most detector tubes can be obtained locally. Draeger or Sensidyne tubes are specified by some employers; their concentration detection ranges match employers’ needs. Detector tubes and pumps are screening instruments that may be used to measure more than 200 organic and inorganic gases and vapors or for leak detection. Some aerosols can also be measured. Detector tubes of a given brand should be used only with a pump of the same brand. The tubes are calibrated specifically for the same brand of pump and may give erroneous results if used with a pump of another brand. © 2001 CRC Press LLC
Slide 44: Figure 2.18 Cassette and cyclone use. A limitation of many detector tubes is the lack of specificity. Many indicators are not highly selective and can cross-react with other compounds. Manufacturers’ manuals describe the effects of interfering contaminants. © 2001 CRC Press LLC
Slide 45: Figure 2.19 Tube sampling train connected to a sample pump and a flowmeter. (SKC—PCXR8 Sampler and Film Flowmeter) Figure 2.20 Electronic flowmeter connected to sorbent tube sampling train. (SKC—Model 709 Flowmeter) Another important consideration is sampling time. Detector tubes give only an instantaneous interpretation of environmental hazards, which may be beneficial in potentially dangerous situations or when ceiling exposure determinations are sufficient. When longterm assessment of occupational environments is necessary, short-term detector-tube measurements may not reflect TWA levels of the hazardous substances present. Detector tubes normally have a shelf life at 25°C of 1 to 2 years. Refrigeration during storage lengthens the shelf life. Outdated detector tubes (i.e., beyond the printed expiration date) should never be used. © 2001 CRC Press LLC
Slide 46: Figure 2.21 Cross-sectional view of a passive sampler. A diffusion barrier maintains sample uptake by molecular diffusion independent of wind velocity. (SKC—575 Series Passive Sampler) Figure 2.22 Passive badge sampler. (SKC—Formaldehyde Passive Sampler) Figure 2.23 Dermal polyurethane foam (PUF) patches for chlorinated or organonitrogen herbicides. The dermal patches are clipped onto a worker’s clothing or taped to the skin in various locations where absorption may occur. After sampling, the patches are transferred to glass jars, desorbed with isopropanol, and analyzed by gas chromatography/electron capture detection (GC/ECD). (SKC) © 2001 CRC Press LLC
Slide 47: Figure 2.24 Sorbent tube of detector tube. Flow is toward the air sampling pump in the direction of the arrow. 2.1.8.1 Performance Data Specific models of detector tubes can be obtained from the manufacturer (e.g., Draeger, Sensidyne). The specific tubes listed are designed to cover a concentration range that is near the permissible exposure limit (PEL). Concentration ranges are tube dependent and can be anywhere from one hundredth to several thousand parts per million. The limits of detection depend on the particular detector tube. Accuracy ranges vary with each detector tube. The pump may be handheld during operation (weight about 8–11 oz), or it may be an automatic type (weight about 4 lb) that collects a sample using a preset number of pump strokes. A full pump stroke for either type of short-term pump has a volume of about 100 ml. In most cases where only one pump stroke is required, sampling time is about 1 min. Determinations for when more pump strokes are required take proportionately longer. Multiple tubes can be used with newer microcapillary detector tube instruments. Computer chips are programmed to draw preselected air volumes across these detector tubes. Readout is measured based on changes in light absorption across the microcapillary tubes. 2.1.8.2 Leakage Test Each day prior to use, perform a pump leakage test by inserting an unopened detector tube into the pump and attempt to draw in 100 ml of air. After a few minutes check for pump leakage by examining pump compression for bellows-type pumps or return to resting position for piston-type pumps. Automatic pumps should be tested according to the manufacturer’s instructions. In the event of leakage that cannot be repaired in the field, send the pump to the manufacturer for repair. Record that the leakage test was made on a direct-reading data form in the field logbook. 2.1.8.3 Calibration Test Calibrate the detector tube pump for proper volume measurement at least quarterly. Simply connect the pump directly to the bubble meter with a detector tube in-line. Use a detector tube and pump from the same manufacturer. Wet the inside of the 100-ml bubble meter with soap solution. When performing volume calibration, experiment to get the soap bubble even with the 0 ml mark of the burette. For piston-type pumps pull the pump handle all the way out (full pump stroke). Note where the soap bubble stops. For bellows-type pumps compress the bellows fully. For automatic pumps program the pump to take a full pump stroke. For either type pump, the bubble should stop between the 95-ml and 105-ml marks. Allow 4 min for the pump to draw the full amount of air. (This time interval varies with the type of detector tube being used in-line with the calibration setup.) © 2001 CRC Press LLC
Slide 48: Also check the volume for 50 ml (one half pump stroke) and 25 ml (one quarter pump stroke) if pertinent. • A variance of 5% error is permissible. • If the error is greater than 5%, send the pump for repair and recalibration. Record the calibration information required on the calibration log. It may be necessary to clean or replace the rubber bung or tube holder if a large number of tubes have been taken with any pump. 2.1.8.4 Special Considerations Detector tubes should be refrigerated when not in use to prolong shelf life. Detector tubes should not be used when they are cold. They should be kept at room temperature or in a shirt pocket for 1 h prior to use. Lubrication of the piston pump may be required if volume error is greater than 5%. Draeger, Model 31 (Bellows) When checking the pump for leaks with an unopened tube, the bellows should not be completely expanded after 10 min. Draeger, Quantimeter 1000, Model 1 (Automatic) A battery pack is an integral part of this pump. • The pack must be charged prior to initial use. • One charge is good for 1000 pump strokes. • During heavy use, it should be recharged daily. If a “U’’ (undervoltage) message is continuously displayed in the readout window of this pump, the battery pack should be immediately recharged. Matheson-Kitagawa, Model 8014-400a (Piston) When checking the pump for leaks with an unopened tube, the pump handle should be pulled back to the 100-ml mark and locked. • After 2 min, the handle should be released carefully. • The handle should return to a point 6 mm from zero or resting position. After taking 100–200 samples, the pump should be cleaned and relubricated. This procedure involves removing the piston from the cylinder, removing the inlet and pressurerelief valve from the front end of the pump, cleaning, and relubricating. Mine Safety Appliances, Samplair Pump, Model A, Part No. 46399 (Piston) The pump contains a flow-rate control orifice protected by a plastic filter that periodically needs to be cleaned or replaced. To check the flow rate, the pump is connected to a burette, and the piston is withdrawn to the 100-ml position with no tube in the tube holder. © 2001 CRC Press LLC
Slide 49: • After 24–26 s, 80 ml of air should be admitted to the pump. • Every 6 months the piston should be relubricated with the oil provided. Mine Safety Appliances Kwik-Draw Sampling Pump, Part No. 487500 (Bellows) The pump contains a filter disk that needs periodic cleaning or replacement. The bellows shaft can be cleaned and lubricated with automotive wax if operation becomes jerky. Sensidyne-Gastec, Model 800, Part No. 7010657-1 (Piston) This pump can be checked for leaks as mentioned for the Kitagawa pump; however, the handle should be released after 1 min. Periodic relubrication of the pump head, the piston gasket, and the piston check valve is needed and is use dependent. A variation on the detector tube technology is the use of sorbent packed tubes that change color in response to ambient airflow. The application of reactive adsorbing and/or absorbing chemicals onto test strips is also used to provide a general indication of airborne contaminant levels. An example is the ozone test strip used to monitor both outdoor and indoor ozone levels (Figure 2.25). 2.1.9 Formaldehyde Formaldehyde sampling can be accomplished by both passive and active (use of a pump) techniques. • When long duration sampling is required in indoor air investigations, passivesampling may be the method of choice (Figure 2.26). • Vapor badges can be used to monitor personnel exposures. Figure 2.25 Ozone strips provide quick indication of ambient levels of ozone in both indoor and outdoor air. Ozone strips are chemically treated to react with ozone. Test strips are placed in the area to be tested. After 10 min, compare the test strip with the color scale on the test strip package. Results display in four distinct colors from light yellow to brown. Each represents a certain level of ozone concentration. (SKC) © 2001 CRC Press LLC
Slide 50: Figure 2.26 A formaldehyde passive air sampler for indoor air sampling. Easy to use, it is designed for long-term measurement (5 to 7 days). Its detection limit is 0.01 ppm. (SKC) Neither of these methods is recommended for acute exposure scenarios because the sampling medium will quickly become overloaded. In acute exposure scenarios sampling with a sorbent tube attached to an air sampling pump, or a detector tube attached to a pump/bellows, is recommended. Attachment implies that the pump will be used to draw a known volume of air quickly into the media. This air will be at a concentration anticipated to provide information, but below that which would overload the media. 2.2 OZONE METER The ozone meter detector uses a thin-film semiconductor sensor. A thin-film platinum heater is formed on one side of an alumina substrate. A thin-film platinum electrode is formed on the other side, and a thin-film semiconductor is formed over the platinum electrode by vapor deposition. The semiconductor film, when kept at a high temperature by the heater, will vary in resistance due to the absorption and decomposition of ozone. The change in resistance is converted to a change of voltage by the constant-current circuit. The measuring range of the instrument is 0.01–9.5 ppm ozone in air. The readings are displayed on a liquid crystal display that reads ozone concentrations directly. The temperature range is 0– 40°C, and the relative humidity (RH) range is 10–80%. The instrument is not intrinsically safe. • The instrument must not be exposed to water, rain, high humidity, high temperature, or extreme temperature fluctuation. • The instrument must not be used or stored in an atmosphere containing silicon compounds, or the sensor will be poisoned. • The instrument is not to be used for detecting gases other than ozone. Measurements must not be performed when the presence of organic solvents, reducing gases (such as nitrogen monoxide, etc.), or smoke is suspected; readings may be low. 2.2.1 Calibration Calibrate the instrument before and after each use. Be sure to use a well-ventilated area; ozone levels may exceed the PEL for short periods. Calibration requires a source of ozone. Controlled ozone concentrations are difficult to generate in the field, and this calibration is normally performed at the laboratory. Gas that is either specially desiccated or humidified must not be used for preparing calibration standards, as readings will be inaccurate. © 2001 CRC Press LLC
Slide 51: 2.2.2 Maintenance The intake-filter unit-Teflon sampling tube should be clean, connected firmly, and checked before each operation. Check pump aspiration and sensitivity before each operation. 2.3 TOXIC GAS METERS Toxic gas meters use an electrochemical voltametric sensor or polarographic cell to provide continuous analyses and electronic recording. Sample gas is drawn through the sensor and absorbed on an electrocatalytic-sensing electrode, after passing through a diffusion medium. An electrochemical reaction generates an electric current directly proportional to the gas concentration. The sample concentration is displayed directly in parts per million. The method of analysis is not absolute; therefore, prior calibration against a known standard is required. Exhaustive tests have shown the method to be linear; thus calibration at a single concentration is sufficient. Sensors are available for sulfur dioxide, hydrogen cyanide, hydrogen chloride, hydrazine, carbon monoxide, hydrogen sulfide, nitrogen oxides, chlorine, ethylene oxide, and formaldehyde. These sensors can be combined with O2/CGIs in one instrument (Figure 2.27). Interference from other gases may be a problem. The sensor manufacturer’s literature must be consulted when mixtures of gases are tested. 2.3.1 Calibration Calibrate the direct-reading gas monitor before and after each use in accordance with the manufacturer’s instructions and with the appropriate calibration gas. • When calibrating under external pressure, the pump must be disconnected from the sensor to avoid sensor damage. If the span gas is directly fed into the instrument from a regulated pressurized cylinder, the flow rate should be set to match the normal sampling rate. Figure 2.27 MSA Passport. © 2001 CRC Press LLC
Slide 52: • Due to the high reaction rate of the gas in the sensor, substantially lower flow rates result in lower readings. This high reaction rate makes rapid fall time possible—simply by shutting off the pump. Calibration from a sample bag connected to the instrument is the preferred method. 2.4 SEMIVOLATILE ORGANIC COMPOUNDS (SVOCs) Semivolatiles like polycyclic biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), dioxins, furans, and pesticides present unique sampling challenges. The term semivolatile is used for chemicals that do not normally volatilize into the gaseous state at room temperature (75°F; Figure 2.28). These chemicals can enter the airstream through a variety of mechanisms, the most prevalent being dispersed as adsorbed or absorbed particulate contaminants. Heating phenomena such as smoking, direct heating of semivolatiles, and chemical usage in which semivolatiles must be applied in a heated state (asphalting) may also change the semivolatiles into volatiles. Often very high collection rates (10–30 l/min) must be used to pick up semivolatile contaminants from the airstream (Figure 2.29). Certain EPA methods and stack sampling requirements also call for the use of very high flow rates. In these instances special pumps must be used. 2.4.1 PAHs PAHs have Koc values that are characteristic of chemicals that tend to readily adsorb to the soil particulate or to any other particulate present. PAHs are expected to bind strongly to soil and to not leach extensively to groundwater through volatilization. Photolysis and hydrolysis do not appear to be significant PAH breakdown processes in soil. However, while little volatilization will occur from the soil, leaching to groundwater is possible. PAHs released to the water will dissolve at ambient pH. The dissociated form will degrade (hours to days). Figure 2.28 High volume PUF tube for pesticides and PAHs. (SKC) © 2001 CRC Press LLC
Slide 53: Figure 2.29 Dual-diaphragm pump for indoor and outdoor collection of particulates, PAHs, and other compounds requiring flows from 10 to 30 l/min. High-flow pumps are used for asbestos, PAHs in indoor air, PM10 and PM2.5 in indoor air, bioaerosol sampling, stack sampling, fenceline monitoring, and background monitoring. (SKC—AirCheck HV30 Environmental Air Sampler) Photolysis is expected to occur near the water surface, and biodegradation in the water column is expected. Biodegradation probably becomes significant after acclimation (may take several weeks). PAHs with four or fewer aromatic rings are degraded by microbes. Transport of PAH biodegradation products to groundwater has been documented in some cases. The mechanism for particulate dispersion first requires that the semivolatile chemical bind to a particulate. When that particulate is dispersed into the air, the semivolatile chemical is also dispersed. So the methods used for particulate sampling are also applicable for semivolatile sampling. The toxicological problems with the semivolatile chemical on particulate dispersion come into play as the particulate is inhaled, and off-gassing occurs in the body of the semivolatile chemical. The following decision logic is an example of the evaluation of semivolatile exposure potential, in this case PAHs, at outdoor sites: • Usually 5 mg/m3 is assumed to be the airborne particulate concentration necessary to have visible dust. Therefore, if during sampling activities, dust is apparent, semivolatile exposure should be of concern if the semivolatile exposure limits are less than the visible dust limits. © 2001 CRC Press LLC
Slide 54: —PAH dust exposure PEL levels are below 5 mg/m3; consequently, air monitoring would need to be conducted on any site where PAHs are expected and visible dusts are generated. —This air monitoring should be downwind from activities judged invasive of soil layers and potentially subject to dust cloud generation. • Monitoring for PAH levels is conducted using a personal air-sampling pump. The exposure target limit is usually set at 0.2 mg/m3 because that is the limit for Benzo(a)pyre. The setting of target limits for semivolatiles is usually based on the most toxic of the expected cogenitors. Cogenitors are essentially the different molecular conformations that a semivolatile chemical can take. • Complete suspension of these contaminants within an airstream on-site is not physically probable, and misting of the sampling area should continually remove particulates from the air; therefore, high efficiency particulate air (HEPA) cartridge air-purifying respirators should be sufficient to protect samplers. • Because PAH contamination is often associated with the presence of petroleum contamination, VOC levels should be continually monitored using a PID. If the PID records a sustained deflection of 1 ppm, workers should evacuate the exclusion zone. The presence of volatile organics revealed by sustained PID readings will require further site evaluation for PAH potential exposure. —Further evaluation for potential exposures to PAHs will require soil sampling, with attendant air dispersion calculations and air monitoring for particulates. —Unfortunately, we do not have real-time instrumentation to monitor for PAHs. PAH sampling requires that laboratory analyticals or on-site immunoassay testing must be accomplished. Therefore, until results are obtained and interpreted, on-site personnel would be required to wear HEPA-OV cartridge fullface air-purifying respirators. The on-site monitoring sequence is as follows: • Visible dust: 2 l/min personal air-sampling pumps will be used to draw air through filter cassettes. Cassettes will be packaged and sent to the contract laboratory for analysis. • Ongoing site work will continue with dust suppression engineering controls. Personnel will don HEPA cartridge air-purifying respirators. • If organic vapors are also present, HEPA-OV combination cartridges should be donned. The above example illustrates the need for careful evaluation of the potential for exposure during sampling. Monitoring decisions when semivolatiles are present must always be made by personnel who understand that these chemicals cannot be detected by the sense of smell or predicted by visible dust. 2.4.2 PCBs and Creosote PCBs are expected in electrical transformers, fluorescent light fixture ballasts, and possibly on some building materials where oils have leaked or the transformers have exploded. Generally, all transformers and suspect containers are inspected to determine the contents of the liquids present. Site inspections include a review of transformer labels © 2001 CRC Press LLC
Slide 55: or other identifying signage. This review is conducted in the field by comparing the reviewed information against known PCB-containing placards or by conducting a phone conversation with the owner of the transformer or the manufacturer. When containers suspected of containing PCBs are found, representative samples may be collected to evaluate the content and concentrations. These samples are evaluated in the field by utilizing Rapid Assay Analysis (RAA) for PCBs or through laboratory analysis. Building materials suspected of being contaminated with PCBs, such as concrete beneath a leaking transformer, may be sampled and analyzed following the same procedures. In the case of stained concrete, a sample would be obtained by drilling the concrete and preparing the dust for analysis. RAA is a method utilizing amino assay techniques for field specific analysis. The amino assay field test kit is prepared in the laboratory for analyzing a specific compound, in this case PCBs or Aroclors. 2.4.3 Pesticides and PAHs—PUF Tubes Both pesticides and PAHs can be collected in PUF tubes. PUF tubes are available for both high-volume and low-volume sampling (Figure 2.30). The sampling volume requirement is determined by the regulatory onus and the chemical constituency of the anticipated sample. Figure 2.30 Low volume PUF tubes for pesticides (for EPA Methods TO-10A and IP-8 and ASTM D4861 and D4947) designed for sampling common pesticides, including organochlorine, organophosphorus, pyrethrin, triazine, carbonate, and urea. (SKC) © 2001 CRC Press LLC
Slide 56: 2.5 ACID GASES OR CAUSTICS Volatile acid gases may be an inappropriate designation. Acid gases are often generated during a reaction, and the latent volatility of the acid gas is really not an issue. Thermal volatilization based on boiling point predictions and mechanical dispersion may be of less importance than the rate of the reaction generating the acid gas or caustic. However, in addition to this reaction phenomenon, acid gases such as chlorine are given off when the liquid solution is distributed around an area. Here we have a classic case of the liquid to gas interface seeking an equilibrium. If air currents sweep the generated gas concentration away from this equilibrium site, the liquid will again yield molecules to the gas phase to again achieve another equilibrium. Acid gases and caustics with their corrosive or caustic properties can have health effects that include both acute toxicological and physical manifestations, such as watering eyes and respiratory tract irritation. Because of these effects, sampling for acid gases and caustics must begin upon approach to the area of concern. Sampling for acid gases and caustics may use all of the techniques specified for any volatile. Some acid gases and caustics are dispersed and adsorbed to particulate; therefore, particulate sampling techniques apply. The reaction phenomenon must always be considered during any sampling of acid gases or caustics. Any real-time instrumentation with unprotected metal sensors, lamp filaments, or sensor housings will often be rendered useless, as the acid gases or caustics interact with the metals through reduction-oxidation (redox) reactions. 2.5.1 Impingers Impingers may be used to bring acid/caustic-laced particulates into solutions that are retained within the impinger’s vessel. Vapors, mists, and gases may also be introduced into the impinger solution. When the reaction within the impinger vessel may cause offgassing, a filter or media barrier (see Figures 2.31, 2.32, and 2.33) may be required between the air sampling pump and the impinger vessel tubing to the pump (Figure 2.34). Midget impingers may be worn as personal sampling devices (Figure 2.35). The main concern with impingers as sampling devices, especially for personnel, is the danger of spills. 2.5.2 Sorbent Tubes Sampling media must also be acid and caustic resistant. Sampling for acids and caustics is often discussed in terms of using silica gel sorbent tubes. The procedure for this sampling is the same as that for volatiles where charcoal tubes are often used. The essential problem with the silica gel tubes is that they tend to plug up! The use of dual flow tubes is some insurance that if one tube plugs up, the other might still remain effective to provide data from the sampling interval. In instances where silica gel tubes continue to plug up, switching to larger bore silica gel tubes or altering the sampling interval (less time) may be needed. If this procedure does not work, switching to charcoal tubes may be the only other solvent tube option. These sampling routines (see Figure 2.36) may be at odds with the recommended National Institute of Occupational Safety and Health (NIOSH) methods that may call for small bore silica gel tubes at low flow rates for extended periods of time. If so, decision logic must be documented, with this documentation linked to the competency of the individual who devised the sampling plan. © 2001 CRC Press LLC
Slide 57: Figure 2.31 In-line traps with replacement sorbent tubes are connected between the pump and impinger holder to protect the pump. (SKC) 2.5.3 Detectors Various detector tubes are available for acid gases and caustics. Chemical-specific detectors are increasingly available as hard-wired permanent detectors based on electrochemical sensors. As with any other electrochemical sensor, recovery of the sensor after overdosing with a chemical may take time or may not be possible at all. © 2001 CRC Press LLC
Slide 58: Figure 2.32 Impinger trap to prevent impinger liquids from being drawn into the sample pump. Solid sorbents may be added to the trap when volatile liquids are used to protect the pump chambers from exposure to vapors. (SKC) 2.5.4 pH Litmus Paper or Meter pH litmus papers or meters are particularly valuable on sites where acid gases and caustics may be of concern. Many sampling events require concurrent bulk sampling, and often the pH of these samples can be effectively characterized in the field. 2.5.4.1 Calibration Calibrations for pH meters generally follow this regime: • Temperature and conductance are factory calibrated. • To recalibrate conductance in the field (if necessary): © 2001 CRC Press LLC
Slide 59: Figure 2.33 Impinger and in-line trap holder mounted on sample pump. Use a trap impinger to prevent impinger liquids from being drawn into the sample pump. Solid sorbents may be added to the trap to protect the pump chamber from exposure to vapors when volatile liquids are used. (SKC) Figure 2.34 Impinger/trap sampling train with flowmeter. (SKC—Universal Sampler with Double Impinger Holder attached to UltraFlo® electronic calibrator) © 2001 CRC Press LLC
Slide 60: Figure 2.35 Teflon PFA (fluoropolymer) impingers. These vessels are completely inert to virtually all chemicals and perform well in both high temperature and cryogenic applications. (SKC) Figure 2.36 Worker wearing sampling pump and two tubes side-by-side for simultaneous tube sampling. (SKC) © 2001 CRC Press LLC
Slide 61: —Remove the black plug revealing the adjustment potentiometer screw. —Add standard solution to a cup, discard, and refill. —Repeat the detection procedure until the digital display indicates the same value twice in a row. —Adjust the potentiometer until the digital display indicates the known value of conductance. —Increase the digital display reading by turning the adjustment potentiometer screw counterclockwise. —Decrease the digital display reading by turning the adjustment potentiometer screw clockwise. To standardize the pH electrode: • Place the pH electrode in the 7.0 buffer bottle. • Adjust the “zero’’ potentiometer on the face of the tester to “7.00.’’ • Place the pH electrode in the 4.0/10.0 buffer bottle (depending on range of concern at your site). • Adjust the “slope’’ potentiometer on the face of the tester to either 4.0 or 10.0. • Repeat the “zero’’ and “slope’’ adjustments several times—to ensure interaction stability. 2.6 MERCURY ANALYZER/GOLD FILM ANALYZER A gold-film analyzer draws a precise volume of air over a gold-film sensor. A microprocessor computes the concentration of mercury in milligrams per cubic meter and displays the results on the digital meter. This meter is selective for mercury and eliminates interference from water vapor, sulfur dioxide, aromatic hydrocarbons, and particulates. In high concentrations of mercury vapor the gold film saturates quickly and should not be used for concentrations expected to be over 1.5 mg/m3. Hydrogen sulfide is an interferant. Lead may also be an interferant. 2.6.1 Jerome Mercury Analyzer A similar instrument is manufactured by Baccarach. The Jerome is discussed here to illustrate the general principles of operation in the detection of mercury vapors. The Jerome 431 Gold Film Sensor is inherently stable and does not require frequent calibration. The interval between calibrations is recommended at every 12 months. The Jerome Mercury Analyzer is factory calibrated using National Bureau of Standards (NBS) traceable permeation tubes. These permeation tubes have been rated at an accuracy of 2%. Calibration includes stability of the calibration gas source being assured, elimination of any pressure differential in the calibration gas stream, and precise control of ambient temperature. Hence, calibration cannot be done in the field. The Jerome Mercury Analyzer, equipped with a Gold Film Sensor, has these qualities: • • • • • Rapid response time ( 4 s) LCD display—direct reading Data logger and software 0.003 mg/m3 Hg sensitivity Accuracy 5% at 0.107 mg/Hg © 2001 CRC Press LLC
Slide 62: 2.6.2 Survey Procedures • Document that the instrument is calibrated. • Obtain and record a background reading. • Survey with the Jerome Mercury Analyzer: —Insert the probe in or near the area to be surveyed. —For surface areas hold the probe 6 in. or closer to the survey point. —For sink traps do not put the probe in water; allow a 10-s residence time of the probe in the headspace of the trap prior to sample readout. • Document readings in the field logbook. • Photograph general locations and specific areas of concern. 2.6.3 Precautions for Area Surveys • Include all suspected rooms, hallways, adjacent administrative space, and storage rooms, including behind and underneath cabinets, refrigerators, sinks, and equipment. • Include all locations where mercury was used or stored. • Include all cracks, crevices, and delaminated surface areas. 2.6.3.1 Calibration Calibration should be performed by the manufacturer or a laboratory with special facilities to generate known concentrations of mercury vapor. Instruments should be returned to the manufacturer or a calibration laboratory on a regular schedule. 2.6.3.2 Maintenance Mercury vapor instruments generally contain rechargeable battery packs, filter medium, pumps, and valves that require periodic maintenance. Except for routine charging of the battery pack, most periodic maintenance will be performed during scheduled calibrations. 2.7 PARTICULATES—SAMPLED BY FILTRATION/IMPACTION (FIGURE 2.37) In sampling for particulates, the particulates must be filtered out or removed from the airstream by impaction. Particulates that are suspended in the airstream come in many sizes; therefore, the first question is whether exposure standards are based on the respirable fraction or the total particulate levels. Multiple-use calibration chambers may be used as protective environments around the various filters, cyclones, and inhalable particulate monitors. These calibration chambers effectively protect the particulate collection devices from extraneous particulate loading during calibration cycles and airstream fluctuations. Total particulates are often analyzed by gravimetric methods. © 2001 CRC Press LLC
Slide 63: Figure 2.37 Exploded view of a 37-mm filter cassette. (SKC) 2.8 GRAVIMETRIC FILTER WEIGHING PROCEDURE The step-by-step procedure for weighing filters depends on the make and model of the balance. Consult the manufacturer’s instruction book for directions. In addition, follow these guidelines: • Smoking and/or eating must not take place in the weighing area—both generate extraneous particulate matter in the airstream. • Handle all filters with tongs or tweezers. Do not handle filters with bare hands. • Desiccate all filters at least 24 hours before weighing and sampling. Change desiccant before the dessicant completely changes color (i.e., before the blue desiccant turns pink). Evacuate the desiccator with a sampling or vacuum pump. • Zero the balance prior to use. • Calibrate the balance prior to use and after every 10 samples. © 2001 CRC Press LLC
Slide 64: • Immediately prior to placement on the balance, pass all filters over an ionization unit to remove static charges. (After 12 months of use, return the unit to the distributor for disposal.) • Weigh all filters at least twice. —If there is more than a 0.005 mg difference in the two weighings, repeat the zero calibration and reweigh. —If there is less than a 0.005 mg difference in the two weighings, average the weights for the final weight. • Note: To avoid damage to the weighing mechanism, take care not to exert downward pressure on the weighing pan(s). • Record all the appropriate weighing information (in ink) in the weighing log. • In reassembling the cassette assembly, remember to add the unweighed backup pad. When weighing the filter after sampling, desiccate first and include any loose material from an overloaded filter and cassette. 2.9 TOTAL DUST AND METAL FUMES A variety of filtration options is available to collect particulates. Sampling options are defined based on the regulatory onus and the sampling environment. Some examples of these options are as follows: • Collect total dust on a preweighed, low-ash polyvinyl chloride (PVC) filter at a flow rate of about 2 l/min, depending on the rate required to prevent overloading. Weigh PVC filters before and after taking the sample. • Collect metal fumes on a 0.8- m mixed cellulose ester filter at approximately 1.5 l/min, not to exceed 2.0 l/min. • When the gravimetric weight needs to be determined for welding fumes, collect these fumes on a low-ash PVC filter. Take care to avoid overloading the filter, as revealed by any loose particulate in the filter cassette housing. Personal sampling pumps must be calibrated before and after each day of sampling, using a bubble meter method (electronic or mechanical) or the precision rotameter method (which has been calibrated against a bubble meter). 2.10 RESPIRABLE DUST Respirable dust is a component of particulates in the airstream that will deposit within the gaseous exchange areas of the lung (Figure 2.38). Respirable particles are just the right size to travel with inspired air into the alveoli of the lung. Once in the alveoli, these particles may be a simple irritant or may dissolve and, thus, become chemicals in suspension with tissue fluids. These suspended chemicals are then available to exert toxic and carcinogenic effects. Respirable dusts that do not go into solution pose another danger. These insoluble dusts/particulates/fibers associated with respirable dusts are easy to breathe in, proceed with ease deeply into the lung, and once in the lung may stay in the tissue bed forever. © 2001 CRC Press LLC
Slide 65: Figure 2.38 Inhalable particulate dust particles have a 50% cut point of 100 g and are hazardous when deposited anywhere in the respiratory tract. Thoracic particulate particles have a 50% cut point of 10 g and are hazardous when deposited anywhere in the lung airways and gas-exchange regions. Respirable particulate dust particles have a 50% cut point of 4 g and are hazardous when deposited anywhere in the gas exchange regions. (SKC) • Inert minerals such as asbestos cause fibrosis formation within the lungs by just mechanically irritating surrounding tissue. • Other not so inert chemicals may produce biochemical effects as the body heats up the formerly semivolatile chemicals adsorbed or absorbed on the respired particulates. PAHs off-gas in the lung and become biochemically available through this body heat phenomenon. For total particulate sampling results the “guess’’ is that 60% of the particles available in the airstream are ultimately respirable. The cut point for these particles is 50% at 4 m. When health effects and exposure limits are based on respirable dusts, • The 60% of total assumption must be made. • Special instrumentation must be used to segregate out only the respirable fraction of total dust (see Figures 2.39, 2.40, and 2.41). 2.10.1 Cyclones Cyclones of various types (aluminum, plastic) are used to collect respirable dust fractions. Plastic cyclones are the only choice in acid-gas contaminated atmospheres (Figures 2.42, 2.43, and 2.44). Collect respirable dust using a clean cyclone equipped (see © 2001 CRC Press LLC
Slide 66: Figure 2.39 Exploded view of a Spiral Sampler. (SKC) Figure 2.45) with a preweighed low-ash PVC filter (Figure 2.46). The flow rate should be 1.5–1.9 l/min. 2.10.1.1 Silica Respirable Dust—Cyclone Collection Collect silica only as a respirable dust. Aluminum cyclones are recommended to ensure that the cyclone material does not interact or become part of the sample (Figures 2.47 and 2.48). Silica at sufficient velocity may etch a plastic cyclone. A bulk sample should also be submitted to provide a basis for comparing silica levels in stock to ultimate respirable levels of dust. All filters used must be pre- and postweighed. Calibration Procedures 1. Calibrate at the pressure and temperature where the sampling is to be conducted. 2. For respirable dust sampling using a cyclone, or for total dust sampling using an open-face filter cassette, set up the calibration apparatus as instructed. 3. Place the open-face filter cassette or cyclone assembly in a 1-l jar. The jar is provided with a special cover (Figure 2.49). If an aluminum cyclone is used, an aluminum cyclone calibration chamber can also be used in lieu of a 1-l sampling chamber (Figure 2.50). 4. Connect the tubing from the electronic bubble meter to the inlet of the jar. 5. Connect the tubing from the outlet of the cyclone holder assembly or from the filter cassette to the outlet of the jar and then to the sampling pump. 6. Calibrate the pump. Readings must be within 5% of each other. The cyclone and filter cassette are now ready to be used. A holder makes placement of this assembly possible both for personnel and area sampling needs (Figure 2.51). 2.10.1.2 Cyclone Cleaning For cyclone cleaning the following is required: • Unscrew the grit pot from the cyclone. • Empty the grit pot by turning it upside down and tapping it gently on a solid surface. • Clean the cyclone thoroughly and gently after each use in warm soapy water or, preferably, wash in an ultrasonic bath. © 2001 CRC Press LLC
Slide 67: Figure 2.40 Calibration curves from Aerosol Dynamics, Inc. of the SKC spiral particle sampler PM2.5 using latex particles at 2.0 l/min. The data show a reasonable fit to the American Conference of Governmental Industrial Hygienists (ACGIH) respirable curve with a 4 m cut point. (SKC) • Rinse thoroughly in clean water, shake off excess water, and set aside to dry before reassembly. • Never insert anything into the cyclone during cleaning. • Inspect the cyclone parts for signs of wear or damage such as scoring, rifling, or a loose coupler. • Replace units or parts if they appear damaged. • Leak test the cyclone at least once a month with regular usage. © 2001 CRC Press LLC
Slide 68: Figure 2.41 Spiral Sampler for respirable dust (a model available for PM2.5). (SKC) Figure 2.42 The GS cyclone is a conductive plastic unit that holds a filter cassette for collecting respirable dust particles. The GS cyclone has a 50% cut point of 4.0 m at 2.75 l/min. (SKC) 2.11 INHALABLE DUSTS (FIGURES 2.52 AND 2.53) Inhalable dusts include all of those dusts from the general airstream that normal humans can bring into their respiratory tracts. The respiratory tract includes everything from the nose to the base of the lungs (Figure 2.54). Inhalable dusts have a 50% cut point of 100 m. Special inhalable dust samplers are used to collect only inhalable dusts; these samplers may vary according to the size of particulates collected (Figures 2.55, 2.56, and 2.57). © 2001 CRC Press LLC
Slide 69: Figure 2.43 GS Cyclone attached to a sampling pump. (SKC) 2.12 PERSONNEL ENVIRONMENTAL MONITORS (PEMs) For particulate segregation at either the 2.5 m or 10 m size, special personnel monitors are available. These PEMs use a single-stage impaction method to select particle size. The name is indicative of both personnel exposure concerns and the Environmental Protection Agency (EPA) particulates of concern given in the Clean Air Act requirements— thus personnel and environmental (Figures 2.58 and 2.59)! © 2001 CRC Press LLC
Slide 70: Figure 2.44 The conductive plastic respirable dust cyclone is a lightweight conductive plastic unit. The unit is designed for a 50% cut point of 5.0 m at 1.9 l/min and 4.0 m at 2.2 l/min. Conductive plastic construction eliminates static problems. (SKC) 2.13 WELDING FUMES When sampling for welding fumes, the filter cassette must be placed inside the welding helmet to obtain an accurate measurement of the employee’s exposure. If, however, the welding helmet cannot be used as a sampling environment, the personal sampling pump cassette can be attached in the breathing zone at collar level. The resulting information can be used as a screening tool: “The air outside the helmet was (not) at a level of concern; therefore, the air inside the welding helmet was (not) at a level of concern.’’ Welding fume samples are normally taken using 37-mm filters and cassettes; however, if these cassettes will not fit inside the helmet, 25-mm filters and cassettes can be used. Care must be taken not to overload the 25-mm cassette when sampling. 2.14 ASBESTOS Collect asbestos on a special 0.8- m pore size, 25-mm diameter mixed cellulose ester filter with a backup pad. © 2001 CRC Press LLC
Slide 71: Figure 2.45 A cyclone attached to air sampling pump. (SKC) Figure 2.46 Exploded view of a respirable dust cyclone. (SKC) © 2001 CRC Press LLC
Slide 72: Figure 2.47 Two aluminum respirable dust cyclone models can be used with a 25- or 37-mm filter loaded onto a three-piece filter cassette. The cyclone separates the dust particles according to size. The respirable dust particles collect on a filter for analysis, while the larger dust particles fall into the grit pot and are discarded. (SKC) • Use a fully conductive cassette with conductive extension cowl. • Sample open face in worker’s breathing zone. • Ensure that the bottom joint (between the extension and the conical black piece) of the cassette is sealed tightly with a shrink band or electrical tape. • Point the open face of the cassette down to minimize contamination. © 2001 CRC Press LLC
Slide 73: Figure 2.48 Exploded view of a respirable dust cyclone cassette assembly. (SKC) Figure 2.49 A calibration chamber allows calibration when using a cyclone, PUF tube, OVS tube, the IOM, or PEM. (SKC—Multipurpose Calibration Chamber) • Use a flow rate of 0.5–5 l/min; 1 l/min is suggested for general sampling. Office environments allow up to 5 l/min. • Calibrate pump before and after sampling. Calibration may be done with the cassette and cyclone replaced by the asbestos filter cassette (Figure 2.60). © 2001 CRC Press LLC
Slide 74: Figure 2.50 Aluminum cyclone calibration chamber. (SKC) Figure 2.51 Cassette holder on aluminum cyclone with filter cassette (37 mm). (SKC) • Do not use nylon or stainless-steel adapters if in-line calibration is done. • Sample for as long a time as possible without overloading (obscuring) the filter. • Instruct the employee to avoid knocking the cassette and to avoid using a compressed-air source that might dislodge the sample while sampling. • Submit 10% blanks, with a minimum in all cases of 2 blanks. Where possible, collect and submit to the laboratory a bulk sample of the contaminant suspected to be in the air. © 2001 CRC Press LLC
Slide 75: Figure 2.52 Inhalable dust sampler. Simulates dust collection of the nose and mouth. Meets NIOSH method 5700 sampling criteria for formaldehyde on dust. (SKC—IOM Inhalable Dust Sampler) IOM Figure 2.53 Exploded view of IOM inhalable dust sampler. (SKC) © 2001 CRC Press LLC MPLER SA
Slide 76: About Dust Exposure An individual’s personal dust exposure does not depend solely on dust in the outside air. People now spend less time outdoors; therefore, indoor sources of dust particles can be just as important. In the future, personal measurement of PM2.5 may become more important than ambient air dust monitoring for PM2.5 for health effects studies. The EPA plans to examine PM2.5 using personal dust sampling devices in microenvironments—inside and outside schools, homes, and workplaces. About Particulates The 4 m convention is based on respirability of all dust particles no matter the source. However, the PM2.5 convention separates dust particles based on likely sources. The most significant contributors to dust particles smaller than 2.5 m include mechanical processes such as rock weathering that causes windblown dust, rock crushing, building demolition, and home remodeling (plaster and wood dust). Figure 2.54 Information provided by SKC. AIRCHEK SAMP LER SAMPLE PERIOD MINUTES FLOW AND BATTERY CHECK START HOLD ¤ INTRINSICALLY SAFE PORTABLE AIR SAMPLING PUMP FOR USE IN HAZARDOUS LOCA TIONS CLASS I, GROUPS ABCD AND CLASS II, GROUPS EFG AND CLASS III, TEMPERATUR CODE T3C. E UL LISTED 124U 5 4 3 SET-UP MODE DIGIT SELECT TOTAL ELAPSED TIME AIRCHEK SAMPLE MODEL 224-PCX R R8 DIGIT SET PUMP RUN TIME ON FLOW 2 1 BATTERY ADJ SERIAL NO. SKC INC. EIGHTY FOUR - SUBSTITUTIO COMPONENTS N OF MAY IMPAIR SIC SAFETY. INTRIN USE ONLY UL LISTED PORTABLE AIR SAMPLING PUMP PACK MODEL P21661 WARNING PA 15330 Figure 2.55 Sampling train using Button inhalable dust sampler. (SKC) © 2001 CRC Press LLC
Slide 77: Figure 2.56 A Button aerosol inhalable dust sampler is a reusable filter sampler with a porous curved-surface sampling inlet designed to improve the collection characteristics of inhalable dust particles ( 100 m in aerodynamic diameter). (SKC) Figure 2.57 Exploded view of the Button aerosol inhalable dust sampler. (SKC) © 2001 CRC Press LLC
Slide 78: Figure 2.58 The PEM is a lightweight, personal sampling device consisting of a single-stage impactor and a final filter. Aerosol particulates are sampled through the single-stage impactor to remove particulates above the 2.5 or 10 m cut point, depending on which sampling head is chosen. (SKC) 2.15 DIRECT-READING DUST MONITORS (FIGURE 2.61) 2.15.1 Condensation Nuclei Counters (CNCs) A CNC is a miniature, continuous-flow counter that takes particles too small to be easily detected, enlarges them to a detectable size, and counts them. Submicrometer particles are grown to supermicrometer alcohol droplets by first saturating the particles with alcohol vapor as they pass through a heated saturator lined with alcohol soaked felt and then condensing the alcohol on the particles in a cooled condenser. Optics focus laser light into the sensing volume. As the droplets pass through the sensing volume, the particles scatter the light. The light is directed onto a photodiode that generates an electrical pulse from each droplet. The concentration of particles equals the number of pulses generated. The counter counts individual airborne particles from sources such as smoke, dust, and exhaust fumes. It operates in three modes, each with a particular application. In the “count’’ mode the counter measures the concentration of these airborne particles. In the “test’’ (or fit test) mode measurements are taken inside and outside a respirator, and a fit factor is calculated. In the “sequential’’ mode the instrument measures the concentration on either side of a filter and calculates filter penetration. This instrument is sensitive to particles as small as 0.02 m, yet it is insensitive to variations in size, shape, composition, and refractive index. An example of this type of monitor is the PortaCount used to determine particulate levels during quantitative fit testing of respirators. Because of shipping regulations for flammable liquids, reagent-grade isopropyl alcohol may have to be purchased locally and used to refill the small plastic alcohol-fill tubes provided with the PortaCount. CTC also stocks and ships this alcohol. For long-term storage (over 14 days), follow the steps listed below: © 2001 CRC Press LLC
Slide 79: 10 µm nozzle cap Seal Porous stainless steel impaction ring Impaction ring support Filter Stainless steel screen Base Outlet Tube Figure 2.59 Exploded view of the PEM. (SKC) • Dry the saturator felt after installing a freshly charged battery. • Pack without adding alcohol. • Allow the instrument to run until the LO message (low battery) or the e—e message (low particle count) appears. • Remove the battery pack from the PortaCount. • Install the tube plugs into the ends of the twin-tube assembly. 2.15.1.1 Calibration Calibrate the counter before and after each use in accordance with the manufacturer’s instructions. © 2001 CRC Press LLC
Slide 80: Figure 2.60 A sampling pump can be used in high flow (750–5000 ml/min) or low flow (5–500 ml/min). Low flow requires an adjustable low-flow holder. (SKC—Model 224-PCXR8) 2.15.1.2 Maintenance Isopropyl alcohol must be added to the unit every 5 to 6 hours of operation, per the manufacturer’s instructions. Take care not to overfill the unit. Under normal conditions a fully charged battery pack will last for about 5 hours of operation. Low-battery packs should be charged for at least 6 hours; battery packs should not be stored in a discharged condition. 2.15.1.3 Photodetection Photodetectors operate on the principle of the detection of scattered electromagnetic radiation in the near infrared (Figures 2.62 and 2.63). Photodetectors can be used to monitor total and respirable particulates. The device measures the concentration of airborne particulates and aerosols, including dust, fumes, smoke, fog, mist. Certain instruments have been designed to satisfy the requirements for intrinsically safe operation in methane-air mixtures. 2.15.1.4 Calibration Factory calibration is adequate. 2.15.1.5 Maintenance When the photodetector is not being operated, it should be stored and sealed in its plastic bag to minimize particle contamination of the inner surfaces of the sensing chamber. © 2001 CRC Press LLC
Slide 81: Figure 2.61 Real-time dust monitoring offers immediate real-time determinations and data recordings of airborne particle concentration in milligrams per cubic meter. Interchangeable size-selective sampling heads allow PM10, PM2.5, or PM1.0 monitoring. (HAZDUST—EPAM-5000 Environmental Particulate Air Monitor) (SKC) After prolonged operation in or exposure to particulate-laden air, the interior walls and the two glass windows of the sensing chamber may become contaminated with particles. Repeated updating of the zero reference following the manufacturer’s procedure will correct errors resulting from such particle accumulations. However, this contamination could affect the accuracy of the measurements as a result of excessive spurious scattering and significant attenuation to radiation passing through the glass windows of the sensing chamber. 2.15.2 Diesel Particulate Matter (DPM) Sampling for particulates is sometimes accomplished using surrogate sampling and analysis. In DPM sampling elemental carbon is used as the basis for evaluating DPM levels (Figures 2.64 and 2.65). © 2001 CRC Press LLC
Slide 82: Figure 2.62 Handheld dust monitors are available in handheld sizes. (SKC) Figure 2.63 This real-time dust monitor can be worn as a personal monitor. (SKC) © 2001 CRC Press LLC
Slide 83: Figure 2.64 NIOSH Method 5040 recommends sampling for DPM by elemental analysis of carbon as a surrogate. A cyclone is used with a 37-mm heat-treated quartz filter and cellulose support pad that has been prepared in a carbon-free humidity-controlled clean room. (SKC) Figure 2.65 DPM sampler assembly in cassette holder. (SKC) 2.16 BIOLOGICALS The world of biological risk assessment is a new and challenging one. Until recently we did not have dynamic methods to test many areas for biological risk. Essentially we relied on shipping sampled material and swabs to laboratory sites for culturing. In some cases we were able to obtain air samples using filter cassettes or impingement onto agar plates with an Anderson air-sampling tower. All of these methods are still used; however, a new tool is now available—an air-sampling device developed to meet the needs of clean rooms and immune-suppressed patient care © 2001 CRC Press LLC
Slide 84: medical facilities. With this new sampling device, the Reuter Centrifugal Sampler (RCS) system, we can insert an instrument the size of a handheld vacuum into locations formerly inaccessible. We can obtain a sample with a designated flow of air, e.g., 50–1000 m3, as a further quantification aid for samples. The samples are impinged upon air-sampling agar plates, where growth may immediately begin. Transfer to laboratory sites allows controlled further growth in biologically safe cabinets. Contact and liquid dip agar plates are used to compare these results to airborne levels. These plates are secured for future laboratory incubation and analysis. At no time are these or the air-sampling media plates left unattended prior to transfer to the laboratory, thereby keeping chain-of-custody intact. Because, unlike chemicals, biologicals can and do multiply through various reproduction means, the use of personnel protective equipment (PPE) is always a requirement during sampling. 2.16.1 General Sampling Protocols The following are step-by-step procedures for mold sampling: 1. Assemble materials and equipment to be used. Segregate materials and equipment to be taken inside the building or area of concern. Use impermeable plastic bags whenever possible to containerize materials and equipment to be taken into the building. Do not use cardboard or other porous containers that cannot be readily decontaminated. 2. Mark each contact sample or strip agar blister pack with a unique sample number using a Sharpie pen. Allow the ink to air dry before overpackaging the blister pack in a baggie. 3. Using a quart or larger size Ziploc freezer bag; overpackage each contact sample or strip agar. 4. Assemble at least 10 of each type of sampling media (contact strips for the RCS) in a large overpackaged baggie. Package no more than 10 agar blister packs together for transfer to a contaminated area. 5. Assemble another bag to contain extra impermeable gloves (latex 6 mil or neoprene) and alcohol wipes. Alcohol wipes can be purchased in small manufactured packages or made up on-site using paper towels and isopropyl alcohol. The made up on-site alcohol towels are more effective for larger decontamination areas. Double bag all sources of alcohol and avoid direct alcohol contact with the agar blister packs. 6. Establish a staging area and set up a decontamination area in a biologically neutral location away from potential biological amplification sites. 7. Don PPE in the following order: • Don first hooded Tyvek. • Don boots. • Don first and second layer of gloves (double gloving is optional in some situations). • Duct tape boot/glove openings at ankles/wrists (optional in some situations). • Don respirator. • Don second hooded Tyvek (optional in some situations). 8. Begin the sampling routine. Sample outside and in all assumed uncontaminated or amplified areas first; then sample into progressively more contaminated areas. © 2001 CRC Press LLC
Slide 85: Use the same protocols for all sampling events, including the same pressure and motion when using contact plates and the same walking routines or static placement when using the RCS. 2.16.2 Contact and Grab Sampling Contact and specimen grab-sampling routines are as follows: 1. Open sample overbag at first location to be sampled. 2. Sample mold by applying the contact plate to the area with some pressure, by swabbing, or by obtaining a small sample of contaminated building (or other) material. 3. Place mold-contaminated item into the sample bag or swab vial. 4. Seal the overbag. 5. Decontaminate gloves if contaminated by direct contact or if pathogenic fungi are suspected. 6. Place used decon pad into small waste bag. 7. Decontaminate spatula or any other tools used. 8. Place decon pad (if used) into small waste bag. Decon pads can be baggies or small pieces of precut plastic. 9. Decontaminate outside of sealed sample bag if contaminated by direct contact or if pathogenic fungi are suspected. 10. Place used decon pad into small waste bag. 11. Repeat steps 1–10 for additional sampling locations. 2.16.3 Reuter Central Fugal System (RCS) Both high-volume and low-volume RCS units are available (see Figures 2.66 and 2.67). The RCS units can be mounted on stands if necessary (Figure 2.68). RCS sampling routines are as follows: Figure 2.66 Biological air sampling instrument. (Biotest Diagnostic Corp. Air Sampler RCS) © 2001 CRC Press LLC
Slide 86: Figure 2.67 RCS centrifugal air sampler. (Biotest Diagnostic Corp.) Figure 2.68 Tripod and remote can be used to sample for biological contamination in ventilation systems. (Biotest Diagnostic Corp.) 1. Open sample overbag at first location to be sampled. 2. Insert RCS agar strip into the RCS impeller assembly. Do not directly touch the agar medium at any time. In the event that the agar is touched, discard that agar strip. 3. Sample mold by running the RCS for the approved time duration. 4. Remove the RCS agar strip from the RCS impeller assembly. Do not directly touch the agar medium at any time. In the event that the agar is touched, discard that agar strip. 5. Place the RCS agar strip into the original sample overbag. 6. Seal the overbag. 7. Decontaminate gloves if contaminated by direct contact or if pathogenic fungi are suspected. 8. Place used decon pad into small waste bag. 9. Decontaminate outside of sealed sample bag if contaminated by direct contact or if pathogenic fungi are suspected. 10. Place used decon pad into small waste bag. 11. Repeat steps 1–10 for additional sampling locations. The RCS in some circumstances may need to be decontaminated between sampling events. In the field the impeller assembly can be cleaned with isopropyl alcohol and thoroughly air-dried in a biologically neutral location. If further decontamination is required, the RCS will need to be decontaminated at the issuing laboratory. © 2001 CRC Press LLC
Slide 87: In some circumstances pathogenic sleeves must be used with the RCS. Do not take the RCS carrying case or battery charger into a contaminated environment. At the conclusion of a sampling event, at a minimum, wipe down the RCS exterior with alcohol wipes. (Contact a CIH for additional decontamination requirements.) Use equipment decon pads to decontaminate temporary lighting and any other large equipment used. Note: Lights are turned off prior to decontaminating. The last set of lights may be decontaminated using handheld flashlights for illumination. 2.16.4 Exit Requirements When exiting the area, • • • • • • • • • • • • • • • • • Seal all used interior decon pads in small waste bag. Exit area. Decontaminate outer Tyvek and respirator with decon wipes. Remove outer Tyvek. Place used Tyvek into large waste bag. Decontaminate inner Tyvek, gloves, and boots. Place used decon pads into waste bag. Remove duct tape from wrists/ankles. Remove boots, gloves, and Tyvek. Place used boots, gloves, and Tyvek into large waste bag. Seal large waste bag. Decontaminate respirator again prior to removal. Place used decon pads into (new) small waste bag. Remove respirator. Use decon pads to decontaminate hands. Place all used decon pads into small waste bag. Bag all disposable equipment for disposal in an approved manner (contact CIH for project specific advice as to disposal). Bag all nondisposable equipment for further decontamination off-site (contact CIH for project specific advice as to disposal). 2.16.5 Static Placement Impingement Less mobile sampling devices are also available. These include the use of filter cassettes to collect all spores—viable and nonviable. The Anderson sampling device has various impaction trays installed to segregate spores on the basis of size. 2.16.6 Bioaerosols When bioaerosols must be collected, extremely high flow rates may be required. The rule in general is that sonic flow requires a 0.5 atm pressure drop (Figure 2.69). As with all pumps, the greater the pressure drop, the faster the intake of air toward that pressure void area. © 2001 CRC Press LLC
Slide 88: Figure 2.69 A noncompensating vacuum pump is capable of maintaining the 0.5 atm pressure drop required for sonic-flow applications. (SKC—Vac-U-Go Sampler) 2.17 RADIATION MONITORS AND METERS 2.17.1 Light Meter The light meter is a portable unit designed to measure visible, UV, and near-UV light in the workplace. The light meter is capable of reading any optical unit of energy or power level if the appropriate detector has been calibrated with the meter. The spectral range of the instrument is limited only by the choice of detector. Steady-state measurements can be made from a steady-state source using the “normal operation’’ mode. Average measurements can be read from a flickering or modulated light source with the meter set in the “fast function’’ position. Flash measurements can be measured using the “integrate’’ function. Exposure of the photomultiplier to bright illumination when the power is applied can damage the sensitive cathode or conduct excessive current. 2.17.1.1 Calibration No field calibration is available. These instruments are generally very stable and require only periodic calibration at a laboratory. 2.17.1.2 Maintenance Little maintenance is required unless the unit is subjected to extreme conditions of corrosion or temperature. Clean the optical unit with lens paper. Detector heads should be recalibrated annually by the manufacturer only. All calibrations are National Institute of Standards and Technology (NIST) traceable. The Ni-Cad batteries can be recharged. Avoid overcharging, which will reduce battery life. © 2001 CRC Press LLC
Slide 89: 2.18 IONIZING RADIATION Because ionizing radiation cannot be detected by the human senses, detection and quantification must be accomplished by specifically designed instruments. All such methods of measurement employ a substance that responds to radiation in a measurable way and a system or apparatus to measure the extent of the response. Most radiation detectors operate by one of two methods: ionization or scintillation. The selection of instruments is based on the type and energy range of the radiation expected on-site. Survey instruments will be chosen for their sensitivity to the type of radiation present in the area to be surveyed. The method of relating the instrument reading to milliroentgens per hour will be included. Some instruments can measure multiple types of radiation and require methods for determining which type of radiation is being measured. For example, neutron detectors for neutron dose can be quantified using boron trifluoride (BF3) detectors. The ionizing radiation survey meter is useful for measuring radon decay products from air samples collected on filters. • The barometric pressure should be noted for ionizing radiation chambers. • Wipe samples collected on a filter can also be counted with this detector, and general area sampling can be done. • The survey meter with the scintillation detector can be used to measure the presence of radon-decay products in a dust sample. 2.18.1 Ionization Detectors Most ionization detectors consist of a gas-filled chamber with a voltage applied; a central wire becomes the anode, and the chamber wall becomes the cathode. Any ion pairs produced by radiation interacting with the chamber move to the electrodes, where they are collected to form an electronic pulse that can be measured and quantified. Depending on the voltage applied to the chamber, the detector may be considered a gas proportional detector, a Geiger-Muller (GM) detector, or an ion chamber. 2.18.1.1 Gas Proportional Detectors Thin-window gas proportional detectors may be used to detect alpha and beta radiation. Distinction between alpha and beta is achieved by adjusting the voltage of the detector. 2.18.1.2 Ion Chamber An ionization chamber is a gas-filled chamber containing an anode and a cathode. As radiation passes through the gas, it ionizes some of the gas molecules. These ion pairs are attracted to the anode and cathode and create an electrical pulse. The pulses are counted, integrated, and displayed on the meter face in roentgens per hour. Ion chambers provide a nearly linear response to gamma and X-ray radiation above a few kiloelectron volts in energy and at radiation levels above 0.1 mR/h. For this reason an ion chamber is the only instrument for quantifying radiation exposures. Ion chambers may be used to quantify the beta, gamma, or X-ray dose at a location. © 2001 CRC Press LLC
Slide 90: Sodium iodide (NaI) scintillation detectors, used on survey meters, provide better counting efficiency for gamma and X-rays, but have a more limited range of energies, depending on the size of the crystal and the density of the window. NaI detectors may be used to detect the presence of gamma radiation, but only if the energy level of the radiation is known, and the correct size crystal is used. 2.18.1.3 GM Detector Because of its versatility and dependability, the GM detector is the most widely used portable survey instrument. A GM detector with a thin window can detect alpha, beta, and gamma radiation. The GM is particularly sensitive to medium-to-high energy beta particles (e.g., as from 32P), X-rays, and gamma rays. The GM detector is fairly insensitive to low-energy X-rays or gamma rays, such as those emitted from 125I, and to low-energy beta particles, such as those emitted by 35S and 14C; it cannot detect the weak betas from 3H. Unlike the ion chamber the GM detector does not actually “measure’’ exposure rate. It instead “detects’’ the number of particles interacting in its sensitive volume per unit time. The readout of the GM is in counts per minute (cpm), although it can be calibrated to approximate milliroentgens per hour for certain situations. With these advantages and limitations a GM detector on a rugged survey meter is the instrument of choice for initial entry and survey of field radiation sources and radioactive contamination. GM detectors are calibrated to one energy level of the electromagnetic spectrum— usually 662 keV, the gamma energy from the decay of 137Cs, and are read out in milliroentgens per hour. GM detector efficiency for radiation at other energies is not linear. GM detectors can be used to detect the presence of radiation, but only as a rough estimate of the dose rate. Beta shields will compensate for blocking betas and reading gamma or X-ray radiation. Subtraction of the gamma or X-ray radiation readings will yield an approximation of the beta contribution. Beta contribution should be read in counts per minute. 2.18.2 Scintillation Detectors Scintillation detectors are based upon the use of various phosphors (or scintillators) that emit light in proportion to the quantity and energy of the radiation they absorb. The light flashes are converted to photoelectrons that are multiplied in a series of dynodes (i.e., a photomultiplier) to produce a large electrical pulse. Because the light output and resultant electrical pulse from a scintillator is proportionate to the amount of energy deposited by the radiation, scintillators are useful in identifying the amount of specific radionuclides present (i.e., scintillation spectrometry). Solid scintillation detectors are particularly useful in identifying and quantifying gamma-emitting radionuclides. NaI scintillation detectors, used on survey meters, provide better counting efficiency for gamma and X-rays, but have a more limited range of energies, depending on the size of the crystal and the density of the window. NaI detectors may be used to detect the presence of gamma radiation, but only if the energy level of the radiation is known, and the correct size crystal is used. The common gamma counter employs a large (e.g., 2 2 or 3 3 ) NaI crystal within a lead-shielded well. The sample vial is lowered directly into a hollow chamber © 2001 CRC Press LLC
Slide 91: within the crystal for counting. Such systems are extremely sensitive, but do not have the resolution of more recently developed semiconductor counting systems. Portable scintillation detectors are also widely used for conducting various types of radiation surveys. Of particular use to researchers working with radioiodine is the NaI thin crystal detector capable of detecting the emissions from 125I with efficiencies nearing 20% (a GM detector is less than 1% efficient for 125I). The most common means of quantifying the presence of beta-emitting radionuclides is through the use of liquid scintillation counting. In these systems the sample and phosphor are combined in a solvent within the counting vial. The vial is then lowered into a well between two photomultiplier tubes for counting. Liquid scintillation counting has been an essential tool of research involving radiotracers such as 3H, 14C, 35S, and 45Ca. One problem that occurs with liquid scintillation counting is determining the efficiency of the system. The low-energy photons produced by the beta particles interacting with the scintillation cocktail are easily shielded from the photomultiplier tubes due to optical and chemical quenching. To account for this artifact, a quench curve must be computed using a set of increasingly quenched standards and a method of determining a quenchindicating parameter for each standard. The quench curve is a graph for a certain nuclide of each standard’s quench-indicating parameter (QIP) vs. the efficiency of the counter. The efficiency for an unknown sample is then determined by measuring its QIP, with the graph determining the counter’s efficiency for that sample. Then use that quantity and the counts per minute of the sample to determine the disintegration rate (dpm) of the sample. Fortunately, most modern counters compute and store quench curves from a single counting of a standard set, use an external standard to determine the QIP, and automatically output sample counts in disintegrations per minute. The other common problem with liquid scintillation counting is chemiluminescence. Certain chemicals when mixed with some scintillation cocktails will cause the cocktail to emit photons, resulting in a higher count rate than actually exists from the radionuclide itself. Rule of thumb: Let scintillation vials wait for a few hours after mixing the cocktail and the material to be assayed to allow for the initial chemiluminescence to be exhausted. 2.18.3 Counting Efficiency The purpose of radiation counting systems is to determine sample activity (microcuries or disintegrations per minute). However, because of numerous factors related to both the counting system and the specific radionuclide(s) in the sample, the radiation detector can never see 100% of the disintegrations occurring in the sample. The counts per minute displayed by the counter must therefore be distinguished from the disintegration rate of the sample. The ratio of the count rate to the disintegration rate expressed as a percent is the efficiency of the counting system. cpm/dpm 100% efficiency (1) Because every counting system will register a certain number of counts from environmental radiation and electronic noise in the counter (i.e., background), a more correct formula is as follows: [(Sample cpm – bkg cpm)/Sample dpm] 100% efficiency (2) © 2001 CRC Press LLC
Slide 92: Example 1 A 1-ml sample of a solution of 125I is counted in a gamma scintillation spectrometer with a window of 15 keV to 75 keV. A 0.1 Ci 125I standard and a background sample are counted along with the solution for 1-min each. The results are as follows: 0.1 Ci 2,220,000 dpm 2.22 106 dpm/ Ci Background (bkg) Standard Sample Efficiency of the counter: 35 cpm 110,658 cpm 3,246,770 cpm [(Sample cpm – bkg cpm)/Sample dpm] [(110,658 – 35)/(0.1 2.22 6 100% efficiency 0.4983 10 dpm/ Ci)] 100% 49.8% efficiency of the counter Activity of the sample: (Sample cpm – Background)/(efficiency (3,246,770 – 35)/[0.4983 2.935 Ci/ml of sample Example 2 A sample containing a 14C-labeled amino acid is counted in a liquid scintillation counter. The sample count rate is 1200 cpm, and the background is 30 cpm. If the counter is 85% efficient for 14C, what is the activity within the sample? Sample cpm – bkg cpm/Sample dpm (1200 1376 dpm 30)/85 2.22 6.2 10 1376 efficiency (2.22 6 dpm per Ci) 10 dpm/ Ci)] 106 dpm/ Ci 4 Ci 2.18.4 Monitoring for Radioactive Contamination Monitoring instruments must be chosen for their sensitivity to the type of radiation to be monitored. A method of relating the instrument reading to microcuries must be included. Monitoring must be performed slowly and at distances of 1 to 2 mm from the surface to detect low-intensity radiations. The monitoring results must be documented and must include the following: © 2001 CRC Press LLC
Slide 93: • • • • • Identification of the instrument used to monitor Name of the person performing the monitoring Location, date, and time of monitoring Results of the monitoring Comments on any factors that might influence the readings 2.18.5 Daily Use Checks Each survey instrument must have an appropriate check source attached or assigned to the instrument. The check source for the instrument must be surveyed immediately after calibration, and the reading must be written on the calibration sticker on the instrument. Before each use of the instrument, the check source must be monitored, and the reading compared to the reading noted on the calibration sticker. Any meter not measuring within 10% of the reading on the calibration sticker must be tagged as requiring maintenance and must not be used until maintenance and recalibration have been performed. Surveys must be performed slowly; the instrument needs time to integrate and display the measurement. Survey results must be documented and must include the following: • • • • • Identification of the instrument used to perform the survey Name of the person performing the survey Location, date, and time of the survey Results of the survey Comments on any factors that might influence the survey 2.18.6 Survey Instrument Calibration Survey instruments must be calibrated periodically using procedures outlined in the instrument manual, within the following guidelines: • All sources used to calibrate instruments must be traceable to NIST. • The survey meter and the probe must be calibrated as a unit. If probes are changed, the unit must be recalibrated prior to use. • Instruments must be calibrated at least annually. • Instruments must be calibrated after every maintenance or repair operation. The date of calibration, the date the next calibration is due, and the initials of the person performing the calibration must be written on a calibration sticker attached to the instrument. 2.19 NONIONIZING RADIATION Electromagnetic fields (EMFs) produced by computer terminals, cellular phones, electric blankets, and power lines can be measured. Microwave radiation, whether used for communication, electron wave propulsion, or food warming, can also be measured. EMFs are generated any time charged particles move through a medium. Two fields are actually produced, one electric and one magnetic. Both are always found together. © 2001 CRC Press LLC
Slide 94: The earth itself is the largest source for a magnetic field, and lightning generates one of the strongest electric fields. Electricity transmitted through a wire produces an EMF proportional in size to the current flow and the voltage drop. Another issue associated with EMFs is the corona phenomenon, where air around a high voltage power line is ionized and interferes with TV and radio reception. This ionization can also generate ozone that may be a health concern. The electromagnetic spectrum is very broad and consists of low-frequency, low-energy waves, such as those generated by power lines, through high-energy, high-frequency cosmic rays. • The wavelength of most interest is around 60 Hz. This frequency is the one most commonly used in the United States for electrical power transmission and falls into a range known as extremely low frequency EMF. The extremely low frequency EMF range is from 5 Hz to 2000 Hz. These waves are extremely long and can be easily shielded or attenuated. • Cellular phones broadcast radio signals at around 850 MHz. These radio signals are equivalent to most television transmission frequencies. Cellular phones operate at a much higher frequency than most household sources of EMF. • Ionizing radiation, such as X-rays, have a frequency of around 2.5 1015 Hz. Ionizing radiation, in very high doses, is known to lead to an increase in cancer incidence. 2.19.1 Guidance No legally enforceable exposure standards are in place for any nonionizing radiation. The non-Ionizing Radiation Committee of the International Radiation Protection Association recommends the following standards for 60 Hz EMF: Magnetic field strength: • 5 Gs—occupational exposure • 1 Gs—public exposure Electric field strength: • 10,000 V/m3—occupational exposure • 5,000 V/m3—public exposure Surveys of ten commonly used video display terminals gave readings in the following ranges: • Magnetic field strength of 0.0006 to 0.0077 Gs • Electric field strength of 1.6 to 15 V/m3 2.19.2 Broadband Field Strength Meters Broadband field strength meters are available for measuring electromagnetic radiation in the frequency range from 0.5 MHz to 6000 MHz. Each meter comes with probes for measuring either magnetic or electric field strength, batteries, headset, and carrying case. This unit is designed for laboratory and field use to measure magnetic and electric fields near radio frequency (RF) induction heaters, RF heat sealers, radio and TV antennas, or any other RF sources. © 2001 CRC Press LLC
Slide 95: • All units have automatic zeroing. There is no need to place the unit in a zero-field condition to zero it. • All units have a peak memory-hold circuit that retains the highest reading in memory. • All units operate with either electric (E) or magnetic (H) field probes based on diode-dipole antenna design. Total field strength is measured at the meter regardless of the field orientation or probe-receiving angle. The diode-dipole antenna design of the probe is much more resistant to burnout from overload than the thermocouple design of probes used with other meters. 2.19.2.1 Calibration No field calibration is available. Periodic calibration by a laboratory is essential. 2.19.2.2 Maintenance No field maintenance is required other than battery-pack charging or replacement. © 2001 CRC Press LLC
Slide 96: CHAPTER 3 Calibration Techniques This chapter contains theoretical and real-world discussions about the intricacies of calibration. It gives special emphasis to situations where the knowledge of calibration techniques is a prerequisite for sampling adequacy. Calibration is the means used to provide evidence that instrumentation is working accurately and that results are reliable and repeatable within the tolerance levels prescribed for these instruments. The calibration of real-time instruments is very specific, and manufacturer’s instructions must be followed. Increasingly, instrumentation is calibrated using electronic circuitry, with empirical tests against standards in accordance with the manufacturer’s requirements at prescribed intervals. Collection efficiency must also be taken into account when calibration curves are developed. As filters, cartridges, or sorbent tubes load, air intake and calibrated airflow volumes across the media can be expected to change (Figure 3.1). 3.1 CALIBRATION REQUIREMENTS Instrument calibration records must be reviewed periodically by the users to assess accuracy of documentation and to evaluate instrument performance. Assessment is based on the instrument operating instructions and knowledge of the user. • Users will check minimum calibration frequency requirements for the instrument and calibrate according to the applicable operating instruction manual. • Calibrating the instrument at the worksite under actual field conditions is an important requirement. • Air-sampling instrument readings for calibration will be corrected for temperature and barometric pressure. Record calibration and challenge results as follows in the field logbook and include the following information: • • • • Instrument identification Date (if not on page in logbook) Precalibration readings as found or as set Readings after calibration and span settings, if applicable © 2001 CRC Press LLC
Slide 97: 2 4 6 8 10 Figure 3.1 SKC cyclone sampler at 2.6 l/min collection efficiency vs. aerodynamic diameter. • Calibration gas (challenge) used and lot number • Signature of person performing calibration 3.1.1 Calibration Assurance The user will transport the instrument to the field in its carrying case or by other means that will adequately protect the instrument. All devices to be used in the field sampling train must be in-line during calibration (Figure 3.2). Relevant information such as the type of instrument to be used, frequency of monitoring, and specific warning and action levels are found in the site safety and health plan or Activity Hazard Analysis (AHA) written for the specific job site. The user must follow these requirements: • Users are expected to follow the specific manufacturer’s operating instruction manual for the instrument being used. The user takes a field copy of the operating instruction manual into the field with the instrument. • Prior to entering a contaminated zone, the user will take appropriate precautions to prevent contamination of the instrument, e.g., using plastic bags or filters. • The instrument is used in accordance with the applicable operations and maintenance (O&M) manual and site safety and health plan. • Data are recorded in the field logbook. © 2001 CRC Press LLC
Slide 98: AIRCHEK SAMPLER SAMPLE PERIOD MINUTES START HOLD FLOW AND BATTERY CHECK ¤ INTRINSICALLY SAFE PORTABLE AIR SAMPLING PUMP FOR USE IN HAZARDOUS LOCA TIONS CLASS I, GROUPS A B C D AND CLASS II, GROUPS E F G AND CLASS III, TEMPERATURE CODE T3C. UL LISTED 124U 5 4 3 2 1 SET-UP MODE AIRCHEK SAMPLER MODEL 224-PCXR8 WARNING - SUBSTITUTION OF COMPONENTS MAY IMPAIR INTRIN SIC SAFETY. USE ONLY UL LISTED PORTABLE AIR SAMPLING PUMP BATTERY PACK MODEL P21661 DIGIT SELECT TOTAL ELAPSED TIME DIGIT SET PUMP RUN TIME ON FLOW SERIAL NO. SKC INC. EIGHTY FOUR PA 15330 ADJ Figure 3.2 A primary standard flowmeter connected to a sampling train. (SKC) 3.1.2 Decontamination Decontamination of instruments is necessary to remove contaminants present at a site. The user is expected to take the proper steps to assure the instrument is clean prior to leaving a contaminated zone. A radiation release sticker may be required depending on the circumstances of radioactive contamination on-site. Decontamination procedures will vary depending on the individual contaminants and circumstances involved. Steps may be as simple as wiping down the instrument probe with soap and water or as involved as disassembly and thoroughly cleaning with decontamination agents. Decontaminate the instrument in accordance with the site safety and health plan decontamination procedures or instructions provided by air monitoring professionals. 3.1.3 Maintenance Users should not attempt field repairs other than preventive maintenance, cleaning, adjustments, or decontamination. Major repairs must be done by a qualified instrument technician or the factory. Refer to the O & M manual for maintenance instructions. Flow-rate holders also require frequent maintenance to assure consistent operation (Figure 3.3). • Battery charging will be done in accordance with the manufacturer’s O&M manual to prevent overcharging or possible damage to the equipment. © 2001 CRC Press LLC
Slide 99: Figure 3.3 Single, double, triple, and quadruple adjustable low flow holders. (SKC) • Manufacturer’s preventive maintenance procedures and major repairs by the factory or instrument technician will be recorded in the field logbook or calibration logs for that instrument. • After field maintenance, instrument calibration is invalidated, and recalibration is necessary prior to use. The terms primary and secondary calibration devices are used in field calibration. Primary calibration means that a physical phenomenon whose progression is dictated by the laws of physics is measured for quantification. Such a physical phenomenon is the time required for a bubble to move up a glass tube or the time required for a gas to evaluate a chamber. Secondary calibration involves the use of equipment previously calibrated against a primary standard. Such equipment is often the proper choice because primary standards often cannot be readily transported and relied upon under field conditions. 3.2 MANUAL BURET BUBBLE METER TECHNIQUE (PRIMARY CALIBRATION) When a sampling train requires an unusual combination of sampling media (e.g., glass fiber filter preceding impinger), the same media/devices should be in-line during calibration. Calibrate personal sampling pumps before and after each day of sampling (Figure 3.4). 3.2.1 Bubble Meter Method For the Bubble Meter Method use the following procedures: 1. Allow the pump to run 5 min prior to voltage check and calibration. 2. Assemble the polystyrene cassette filter holder using the appropriate filter for the sampling method. 3. If a cassette adapter is used, care should be taken to prevent contact with the backup pad. 4. Note: When calibrating with a bubble meter, the use of cassette adapters can cause moderate to severe pressure drop in the sampling train, which will affect the calibration result. If adapters are used for sampling, then they should be used during calibration. © 2001 CRC Press LLC
Slide 100: Figure 3.4 This portable standard flowmeter can be used in the office or laboratory, and in the field. (SKC) 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Connect the collection device, tubing, pump, and calibration apparatus. A visual inspection should be made of all Tygon® tubing connections. Wet the inside of a 1-l burette with a soap solution. Turn on the pump and adjust the pump rotameter to the appropriate flow-rate setting. Momentarily submerge the opening of the burette in order to capture a film of soap. Draw two or three bubbles up the burette so the bubbles will complete their run. Visually capture a single bubble and time the bubble from 0 to 1000 ml for highflow pumps or 0 to 100 ml for low-flow pumps. The timing accuracy must be within 1 s of the time corresponding to the desired flow rate. If the time is not within the range of accuracy, adjust the flow rate and repeat steps 9 and 10 until the correct flow rate is achieved. Perform steps 9 and 10 at least twice in any event. While the pump is still running, mark the pump or record (on the calibration record form) the position of the center of the float in the pump rotameter as a reference. Repeat the procedures described above for all pumps to be used for sampling. The same cassette and filter may be used for all calibrations involving the same sampling method. Calibration of multiple tubes, whether in series or in parallel, is sometimes required. Any flow adjustment mechanisms and critical orifices must also be installed in the sampling train during these calibrations. When flexible tubing is used, it must be consistently used in all applications during sampling events (Figure 3.5). 3.3 ELECTRONIC FLOW CALIBRATORS Electronic flow calibrators are high-accuracy, electronic bubble flowerets that provide instantaneous airflow readings and a cumulative averaging of multiple samples. © 2001 CRC Press LLC
Slide 101: Figure 3.5 Two sorbent sampling tubes in series with a single adjustable low-flow holder. (SKC) • These calibrators measure the flow rate of gases and present the results as volume per unit of time. • These calibrators may be used to calibrate all air-sampling pumps. • The timer is capable of detecting a soap film at 80- s intervals. • This speed allows under steady flow conditions an accuracy of 0.5% of any display reading. • Repeatability is 0.5% of any display. • The range with different cells is from 1 ml/min to 30 l/min. • Battery power will last 8 h with continuous use. Charge for 16 h. These meters can be operated from A/C chargers. When a sampling train requires an unusual combination of sampling media (e.g., glass fiber filter preceding impinger), the same media and devices should be in-line during calibration (Figure 3.6). 3.3.1 Cleaning Before Use Before using an Electronic Flow Calibrator: • Remove the flow cell and gently flush it with tap water. The acrylic flow cell can be easily scratched. • Wipe with cloth only. • Protect center tube, where sensors detect soap film, from dirt and scratches. • Never clean with acetone. Use only soap and warm water. © 2001 CRC Press LLC
Slide 102: Figure 3.6 The electronic flow calibrator using soap bubbles is easy to use and suitable for field use. (SKC) When cleaning a flow cell prior to storage, allow it to air-dry. If stubborn residue persists, it is possible to remove the bottom plate. Squirt a few drops of soap into the slot between base and flow cell to ease residue removal. 3.3.2 Leak Testing The system should be leak checked at 6-in. H2O by connecting a manometer to the outlet boss and evacuate the inlet to 6 in. H2O. No leakage should be observed. 3.3.3 Verification of Calibration The calibrator is factory calibrated using a standard traceable to the NIST, formerly called the NBS. • Attempts to verify the calibrator against a glass 1-l burette should be conducted at 1000 ml/min for maximum accuracy. • The calibrator is linear throughout the entire range. © 2001 CRC Press LLC
Slide 103: 3.3.4 Shipping and Handling When transporting, especially by air, one side of the seal tube that connects the inlet and outlet boss must be removed for equalizing internal pressure within the calibrator. Do not transport the unit with soap solution or storage tubing in place. 3.3.5 Precautions and Warnings Avoid the use of chemical solvents on the flow cell, the calibrator case, and the faceplate. Generally, soap and water will remove any dirt. • Never pressurize the flow cell at any time with more than 25-in. water pressure. • Do not charge batteries longer than 16 h. • Do not leave A/C adapter plugged into calibrator when not in use to avoid damage to the battery supply. • Close-fitting covers help to reduce evaporation of soap in the flow cell when it is not in use. • Do not store flow cell for 1 week or longer without removing soap. • Clean the flow cell and store dry. Calibrator soap is a precisely concentrated and sterilized solution formulated to provide a clean, frictionless soap film bubble over the wide, dynamic range of the calibrator. The sterile feature of the soap is important to prevent residue buildup in the flow cell center tube, which could cause inaccurate readings. The use of any other soap is not recommended. 3.4 ELECTRONIC BUBBLE METER METHOD Various electronic meters are available that mimic the performance of the bubble burette. Most use shortened bubble tubes and calculate this shortened tube length as though the bubble burette was the standard size. The protocol for using these meters is as follows: • Connect the collection device, tubing, pump, and calibration apparatus. • Visually inspect all Tygon® tubing connections. • Wet the inside of the electronic flow cell with the soap solution by pushing on the button several times. • Turn on the pump and adjust the pump rotameter, if available, to the appropriate flow rate. • Press the button on the electronic bubble meter. Visually capture a single bubble and electronically time the bubble. The accompanying printer will automatically record the calibration reading in liters per minute. • Repeat these steps until two readings are within 5%. If necessary, adjust the pump while it is still running. • Repeat the procedures described above for all sampling pumps. The same cassette and filter may be used for calibrations involving the same sampling method. For sorbent tube sampling, however, the sorbent tube to be used must be used during the calibration. © 2001 CRC Press LLC
Slide 104: Note: When calibrating with a bubble meter, cassette adapters can cause moderate to severe pressure drop at high-flow rates in the sampling train and affect the calibration result. • If adapters are used for sampling, they should also be used for calibrating. • Caution: Nylon adapters can restrict airflow due to plugging. • Stainless-steel adapters are preferred. 3.5 DRY-FLOW CALIBRATION With the advent of computer chip and microcircuitry technology, dry-flow calibration of instruments is now possible. Dry-flow calibrators measure the flow across near frictionless composite pistons (Figure 3.7). For some pumps, an adapter must be used between the pump and the dry-flow calibration instrument (Figure 3.8). In addition to measuring flow rates, the calibration devices can also record time, date, employee names, pump ID, sample ID number, and other programmed information (Figure 3.9). 3.6 PRECISION ROTAMETER METHOD (SECONDARY) The precision rotameter is a secondary calibration device. If used in place of a primary device such as a bubble meter, take care that any error introduced is minimal and noted (Figure 3.10). Figure 3.7 An electronic flow calibrator is available that does not use soap; instead it uses a graphite/carbon-composite piston that rises in the chamber like the bubble. (Bios International Corp.) © 2001 CRC Press LLC
Slide 105: Figure 3.8 An electronic adapter is available to automatically calibrate an air sampling pump. (SKC—AirCheck ® 2000 air sampling pump, CalCheck ® Communicator with DC-Lite calibrator). (Bios International Corp.) Figure 3.9 The electronic standardization and communication module provides time/date stamping; employee, pump, and sample ID numbers; volumetric flow rate readings; and readings at user-defined time intervals for flow stability testing. (Bios International Corp.) © 2001 CRC Press LLC
Slide 106: Figure 3.10 Secondary standard rotameters are used in the field to calibrate air-sampling pumps. Rotameters are calibrated to a primary standard. Flow rates must be corrected for standard temperature and pressure. (SKC) 3.6.1 Replacing the Bubble Meter with a Precision Rotameter The precision rotameter may be used for calibrating the personal sampling pump in lieu of a bubble meter, provided it is • Calibrated regularly, at least monthly, with an electronic bubble meter or a bubble meter. • Disassembled, cleaned as necessary, and recalibrated. (It should be used with care to avoid dirt and dust contamination, which may affect the flow.) • Not used at substantially different temperature and/or pressure levels than when the rotameter was calibrated against the primary source. • Used in such a way that the pressure drop across the rotameters is minimized. If altitude or temperature at the sampling site is substantially different from that at the calibration site, it is necessary to calibrate the precision rotameter at the sampling site. 3.7 SPAN GAS Span gas of known concentration can be used to calibrate detectors. An example is the use of span gas in a PID. A known concentration of a gas that readily ionizes in the PID energy lamp’s electron voltage is drawn into the ionization chamber. Essentially this gas spans the distance between the anode and cathode sides of the ionization chamber. The detector must therefore detect this span and send an appropriate electrical signal to the readout device. The electrical output to the detector readout for the PID is then adjusted. The reason for this adjustment or calibration is that with a known concentration of a gas that will © 2001 CRC Press LLC
Slide 107: ionize at a known voltage, the PID should detect and read out the same as the concentration listed on the compressed gas bottle. Isobutylene has an IP of 9.8 eV and is the usual calibration gas of choice for PIDs. Historically, benzene was used (same IP of 9.8 eV); however, that use was discontinued due to benzene’s carcinogenic and toxic effect potential. Remember that after the ionization cycle, the gases reform and are exhausted from the PID reaction chamber. The other exposure route occurred when the calibration gas was attached to the sampling train. 3.8 BUMP TESTING Bump testing is used to check sensor operation. This sensor check is not a substitute for the calibration of sensors. However, bump testing can • Provide an indication of sensor reliability under field conditions. • Indicate when calibration is required. • Test all sensors simultaneously. Bump testing involves the use of a bump test gas cylinder filled with known concentrations of various gaseous challenge agents. These gases each provide a known percentage or parts per million component. The gas cylinder is attached to an instrument’s inlet portal or diffusion grid, and the instrument’s detector readouts are compared to the bump gas known concentration (Figure 3.11). Figure 3.11 Bump testing needs to be performed regularly to ensure that real-time air monitoring instrumentation is functioning properly. (MSA) © 2001 CRC Press LLC
Slide 108: CHAPTER 4 Statistical Analysis and Relevance This chapter contains theoretical and real-world discussions about statistical analysis. It gives special emphasis to situations where knowledge of statistical relevance is a prerequisite for sampling adequacy. It also illustrates the difference between log-normal and normal distribution and parametric monitoring data. 4.1 DEFINITIONS In statistical analysis and relevance, certain standard definitions are used. The following standard definitions and examples illustrate the basic concepts. • Accuracy: Agreement of the measured value (i.e., empirical value) and the “true value’’ (i.e., accepted reference value) of the sample given valid sampling techniques, proper sample preparation, and reliable and accurate instrumentation and/or other procedures. Accuracy is often estimated by adding (or “spiking’’) known amounts of the target parameters. For asbestos quality assurance (QA) sampling, accuracy is evaluated by comparing analyses of duplicate samples that have been evaluated in proficiency in analytical testing (PAT) round robins (for air samples) or NIST National Voluntary Laboratory Accreditation Program (NVLAP) proficiency testing (for bulk and transmission electron microscopy [TEM]). Accuracy is a measure of the bias of the method and may be expressed as the difference between two values, a ratio, or the percentage difference. • Analysis: Combination of sample preparation and evaluation. • Audit: Systematic determination of the function or activity quality. • Bias: Systemic error either inherent in the method or caused by measurement system artifacts or idiosyncrasies. • Blind sample: Presented to the laboratory as indistinguishable from field samples (syn: performance audit samples). All field blanks are to be presented to the laboratory as blind samples for asbestos air samples. • Calibration: Comparative procedure in which singular measurements are evaluated against an accepted group of measurements. The evaluation may be against a primary, intermediate, or secondary standard. © 2001 CRC Press LLC
Slide 109: • Calibration curve: Range over which measurement can take place (syn: standard curve, multipoint calibration). • Calibration standard: Instruments or other measurement techniques used to evaluate the measurement system. Ideally, these standards do not directly incorporate or use the target parameters to be measured. • Chain-of-custody: Defined sample custody procedures that must be followed to document the transition from field collection to subsequent transfer sites (common carriers, laboratories, storage facilities, etc.). • Check standard: Used to verify that the initial standard or calibration curve remains in effect. It ideally incorporates standard materials (syn: daily standard, calibration check or standard, reference standard, control standard, single point response factor, single point drift check). • Comparability: Confidence with which one set of empirical data can be compared to another. • Completeness: Amount of valid data obtained from a measurement system compared to the amount expected. • Data quality: Totality of data parameters that identify ability to satisfy or represent a given condition; includes accuracy, precision, representativeness, and comparability. • Data reduction: Using standard curves to interpret raw data. • Data validation: Review process that compares a body of data against a set of criteria to provide data adequacy assurance given the data’s intended use; includes data editing, screening, checking, auditing, verification, certification, and review. • Detection limit: Minimum target parameter quantity that can be identified, i.e., distinguished from background or “zero’’ signal. • Double-blind sample: When neither the composition nor identification of the sample is known to the analyst. • Duplicate sample (field or laboratory): Sample divided into two portions, with both portions carried through the sample preparation process at the same time. For asbestos air samples, field duplicates are air samples collected at the same time as the compliance air samples, and lab duplicates are portions of one filter that are fixed and analyzed separately. • Environmentally related measurements: Field or laboratory investigations that generate data involving chemical, physical, or biological parameters characteristic of the environment. • Field blanks: Generated at the time of sampling, field blanks provide a check on contamination, starting with the sampling process and proceeding through the full analysis scheme. For asbestos fiber concentration sampling, field blanks are filter cassettes transported to the site and exposed to ambient conditions. The filter caps are removed from the filter cassettes; however, a vacuum air pump is not used to pull air across the filter cassettes. Thus, the cassettes are exposed to the environmental airstream of the surrounding environment outside the asbestos control area. • Good laboratory practices: Performing a basic laboratory operation or activity so as not to influence data generation quality. • Instrument blank: Used to obtain information on instrument aberration absence/presence. The measurement instrument is presented with materials normally within the instrument and cycled through the measurement sequence. The resulting signal is then defined as the baseline instrument signal level. • Internal standard: A nontarget parameter added to samples just prior to measurement to monitor variation in sample introduction and stability and to normalize © 2001 CRC Press LLC
Slide 110: • • • • • • • • • • • data for quantitation purposes. Internal standards are not usually used in bulk (phase light microscopy [PLM]) or phase contrast microscopy (PCM); however, these standards may be applicable to TEM protocol. Laboratory blank: Prepared in the laboratory after receipt of samples from the field. These blanks are prepared using a material assumed not to contain the target parameter. Lab blanks for asbestos sampling are filter membranes obtained from filter cassettes that have been retained in the laboratory without removal of the filter cassette caps. The lab blank is a check on all the chemicals and reagents used in the method as well as the influence of the general laboratory environment (syn: analytical blank, system blank, method blank, process blank). Measurement: Creating quantitative data from a prepared sample. Method check sample: Prepared in the laboratory by spiking a clean reference matrix with known quantities of the target parameters. For asbestos air-sampling analysis, method check samples are previously prepared filters evaluated by separate analysts within the same laboratory. These duplicate analyses are defined in the National Institute of Occupational Safety & Health (NIOSH) 7400 method as quality assurance, and the acceptable statistical parameters are outlined therein. Method detection limit: Minimum quantity that a method (i.e., both sample preparation and target parameter measurement steps) can be expected to distinguish from background or “zero’’ signal. This limit takes into account losses during preparation and measurement and instrument sensitivity that may contribute to qualification or quantification of results. This limit does not apply to physical parameters (i.e., density, temperature). Performance evaluation (PE) sample: Sample with known “true’’ values that is presented to the laboratory as a “performance evaluation sample.’’ These samples are biased by the analyst’s knowledge of the intent of the sample. For asbestos air-sampling analysis, “true’’ value samples may be defined as the PAT samples with their inclusive statistical ranges. Precision: Measure of the reproducibility of a set of results obtained under similar conditions. Precision is determined by multiplicate analysis of samples, duplicates, replicates, or splits. Standard deviation is used as a measure of precision. Procedure: Systematic instructions and operations for using a method of sampling or measurement. Proficiency sample: Samples for which known composition values are available for accuracy comparisons. The composition values may be qualitative, quantitative, or statistical ranges of acceptable qualitative/quantitative results. Quality assurance: An orderly assemblage of management policies, objectives, principles, and general procedures by which a laboratory outlines the methods used to produce quality data. QA is an intralaboratory function. Note: The NIOSH 7400 method defines QA in terms of both intralaboratory and interlaboratory methods and/or sequencing. However, for the purposes of specified QA/quality control (QC) documents, interlaboratory methods are defined as QC. Quality control: Routine application of procedures used to develop prescribed performance standards in the monitoring and measurement of standards. QC is an interlaboratory function. QC samples: Analyzed concurrently with field samples to insure that analytical systems are operating properly, i.e., in control. These samples provide an estimate of the precision and accuracy of the sampling and analysis system. QC samples for asbestos sampling are sent between laboratories for interlaboratory comparisons of methodology and analytical proficiency. © 2001 CRC Press LLC
Slide 111: • Quality of method: Degree to which the method functions free of systemic error, bias, and random error. • Quantitation limits: Maximum and minimum levels or quantities of a reliably quantified target parameter. These limits are bounded by the standard curve limits and are generally related to standard curve data. • Reagent blank: Used to identify contamination sources. These blanks incorporate specific reagents during sample preparation to identify lab blank contaminate sources (syn: dilution blank). • Recovery/percent recovery: Generally used to report accuracy based on the measurement of target parameters, comparison of these concentrations, and correlating these measurements to the predicted amounts. Recovery in asbestos air sampling is the statistical percentage differential observed during accuracy evaluation (i.e., percentage difference in fiber concentrations). • Replicate samples (field or laboratory): A sample is divided into two portions and is processed as two completely separate and nonparallel samples, i.e., prepared and analyzed at different times or by different people. Field replicates in asbestos air sampling are defined as filters that are obtained from two separate filter cassettes drawn separately or from a y-juncture. These are then transported, fixed, and analyzed separately. Lab replicates are taken from a singular filter, which is sectioned, fixed, and analyzed separately. • Representativeness: Degree to which data accurately and precisely represent a parameter variation characteristic at a sampling point and portray an environmental condition. • Sample custody: Verification and documentation procedure for the transfer of samples from the field to the laboratory, within the laboratory, and to the final storage or disposal destination. • Sample Operation Procedure (SOP): Procedure adopted for repetitive use when performing a specific measurement or sampling operation. • Sample preparation: Transformation of the sample into appropriate forms for transfer and/or measurement. • Sampling: Removal of a process stream representative portion or a portion of a larger quantity of material for subsequent evaluation. • Sensitivity: An instrument’s detection limit given the minimum quantity of a target parameter that can be consistently identified, i.e., distinguished from background or “zero’’ signal by the instrument; ideally established using the materials that are used for standardization. • Split samples (field or laboratory): A sample, divided into aliquots, that is sent to a different laboratory for preparation and measurement. These split samples may be replicates or duplicates that are then defined as splits when sent to another laboratory for QC analysis. For asbestos air samples this shipment involves either the shipping of capped filter cassettes (field split) or the shipping of fixed slides (lab split). • Standard materials: Materials, such as mixtures of the target parameters at known concentration and purity, used to carry out standardizations. For asbestos air sampling these materials may be PAT samples. • Standardization: Establishing a quantitative relationship between known target parameters input and instrument readout. • Target parameters: Entity for which qualitative or quantitative information is desired. © 2001 CRC Press LLC
Slide 112: • Trip blanks: Essentially field blanks that do not have the caps removed. These blanks provide insight into the contamination generated as a result of the shipping process. These blanks are generally not required for asbestos sample shipment. 4.2 EXAMPLE—OUTLINE OF BULK SAMPLING QA/QC PROCEDURE Bulk sample analysis procedures are defined in the NIOSH method for PLM and the NIOSH 7402 method for TEM. Because bulk sample analysis is done by an independent laboratory off-site, this QA/QC document will not address bulk sampling as a fieldverified procedure. The NVLAP is currently used to ascertain laboratory effectiveness. The contractor must provide proof that NVLAP certification is current for the laboratory designated to receive both the initial bulk samples and the 10% bulk sample duplicates. The optical properties and ID of fibers are as follows: • Determine 13 specific items for asbestos. • ID other fibers with some optical data. • ID matrix components. In addition record • Special procedures or solvents • Sampling of layers • Deviations from EPA test procedure The 10% bulk sample duplicates are provided by physically dividing 10% of the samples collected. This division should occur concurrently with the collection of field samples. The rationale for splitting the samples at a time and location removed from the field collection site must be provided. All field collection procedures, sample labeling, and transport and disposal procedures must be addressed in the QA/QC document. Provide the rationale for the classification and remediation of errors. The following is a sample of error classification: Major Error • • • • False positive False negative (asbestos actually 1%) Incorrect asbestos type classification Analysis quantification in error by 25% Minor Error • • • • Incorrect ID of tremolite or actinolite as another type of asbestos False negative (asbestos actually 1% or trace) Analysis quantification in error by 15% Incomplete lab data sheets (repeated omissions may equal major error) Corrective Steps—Major Errors • Take immediate action. © 2001 CRC Press LLC
Slide 113: • • • • • Review documents for transcription errors. Review sample, especially matrix description. Reanalyze sample; submit to other labs for analysis. Check environment for contamination and out of calibration equipment. For misidentification of asbestos species review literature and reference samples. Corrective Steps—Minor Errors • One to two weeks or after monthly summaries • Steps 1 through 4 above. • Review to determine if error is systematic estimation bias, then retrain on estimation techniques and/or sample preparation techniques. • Completed data sheets are required; frequent omissions should be considered a major error. • Review sampling and stereomicroscope sample preparation procedures. • To recalibrate estimation techniques, reanalyze known samples; review literature on estimation training. • Review; retrain on reference samples, especially in problem matrix mixtures. Review specific problems like tremolite or crocidolite samples. • Review lab’s special sample preparations for Vinyl Asbestos Tile (VAT) or tar matrix materials. Practice on known materials including blanks. 4.3 EXAMPLE—OUTLINE OF THE NIOSH 7400 QA PROCEDURE 4.3.1 Precision: Laboratory Uses a Precision of 0.45 Current guide specifications give a precision of 0.45 as acceptable in calculation of the 95% upper confidence level (UCL). Using a precision of 0.45 implies that the standard deviation divided by the arithmetic mean gives a value of 0.45. This ratio is variously called the coefficient of variation (CV) or the SR in the NIOSH 7400 method. With the 90% confidence interval of mean count, which includes a subjective component of 0.45 plus the Poisson component, 0.45 precision implies that reproducibility of results is questionable. Thus, the use of the 0.45 value in the calculation of the UCL must be clearly identified. For compliance purposes the following equation is acceptable: Measured (air quality) (0.45) (1.645) concentration (standard) The QA procedures given in the NIOSH 7400 method must be referenced in a discussion of the 0.45 precision value used. Detailed outlines of the intralaboratory procedures are not necessary. Proof of acceptable PAT participation (i.e., judged proficient for the target parameter in four successive round robins) as administered by the American Board of Industrial Hygiene (ABIH) must be provided. 4.3.2 Precision: Laboratory Uses a Precision SR that is Better Than 0.45 When a precision better than 0.45 is suggested, an outline of the NIOSH 7400 QA procedures used and a current CV curve must be provided in addition to the proof of acceptable PAT participation. The outline must include the following: © 2001 CRC Press LLC
Slide 114: • Document the laboratory’s precision for each counter for replicate fiber counts by using this procedure. • Maintain as part of the QA program a set of reference slides to be used daily. These slides should consist of filter preparations including a range of loading and background dust levels from a variety of sources including both field and PAT samples. —Have the QA officer maintain custody of the reference slides and supply each counter with a minimum of one reference slide per workday. Change the labels on the reference slides periodically so that the counter does not become familiar with the samples. —From blind repeat counts on the reference slides, estimate the laboratory intraand intercounter SR. —Determine separate values of relative standard deviation for each sample matrix analyzed in each of the following ranges. Maintain control charts for each of these data files. • 15 to 20 fibers in 100 graticule fields • 20 to 50 fibers in 100 graticule fields • 50 to 100 fibers in 100 graticule fields • 100 fibers in less than 100 graticule fields Note: Certain sample matrices (e.g., asbestos cement) have been shown to give poor precision. Prepare and count field blanks along with the field samples. Report counts on each field blank. Note 1: The identity of blank filters should be unknown to the counter until all counts have been completed. Note 2: If a field blank yields greater than 7 fibers per graticule fields, report possible contamination of the samples. • Perform blind recounts by the same counter on 10% of filters counted (slides relabeled by a person other than the counter). Use the following test to determine whether a pair of counts by the same counter on the same filter should be rejected because of possible bias: • Discard the sample if the absolute value of the difference between the square roots of the two counts (in fiber/mm2) exceeds 2.8 (x) 2 8 SR, where x the average of the square roots of the two fiber counts (in fiber/mm2) and SR one half the intracounter relative standard deviation for the appropriate count range (in fibers). Note 1: Fiber counting is the measurement of randomly placed fibers that may be described by a Poisson distribution; therefore, a square root transformation of the fiber count data will result in approximately normally distributed data. Note 2: If a pair of counts is rejected by this test, recount the remaining samples in the set and test the new counts against the first counts. Discard all rejected paired counts. It is not necessary to use this statistic on blank counts. The analyst is a critical part of this analytical procedure. Care must be taken to provide a nonstressful and comfortable environment for fiber counting. An ergonomically designed chair should be used. With the microscope eyepiece situated at a comfortable height for viewing. External lighting should be set at an intensity level similar to the illumination level in the microscope to reduce eye fatigue. Counters should take 10–20 min © 2001 CRC Press LLC
Slide 115: breaks from the microscope every 1 to 2 hours to limit fatigue. During these breaks both eye and upper back/neck exercises should be performed to relieve strain. Calculation of compliance uses the same equation with the substitution of a different value for 0.45. Use of this different value requires prior approval. All filters selected for the 10% recount should be randomly selected, rather than selecting every tenth filter. 4.3.3 Records to Be Kept in a QA/QC System Records include: • Sample logbook • Chain-of-custody record 4.3.4 Field Monitoring Procedures—Air Sample Collection of 10% duplicates as provided by specifications are not to be confused with the 10% duplication used for QA in the NIOSH 7400 method. The 10% duplicates provided by specifications are for QC interlaboratory determination of reliability. These duplicates are collected in the field using simultaneous collection devices or analysis preparatory techniques. Running two pumps on one individual is feasible for personal air sampling. Running a Y shunt to two separate collection cassettes may be the technique used for area monitoring simultaneous collection. This method may also be feasible for personnel monitoring. When neither type of collection alternative is feasible, duplication of prepared slides through duplicate filter media mounting is acceptable. The rationale and techniques for all prospective alternatives must be provided in the QA/QC document. Caution: Field blanks must indeed be field blanks, not randomly prepared laboratory blanks. The purpose of field blanks is to access ambient air particulates hypothetically unassociated with abatement activities, but existing in the same general geographic location. Thus, field blanks must be filter-loaded cassettes that are open faced and stored outside the asbestos control area in an associated support zone. Occasionally, hygienists carry the field blanks in their pockets. This practice, if employed, must be documented, with associated persuasive rationale. 4.3.5 Calibration All calibration techniques and schedules must be provided. Calibration of air-sampling devices may be accomplished using a primary standard (such as a bubble burette) or using a precision rotameter calibrated against a primary standard. The bubble gauge installed on the front vertical face of personal air-sampling pumps is not a reliable or precise calibration tool. Calibration must be done using dial settings versus primary standard timings. Rotameters offer an advantage in that their portability makes it possible to calibrate cassettes with the associated vacuum pump-generated airstream (or train) at the worksite. Precision rotameters, while preferred, can be supplemented with standard rotameters. Techniques for rotameter use and calibration must be sequentially and clearly defined. The use of long-gauge range, 0–20 l/min, rotameters in the measure of personal air-sampling pumps with expected 2.5 l/min is prohibited due to lack of precision. Short-gauge range, 0–5 l/min rotameters, are allowed for use in the calibration of personal air sampling pumps. Example calibration curves and associated calculations must be provided. © 2001 CRC Press LLC
Slide 116: Calibration of Phase Contrast Microscopy (PCM) microscopes used on-site must be completely defined. All NVLAP and American Conference Governmental Industry Hygienists (ACGIH) calibration procedures are enforceable for on-site activities. While not generally defined as a calibration technique, cleanliness and relative stability of the PCM microscopic location must be addressed. Sample calibration checklists used daily and weekly must be provided. 4.3.6 Negative Air Pressure When negative air pressure is used in gross containment areas, monitoring criteria must be provided. Specifications should require continued real-time instrument monitoring independent of the HEPA vacuum system monitors. Monitors must be located outside the containment area and removed from the effluent HEPA vacuum airstream. Appropriate monitoring checklists and sample direct readout tapes must be provided. The readout tapes and associated calculations, if needed, can either be generically presented or be samples from previous monitoring efforts. 4.3.7 Compressor In the event that compressed air is used on-site, certification of Grade D breathing air must be provided. If a filter bank is used in conjunction with an oil-lubricated compressor, monitoring of the filter bank is required. This monitoring includes carbon monoxide, temperature, oil breakthrough, and air pressure criteria. In addition to audible alarms and escape air, visual monitoring of the compressor filter bank status is necessary. Provide sample monitoring check sheets. Certain specifications call for the use of colorimetric tubes to certify continued Grade D breathing air supply. Provide sample monitoring check sheets that clearly indicate sampling intervals. 4.3.8 Recordkeeping and Sample Storage Recordkeeping priorities and samples of format used must be provided. Records include documentation of air sampling and air sample analysis, bulk sampling and bulk sample analysis, and negative air pressure maintenance. Personnel records include résumés, certifications, medical surveillance, and training. Environmental records detail work sequencing and ambient conditions. All specified documents must be accessible and maintained as per specifications. Sample storage and accessibility must be discussed. The following equipment and documentation lists are examples of those that should be appraised for asbestos bulk sampling. Other laboratory protocols will require similar lists. Laboratory Procedures • • • • • • • • Logbook Calibration of refractive index oils Daily microscope alignment Daily microscope calibration check Daily microscope contamination check Equipment maintenance Equipment calibration Personnel records, including hierarchy, training, certification, and job descriptions © 2001 CRC Press LLC
Slide 117: • • • • Monthly records of each analyst QA and QC results for their work Proficiency results (PAT) Precision and accuracy ratings, including explanation of rating protocols QA Logbook • • • • • • • • • Samples Results Discrepancies Analysis repeats (minimum 10%) Intralaboratory analysis of proficiency samples Intralaboratory analysis of duplicates and replicates Blank analysis Summary of results from each analyst Summary of results for the laboratory QC Logbook • • • • • • • • • Deficiency corrections Samples Results Discrepancies Frequency of duplicate/replicate analysis per total samples Interlaboratory analysis of proficiency samples Timing of QC analysis Same day, next shift, next day Monthly proficiency samples, WULAP samples in-house or past EPA asbestos bulk sample analysis, QA program samples, blanks, and contamination samples Interlaboratory Analyses (summary of results for the laboratory) • • • • • • • • • • Outliers Interlaboratory analysis schedules Time, including expected turnaround time Labs participating Contamination testing and control logbook Lab data sheet/notebook Analysis report sheet QA manual revision documentation Training procedures for staff Analysis error correction correspondence 4.4 SAMPLING AND ANALYTICAL ERRORS When an employee’s personal exposure or the area exposure is sampled and the results analyzed, the measured exposure will rarely be the same as the true exposure. This variation is due to sampling and analytical errors or SAEs. The total error depends on the combined effects of the contributing errors inherent in sampling, analysis, and pump flow. © 2001 CRC Press LLC
Slide 118: Error factors determined by statistical methods shall be incorporated into the sample results to obtain: • The lowest value that the true exposure could be (with a given degree of confidence) • The highest value the true exposure could be (also with some degree of confidence) The lower value is called the lower confidence limit (LCL), and the upper value is the UCL. These confidence limits are one sided, since the only concern is with being confident that the true exposure is on one side of the Permissible Exposure Limit (PEL). 4.4.1 Determining SAEs SAEs that provide a 95% confidence limit have been developed and are listed on the OSHA-91B report form (most current SAEs). If there is no SAE listed in the OSHA-91B for a specific substance, call the laboratory. If using detector tubes or direct-reading instruments, use the SAEs provided by the manufacturer. 4.4.2 Environmental Variables Environmental variables generally far exceed SAE. Samples taken on a given day are used by OSHA to determine compliance with PELs. However, where samples are taken over a period of time (as is the practice of some employers), the industrial hygienist should review the long-term pattern and compare it with the results. When OSHA’s samples fit the long-term pattern, it helps to support the compliance determination. When OSHA’s results differ substantially from the historical pattern, the industrial hygienist should investigate the cause of this difference and perhaps conduct additional sampling. 4.4.3 Confidence Limits One-sided confidence limits can be used by OSHA to classify the measured exposure into the following categories. 95% Confident That the Employer Is in Compliance • Measured exposure results do not exceed the PEL. • UCL of that exposure does not exceed the PEL. 95% Confident That the Employer Is NOT in Compliance • Measured exposure results do exceed the PEL. • LCL of that exposure does exceed the PEL. 95% Confident That the Employer Is in Compliance • Measured exposure results do not exceed the PEL. • UCL of that exposure does exceed the PEL. Possible Overexposure © 2001 CRC Press LLC
Slide 119: NOT 95% Confident That the Employer Is NOT in Compliance Possible Overexposure • Measured exposure results do exceed the PEL. • LCL of that exposure does not exceed the PEL. A violation is not established if the measured exposure is in the “possible overexposure’’ region. It should be noted that the closer the LCL comes to exceeding the PEL, the more probable it becomes that the employer is in noncompliance. If measured results are in this region, the industrial hygienist should consider further sampling, taking into consideration the seriousness of the hazard, pending citations, and how close the LCL is to exceeding the PEL. If further sampling is not conducted, or if additional measured exposures still fall into the “possible overexposure’’ region, the industrial hygienist should carefully explain to the employer and employee that the exposed employee(s) may be overexposed, but that there were insufficient data to document noncompliance. The employer should be encouraged to voluntarily reduce the exposure and/or to conduct further sampling to assure that exposures are not in excess of the standard. 4.5 SAMPLING METHODS The LCL and UCL are calculated differently depending on the type of sampling method used. Sampling methods can be classified into one of three categories: 4.5.1 Full-Period, Continuous Single Sampling Full-period, continuous single sampling is defined as sampling over the entire sample period with only one sample. The sampling may be for a full-shift sample or for a short period ceiling determination. 4.5.2 Full-Period, Consecutive Sampling Full-period, consecutive sampling is defined as sampling using multiple consecutive samples of equal or unequal time duration that, if combined, equal the total duration of the sample period. An example would be taking four 2-hour charcoal tube samples. There are several advantages to this type of sampling. If a single sample is lost during the sampling period due to pump failure, gross contamination, etc., at least some data will have been collected to evaluate the exposure. The use of multiple samples will result in slightly lower SAE. The collection of several samples leads to conclusions concerning the manner in which differing segments of the workday affect overall exposure. 4.5.3 Grab Sampling Grab sampling is defined as collecting a number of short-term samples at various times during the sample period that, when combined, provide an estimate of exposure over the total period. Common examples include the use of detector tubes or direct-reading instrumentation (with intermittent readings). © 2001 CRC Press LLC
Slide 120: 4.6 CALCULATIONS If the initial and final calibration flow rates are different, a volume calculated using the highest flow rate should be reported to the laboratory. If compliance is not established using the lowest flow rate, further sampling should be considered. Sampling is generally conducted at approximately the same temperature and barometric pressure as calibration, in which case no correction for temperature and pressure is required, and the sample volume reported to the laboratory is the volume actually measured. Where sampling is conducted at a substantially different temperature or pressure than calibration, an adjustment to the measured air volume may be required depending on sampling pump used, in order to obtain the actual air volume sampled. The actual volume of air sampled at the sampling site is reported and used in all calculations. For particulates the laboratory reports milligrams per cubic meter of contaminant using the actual volume of air collected at the sampling site. This value can be compared directly to OSHA Toxic and Hazardous Substances Standards (e.g., 29 CFR 1910.1000). The laboratory normally does not measure concentrations of gases and vapors directly in parts per million. Rather, most analytical techniques determine the total weight of contaminant in a collection medium. Using the air volume provided by the industrial hygienist, the lab calculates the concentration in milligrams per cubic meter and converts this to parts per million at 25°C and 760 mmHg. This result is to be compared with the PEL without adjustment for temperature and pressure at the sampling site. ppm(NTP) where • 24.45 • Mwt • NTP molar volume at 25°C (298 K) and 760 mmHg molecular weight normal temperature and pressure at 25°C and 760 mmHg mg/m3(24.45)/(Mwt) If it is necessary to know the actual concentration in parts per million at the sampling site, it can be derived from the laboratory results reported by using the following equation: ppm(PT) where • P sampling site pressure (mmHg) • T sampling site temperature (K) • 298 temperature in K Since ppm(NTP) mg/m3 (24.45)/(Mwt) ppm(PT) mg/m3 24.45/Mwt 760/P T/298 ppm(NTP) (760)/(P) (T)/(298) Note: When a laboratory result is reported as milligrams per cubic meter contaminant, concentrations expressed as parts per million (PT) cannot be compared directly to the standards table without converting to NTP. Note: Barometric pressure can be obtained by calling the local weather station or airport and requesting the unadjusted barometric pressure. If these sources are not available, then a rule of thumb is for every 1000 ft increase in elevation, the barometric pressure decreases by 1 in.Hg. © 2001 CRC Press LLC
Slide 121: 4.6.1 Calculation Method for a Full-Period, Continuous Single Sample Obtain the full-period sampling result (value X), the PEL, and the SAE. The SAE can be obtained from the OSHA Chemical Information Manual. Divide X by the PEL to determine Y, the standardized concentration, that is, Y X/PEL. Compute the UCL (95%) as follows: UCL(95%) Compute the LCL (95%) as follows: LCL(95%) Y SAE Y – SAE Classify the exposure according to the following classification system: • If the UCL • If the LCL • If the LCL 1.0, a violation does not exist. 1.0 and the UCL 1, classify as possible overexposure. 1.0, a violation exists. 4.6.2 Sample Calculation for a Full-Period, Continuous Single Sample A single fiberglass filter and personal pump were used to sample for carbaryl for a 7-h period. The industrial hygienist was able to document that the exposure during the remaining unsampled 0.5 h of the 8-h shift would equal the exposure measured during the 7-h period. The laboratory reported 6.07 mg/m3. The SAE for this method is 0.23. The PEL is 5.0 mg/m3. Step 1. Calculate the standardized concentration. Y 6.07/5.0 1.21 Step 2. Calculate confidence limits. LCL 1.21 – 0.23 0.98 Since the LCL does not exceed 1.0, noncompliance is not established. The UCL is then calculated: UCL 1.21 0.23 1.44 Step 3. Classify the exposure. Since the LCL 1.0 and the UCL 1.0, classify as possible overexposure. 4.6.3 Calculation Method for a Full-Period Consecutive Sampling The use of multiple consecutive samples will result in slightly lower SAEs than the use of one continuous sample because the inherent errors tend to partially cancel each other. The mathematical calculations, however, are somewhat more complicated. If preferred, the industrial hygienist may first determine if compliance or noncompliance can be established using the calculation method noted for a full-period, continuous, single-sample measurement. If results fall into the “possible overexposure’’ region using this method, a more exact calculation should be performed as follows. © 2001 CRC Press LLC
Slide 122: Compile X(1), X(2) . . . , X(n), and the n consecutive concentrations on one workshift. Compile their time durations, T(1), T(2), . . . , T(n). Compile the SAE. Compute the TWA exposure. Divide the TWA exposure by the PEL to find Y, the standardized average (TWA/PEL). Compute the UCL (95%) as follows: UCL (95%) Y SAE (Equation E). Compute the LCL (95%) as follows: LCL (95%) Y SAE (Equation F). Classify the exposure according to the following classification system: • If the UCL • If the LCL • If the LCL 1.0, a violation does not exist. 1.0, and the UCL 1, classify as possible overexposure. 1.0, a violation exists. When the LCL 1.0 and the UCL 1.0, the results are in the “possible overexposure’’ region, and the industrial hygienist must analyze the data using the more exact calculation for full-period consecutive sampling, as follows: LCL Y SAE(T12X12 T22X22 . . . PEL(T1 T2 Tn) Tn2Xn2)1/2 4.6.4 Sample Calculation for Full-Period Consecutive Sampling Two consecutive samples were taken for carbaryl instead of one continuous sample, and the following results were obtained: Sample Sampling rate (L/min) Time (min) Volume (L) Weight (mg) Concentration (mg/m3) A 2.0 240.0 480.0 3.005 6.26 B 2.0 210.0 420.0 2.457 5.85 The SAE for carbaryl is 0.23. Step 1. Calculate the UCL and the LCL from the sampling and analytical results: TWA (6.26 mg/m3 240 min (5.85 mg/m3) 210 min 450 min 6.07 mg/m3 Y 6.07 mg/m3/PEL 6.07/5.0 1.21 Assuming a continuous sample: LCL 1.21 – 0.23 0.98 UCL 1.21 0.23 1.44 Step 2. Since the LCL 1.0 and the UCL 1.0, the results are in the possible overexposure region, and the industrial hygienist must analyze the data using a more exact calculation for full-period consecutive sampling. If the LCL 1.0, a violation is established. © 2001 CRC Press LLC
Slide 123: 4.7 GRAB SAMPLING If a series of grab samples (e.g., detector tubes) is used to determine compliance with either an 8-h TWA limit or a ceiling limit, consult with an industrial hygienist (ARA) regarding sampling strategy and the necessary statistical treatment of the results obtained. 4.8 SAES—EXPOSURE TO CHEMICAL MIXTURES Often an employee is simultaneously exposed to a variety of chemical substances in the workplace. Synergistic toxic effects on a target organ are common for such exposures in many construction and manufacturing processes. This type of exposure can also occur when impurities are present in single chemical operations. New PELs for mixtures, such as the recent welding fume standard (5 mg/m3), addresses the complex problem of synergistic exposures and their health effects. In addition 29 CFR 1910.1000 contains a computational approach to assess exposure to a mixture. This calculation should be used when components in the mixture pose a synergistic threat to worker health. Whether using a single standard or the mixture calculation, the SAE of the individual constituents must be considered before arriving at a final compliance decision. These SAEs can be pooled and weighted to give a control limit for the synergistic mixture. To illustrate this control limit, the following example using the mixture calculation is shown. The mixture calculation is expressed as: Em where • Em equivalent exposure for a mixture (Em should be • C concentration of a particular substance • L PEL 1 for compliance) (C1/L1 C2/L2) . . . Cn/Ln) For example, to calculate exposure to three different, but synergistic substances: Material Substance 1 Substance 2 Substance 3 8-h exposure 500 80 70 8-h TWA PEL (ppm) 1000 200 200 SAE 0.089 0.11 0.18 Using Equation I: Em 500/1000 80/200 70/200 1.25 Since Em 1, an overexposure appears to have occurred; however, the SAE for each substance also needs to be considered: • Exposure ratio (for each substance): Yn Cn/Ln • Ratio to total exposure: R1 Y1/Em1 . . . Rn Yn/Em • The SAEs (95% confidence) of the substance comprising the mixture can be pooled by: (RSt2) [(R12) (SAE12) (R22) (SAE22) . . . (Rn2) (SAEn2)] © 2001 CRC Press LLC
Slide 124: • The mixture control limit (CL) is equivalent to 1 RSt. — If Em CL1, then an overexposure has not been established at the 95% confidence level; further sampling may be necessary. —If E m 1 and E m CL1, then an overexposure has occurred (95% confidence). • Using the mixture data above: Y1 Y1 R1 500/1000 0.5 Y1/Em 0.4 Y2 Y2 R2 80/200 0.4 0.32 Y3 Y3 R3 70/200 0.35 0.28 • • • • (RSt)2 (0.42)(0.0892) (0.322)(0.112) RSt [(RSt)2)](1/2) 0.071 CL 1 RSt 1.071 Em 1.25 (0.282)(0.182) Therefore Em CL and an overexposure has occurred within 95% confidence limits. This calculation is also used when considering a standard such as the one for total welding fumes. © 2001 CRC Press LLC
Slide 125: CHAPTER 5 Chemical Risk Assessment Real-world examples portray the decision logic needed to conduct chemical sampling when assessing risk. This chapter includes a troubleshooting section/checklist to assist samplers in either choosing a consultant or appraising in-house sampling methodology. Chemical risk assessment is a twofold process. One part occurs off-site as known chemical information is assessed and calculations based on accepted formulas are done. The EPA baseline risk assessments (BLRAs), screening assessments, and remedial investigation studies rely on a body of knowledge accumulated over the last 20 years. Decisions about supportive air monitoring and actual on-site monitoring required during sampling events should also be made at this time. The second stage is the actual accumulation of data during which workers must be protected against airborne hazards, including those resulting from their sampling efforts, including disturbance of the on-site medium (soil, water). Decision-making concerning personal protection and engineering controls may require air monitoring of personnel, area of influence, and the site perimeter. In order to understand the context under which air monitoring protocols are developed, an understanding of chemical risk assessment for these sites is necessary. Keep in mind that the term site is an all inclusive one for this section and may include active industrial and/or construction sites. 5.1 BASELINE RISK ASSESSMENT Monitoring to determine chemical risk may lead to a BLRA consistent with U.S. EPA Comprehensive Environmental Resource Conservation Liability Act (CERCLA) guidance documents that address: • Potentially contaminated groundwater • Surface water runoff, sediment, and river area • Soils The results of the BLRA may be used to • Prioritize the need for site remediation or abatement activities. • Provide the basis for quantification of remedial objectives. • Assist in planning objectives to minimize risk. ©2001 CRC Press LLC
Slide 126: 5.2 CONCEPTUAL SITE MODEL The first step in developing a BLRA is to provide a conceptual site model that has been developed to evaluate source areas, migration pathways, and possible exposure points for receptors. Migration pathways are potential conduits for contaminants to reach on-site and off-site receptors. This model is then used to determine the medium that needs to be sampled. 5.2.1 Source Areas The source areas are limited to the areas delineated by the model. Source areas such as soil areas, bodies of water, and air emissions are areas for concern. Soils in particular may be primary and secondary source areas—primary as particulates that may lead to ingestion or dermal hazard, and secondary as soils that may be dispersed in the airstream through on-site activities. 5.2.2 Possible Receptors In accordance with the EPA standard default exposure factors (SDEFs) guidance, construction worker, commercial/industrial, and recreational populations are considered possible receptors in the human health evaluation. Sampling efforts to quantify and qualify the potential exposure pathways will focus on predictive sampling of the medium of concern, including surface soil, subsurface soil, groundwater, and air. The source areas are defined as the current industrial use soil contamination. 5.3 CHEMICALS OF POTENTIAL CONCERN Groundwater and soil analytical data from samples collected from the site area are evaluated for preliminary determination of chemicals of potential concern (COPCs). Samples are from known hot spots as a worst-case scenario for soils and are evaluated using log-normal distribution, Kriging, or Monte Carlo analysis. Ground- and surface-water samples are collected (20 samples per location) and are evaluated using normal distribution assumptions. The frequency of detection of chemicals in each medium is calculated as the number of total detections out of the total number of analytical samples for each medium. Duplicate sample data will not considered in this calculation. The positively identified chemicals for each medium are reviewed to identify chemicals that could potentially result in adverse health effects in humans or in adverse environmental effects. Detected concentrations are compared to potential applicable or relevant and appropriate requirements (ARARs). ARARs include Safe Drinking Water Act (SDWA) maximum contaminant levels (MCLs), lifetime health advisory levels (HALs), and U.S. EPA Region VII preliminary remediation goals (PRGs). If detected concentrations are significantly below health-based ARARs or if compounds are known to be nontoxic, they are eliminated from further consideration. © 2001 CRC Press LLC
Slide 127: 5.4 HUMAN HEALTH BLRA CRITERIA To understand the rationale for selecting sample sites, the sampler must have a basic understanding of risk assessment criteria. The following components of a risk assessment are normally part of all risk assessment discussions—even if those discussions are ultimately negative declarations—“we do not have to worry about that.’’ 5.5 TOXICITY ASSESSMENT The toxicity assessment weighs available evidence that COPCs may cause adverse health effects in exposed humans or other biota. The assessment estimates the extent of potential chemical exposure and the increased likelihood and/or severity of adverse effects. The toxicity assessment at the site location is accomplished in two steps: 1. Chemical hazard identification determines whether potential chemical exposure causes an increased incidence or severity of an adverse health or environmental effect. Toxicological data for COPCs are reviewed, and toxicological profiles are prepared for the COPCs. 2. The dose-response evaluation consists of quantitatively evaluating the toxicity information. Then the relationship between the chemical dose and the resultant incidence/severity of adverse health or environmental effects are reviewed. The risk characterization portion of the BLRA estimates the likelihood of adverse effects occurring under the exposure scenarios. For the chemicals identified (except lead) the toxicity values have been derived by the U.S. EPA and are summarized in the Integrated Risk Information System (IRIS) database. The EPA has not developed a reference dose (RfD) or carcinogenic potency slope factor (SF) for elemental lead. The EPA considers lead a special case because lead is ubiquitous in all media; therefore, human exposure comes from multiple sources. Thus most people would exceed an RfD level under “background’’ conditions. The EPA Office of Solid Waste and Emergency Response (OSWER) has released a directive on BLRA and cleanup of residential soil lead. This directive recommends that soil lead levels less than 400 ppm are considered safe for residential use. The EPA action level (SDWA) for lead in drinking water is 15 g/l. An RfD, 1 10 7 mg/kg/day, has been provided for tetraethyl lead, formerly a common additive for gasolines in the U.S. The current accepted site usage levels for lead are evaluated in concert with the surrounding area soil levels. For noncarcinogens, an RfD is established by the EPA as a result of hazard identification and dose-response evaluation. The RfD is an estimate of an exposure level judged likely to be without an appreciable risk of adverse health effects over a specified time of exposure. A critical study (or studies) in which a dose causing an adverse effect is identified at a lower level of exposure as either having no effect or minimal effect—yields the RfD. Chronic RfDs reflect a level of exposure that would not result in adverse effects when experienced for 7 years to a lifetime (Baseline Risk Assessment Guidance for Superfund [RAGS] Part A). If the RfD is expressed as an administered dose, dermal toxicity values are derived by adjusting the oral toxicity value (i.e., multiplying by a chemical absorption factor). The noncarcinogenic effects potential is evaluated by comparing the chemical intake with an RfD. This ratio is referred to as a hazard quotient (HQ). The HQ assumes that © 2001 CRC Press LLC
Slide 128: below a certain level of exposure, even sensitive populations will not experience adverse effects. Based on this assumption, if exposure is equivalent to or less than the RfD and the HQ is 1.0 or less, a hazard is not likely to exist. If the HQ exceeds 1.0, a hazard may exist. For carcinogens a cancer SF and a weight-of-evidence classification are the toxicity values used in the characterization of potential human carcinogenic risks. The relationship relating exposure level to the probability of developing cancer (i.e., the incidence) is expressed as a cancer SF. The SF is a plausible upper-bound estimate of the probability of developing cancer per unit intake of a chemical over a lifetime. SFs are expressed as (mg/kg-day) 1. If the SF is expressed as an administered dose, a dermal toxicity value is derived by adjusting the oral toxicity value (i.e., dividing by the chemical absorption factor). The potential for carcinogenic effects is estimated by multiplying a chemical’s SF by the lifetime average daily chemical intake. Exposure to carcinogens resulting in an increased carcinogenic risk of 1 10 6 or greater may be cause for potential concern and may indicate the need for remedial action. The risk of developing cancer as a result of exposure to carcinogens can also be expressed as a unit risk. This toxicity value represents a risk per unit concentration in the particular medium contacted. Unit risks reflect risks resulting from continuous lifetime exposures. Unit risks are expressed as ( g/m3) 1 for inhalation exposures or ( g/l) 1 for oral exposures. A unit risk in the range of 1 10 4 to 1 10 6 implies that an individual has between a 1 in 10,000 and a 1 in 1,000,000 chance of developing cancer in excess of a background incidence if exposed to 1 g/m3 air or 1 g/l water of a carcinogenic chemical for a lifetime. The carcinogenic potential of a chemical is classified into one of the following groups according to the weight of evidence from epidemiological and animal studies: • A—human carcinogen • B1—probable human carcinogen (limited evidence of carcinogenicity in humans) • B2—probable human carcinogen (sufficient evidence in animals with inadequate evidence in humans) • C—possible human carcinogen (limited evidence of carcinogenicity in animals or lack of human data) • D—not classifiable as a human carcinogen • E—evidence of noncarcinogenicity in humans 5.6 TOXICOLOGICAL PROFILES The Agency for Toxic Substances and Disease Registry (ATSDR) data and IRIS information are used to prepare toxicological profiles for COPCs. The toxicological profiles will include specific toxicological information (e.g., toxicological effects, target organs, critical effect). 5.7 UNCERTAINTIES RELATED TO TOXICITY INFORMATION The RfDs established for COPCs are a major source of uncertainty in a BLRA. The RfD is the estimate of daily exposure likely to be without an appreciable risk of deleterious effects during a lifetime. The RfD is derived by the application of uncertainty factors to selected exposure levels identified in animal or human studies. Identified exposure levels are divided by these uncertainty factors to assure that the RfD will not be overestimated. © 2001 CRC Press LLC
Slide 129: For example, an uncertainty factor of 10 is used to account for variations in human sensitivity when using data from valid human studies involving long-term exposure of average, healthy subjects. Additional uncertainty factors of 10 are applied to account for uncertainties in extrapolating from observation of toxicity in animals to predicted toxicity in humans, to account for uncertainties in identifying threshold dose from experimental data, and to account for uncertainties in extrapolating from subchronic to chronic studies. Any additional uncertainty factor or modifying factor ranging from 0 to 10 may be applied to reflect professional assessment of other uncertainties that may exist in the toxicity database for a specific compound. Considerable uncertainties are involved in identifying whether or not a compound is a likely potential human carcinogen and at what level of exposure an increased risk of cancer may exist. Uncertainties in quantifying the exposure level that may result in elevated carcinogenic risk for specific compounds are compensated for by using the 95% UCL of the estimated slope. This slope refers to the line that relates chemical exposure to the probability of developing cancer—thus the term slope factor for carcinogens. Using the 95% UCL is a statistical path to assure that the actual SF is highly unlikely to be greater than the SF listed for that chemical. These dose-response assumptions provide an upper, but plausible, estimate of the limit of risk when the SF is used to estimate risk associated with an estimated level of exposure. 5.8 POTENTIALLY EXPOSED POPULATIONS For the future land-use scenario the assumption is that the site property will remain a site. The population to be considered includes on-site workers, site visitors, and possible future construction workers. The population may be exposed to surface soil, subsurface soil, and groundwater through inhalation, ingestion, and dermal contact. The monitoring results of the well survey efforts are used to determine completed exposure pathways. The site does not have on-site residential or adjacent residential property; therefore, the soil exposure pathway is not applicable (i.e., complete) for on-site or adjacent sites. Recreational receptors to be evaluated will include site trespassers and users of the site. 5.8.1 Exposure Pathways The exposure pathway is the course a chemical takes from the source to the exposed individual. The exposure pathway is characterized by the source (the contaminated medium), the mechanism of release, a retention or transport medium, a point of potential human contact with a contaminated medium, and an exposure route at the point of contact (i.e., ingestion). An exposure pathway is complete only when each of these elements is present. Air monitoring may be used to supplement theoretical calculations of air dispersion pathways. 5.8.2 Sources Surface soil and subsurface hydrogeological formations (i.e., soil/groundwater system) that have been affected by the site’s former usage are the source areas that come under consideration. © 2001 CRC Press LLC
Slide 130: 5.9 ENVIRONMENTAL FATE AND TRANSPORT OF COPCs The inorganic contaminants identified at the site may not be generally considered mobile in the soil/groundwater system. Mobility is affected by soil pH and groundwater for aqueous transport. Factors influencing dust generation and movement from the soil surfaces to the air migration pathway must also be considered. Inorganic contaminant mobility through storm water runoff and surface water transport are evaluated. Existing site conditions are evaluated to estimate the migration of contaminants to subsurface soil, groundwater, and surface water, and air. 5.10 EXPOSURE POINTS AND EXPOSURE ROUTES Only complete exposure pathways involving current or future contact with contaminated media are cause for concern. Exposure pathways, in that the potentially exposed population is not likely to experience significant contaminated medium contact or the environmental medium contacted is not significantly contaminated, will not be considered. Therefore, before determining that the pathways are complete and that the possible receptors are likely to be exposed at significant levels, site-specific information is gathered. This information will also be used to develop site-specific exposure parameters. An interim BLRA deliverable is prepared to propose the exposure scenarios that are used in the final BLRA. 5.11 COMPLETE EXPOSURE PATHWAYS EVALUATED A well survey is conducted to determine if any down-gradient domestic wells at the site may be affected. Based on the proximity of the wells, their depth, construction, and use, the potential for these wells to be affected by the site are determined. Irrigation wells, if within the site’s vicinity, are a potential exposure pathway vector to the fields that are irrigated. For the industrial exposure scenario, on-site workers and site visitors are considered for exposure to contamination through surface soil, subsurface soil, and air. The recreational exposure scenarios are considered for site trespassers and visitors to the site. 5.12 ECOLOGICAL RISK ASSESSMENT Pathways for terrestrial and aquatic environmental receptors regarding exposure to subsurface soil, surface soil, sediment, surface water, and air are considered in the ecological component of the risk assessment. The ecological component of the BLRA characterization includes the following: • Identification of habitats and predominant species occurring at the site including the river areas • Selection of representative species that may have the greatest exposure based on feeding habits, habitat usage, and exposure duration (Receptors of concern will also be evaluated based on available published eco-toxicological data.) • Verification that contaminants of potential ecological concern are limited to heavy metals © 2001 CRC Press LLC
Slide 131: • Research into toxicological reference values in published material (Ambient water quality criteria [AWQC] are used for contaminants.) • Evaluation of environmental data to adequately estimate existing and potential future ecological risks • Development of a sampling and analysis plan (SAP) for data collection to evaluate ecological exposure • Determination whether background data are required or if other information such as surface water hardness is necessary to evaluate toxicity • Quantification of exposure by estimating the magnitude and rate of exposure for receptors of concern. (This quantification will include evaluation of contaminant concentrations, bioavailability, bioaccumulation, bioconcentration, and biomagnification potential; feeding rates; habitat usage; and food chain considerations.) • Review of the results of the toxicity and exposure assessments • Comparisons of exposure concentrations to appropriate toxicological reference values to complete a risk characterization (This characterization will include an evaluation of the spatial distribution of contamination with regard to ecological receptors.) Decisions on whether an ecological impact exists are based on this risk characterization. Sampling to determine contaminant exposure potential then follows the same criteria as for the human health risk assessment, except that sampling routines may be specialized to deal with species-specific exposures. An example would be the exposure of burrowing animals to soils through ingestion, inhalation, and dermal contact. 5.13 DATA EVALUATION AND DATA GAPS Existing data for concentrations of contaminants in the medium of concern—surface soil, subsurface soil, groundwater, and air—are evaluated. This evaluation will determine if data are adequate to estimate exposure point concentrations and to evaluate contaminant migration and toxicity. Existing data will also be evaluated to determine if data are of adequate quality for use in a risk assessment according to the methods specified in the U.S. EPA guidance, Data Usability in Risk Assessments. If additional environmental data are necessary to complete the BLRA, an SAP is developed. In addition to chemical data, collection of water quality data (i.e., hardness) may be specified in the SAP because the toxicity and mobility of metals in surface water is hardness dependent. At this time an evaluation of existing data indicates that on-site groundwater data are available. Current groundwater data and new empirical data are evaluated for background and down-gradient information. The arithmetic means and 95% UCLs of the mean are calculated for COPCs. For the groundwater pathways a well survey is conducted within 1 mile of the site to verify the locations and uses of all wells. If recontouring of the soil surface has occurred to direct storm water runoff toward collection points, additional surface soil samples (0–2 in.) may be necessary for the analysis of COPCs in the soil ingestion and air pathways. Data collection points are designed to identify hot spots and to calculate average concentrations over the entire site and in the areas of concern. Soil pH must also be measured because soil pH influences metals transport. Surface water data for up-gradient and down-gradient points and sample collection points for this data are identified. No surface water or sediment data from on-site © 2001 CRC Press LLC
Slide 132: drainages, or drainage pathways from the site, may be available to provide information on the extent of contaminant migration. Sediment data from the surface water pathway provide information on whether the rivers or standing bodies of water subject to runoff are another source of contamination to other surface waters. Collect surface water and sediment samples from these areas. The level of generation of dust at the site is required information. This information may be collected via real-time particulate measurements and/or by collecting samples for laboratory analysis. The level of dust generation is assumed to vary significantly with time and climatic data. The collection of dust generation data is planned carefully so that dust generation is neither underestimated or overestimated. 5.14 UNCERTAINTIES Uncertainties may relate to several factors, such as toxicity information or exposure assessments. 5.14.1 Uncertainties Related to Toxicity Information The RfDs for COPCs are a major source of uncertainty in a BLRA. A chronic RfD is an estimate of the daily exposure unlikely to present an appreciable risk of deleterious effects during a lifetime. Uncertainty factors are applied to selected exposure levels identified in animal or human studies to derive the RfD. To avoid overestimating the RfD, identified exposure levels are divided by these uncertainty factors. An uncertainty factor of 10 is used to account for variations in human sensitivity when using data from valid human studies involving long-term exposure of average, healthy subjects. When extrapolating from observations of toxicity in animals to predicted toxicity in humans, additional uncertainty factors of 10 are applied. Uncertainties are also present when identifying whether a compound is a likely human carcinogen and at what level of exposure an increased risk of cancer may exist. Uncertainties in quantifying the exposure levels that may result in elevated carcinogenic risk for specific compounds are corrected for by using the 95% UCL of the slope relating exposure to the probability of developing cancer. The actual slope may be greater, but is unlikely to be greater. The lack of an RfD and a cancer SF for lead will introduce uncertainty into the BLRA if lead is a COPC. 5.14.2 Uncertainties in the Exposure Assessment Uncertainties in the exposure assessment are introduced in estimating the concentrations to which receptors may be exposed to in the future and in identifying exposed populations. The future land use at the facility and prediction of the future surrounding use add uncertainty to this assessment. The exposure scenarios selected are developed to model the highest reasonable potential exposures to site contaminants. These estimates are unlikely to underestimate future potential risk. Estimates of exposure frequency and duration are also uncertain. Reasonable levels were selected that are not likely to underestimate the risk associated with site-related activities. • Uncertainty is present in exposure point concentration estimations. • All data for metals in groundwater are based on unfiltered groundwater samples. © 2001 CRC Press LLC
Slide 133: 5.15 RISK CHARACTERIZATION Based on intake calculations and the identification of complete exposure pathways, an overall site characterization and a risk characterization are completed. This will include the following: • Written justification for the assumptions used to calculate human dose or intake • Characterization of carcinogenic risk using EPA-established carcinogenic SFs • Estimation of carcinogenic risk expressed as the incremental increase in the probability of an individual developing cancer over a lifetime (incremental lifetime cancer risks [ILCRs]) • Summation of ILCRs for individual COPCs across pathways and within receptor exposure scenarios (e.g., on-site worker exposed to groundwater) • Estimation of potential adverse health effects from exposure to systemic toxicants via comparing an exposure intake to a standard RfD (This ratio is the HQ.) • Estimation of HQs for each COPC for which toxicity values are available • Assumption of individual COPC HQ additivity applied to chemicals that induce the same effect on the same target organ The summation of HQs is judged to form valid upper-bound hazard indices. These summations are considered only when chemicals within the mixture exhibit “dilution type interaction’’ (Science Advisory Board Review of the OSWER draft RAGS, Human Health Evaluation Manual [HHEM], EPA-SAB-EHC-93-007). These chemicals within a mixture must have interactions that are independent mechanisms; synergistic and/or antagonistic interactions invalidate the summation of HQs. Consider indirect exposures (e.g., through the food chain) when receptors have been identified as currently present on-site or potentially identified given reuse options. Grazing scenarios are to be considered both as indirect exposures to humans and with the ecological assessment. Consider exposure pathways related to soil contamination in terms of dermal and inhalation of fugitive dust hazards. 5.16 HEADSPACE MONITORING—VOLATILES The PID is a quantitative instrument that measures the total concentration of various VOCs in the air. The PID may be used as an approach instrument to monitor for safe approach to the site’s hot spots and also for headspace analysis of any samples taken. When wells are drilled and/or soil borings are taken, the headspace in the borehole is monitored to assure safety to the drill crew. The PID measures in the parts per million range; therefore, sustained deflection of over 5 ppm for 1 min is a good indicator of volatile presence long before most volatile chemicals reach an explosive potential. PIDs are also used for ongoing monitoring of personnel exposures. If a detection of volatiles occurs, either detector tube or solvent tube sampling may be required to identify the exact volatile chemical constituency. 5.17 O2 /CGI The O2/CGI is an air-monitoring device designed to indicate the level of oxygen present and monitor for a flammable/explosive atmosphere. The CGI registers combustible gas © 2001 CRC Press LLC
Slide 134: or vapors in terms of their LEL, which is the lowest concentration at which a combustible gas may ignite (or explode) under normal atmospheric conditions. These instruments are required on all sites where volatiles may be expected to reach LEL levels and for all sampling requiring confined space entry. 5.18 INDUSTRIAL MONITORING—PROCESS SAFETY MANAGEMENT Sampling at industrial sites to determine chemical risk proceeds to determine employee exposure potential and ultimately chemical risk. The chemical risk assessment scenarios used by the EPA may or may not be applicable or relevant. In cases where exposure can be compared to OSHA PELs and STELs, calculation of risk may not be necessary. Screening with portable monitors (PIDs and O2/CGIs) or detector tubes can be used to evaluate the following: • • • • • Exposures to substances as to PELs in relatively dust-free atmospheres Intermittent processes using substances that do not have STELs Engineering controls Work practices Isolation of process A sufficient number of samples must be taken to obtain a representative estimate of exposure. Contaminant concentrations vary seasonally, with weather, with production levels, and in a single location or job class. When determining exposure levels, you may elect to turn off or remove sampling pumps before employees leave a potentially contaminated area (such as when they go to lunch or on a break). If you follow this OSHA-allowed protocol, you MUST document and be able to prove zero exposure during the time interval the monitor was turned off. 5.19 BULK SAMPLES Bulk samples are often required to assist the industrial hygienist in the proper analysis of field samples at industrial sites. Bulk samples can also be taken and analyzed to support any hazard communication inspections (i.e., Material Safety Data Sheet determinations). © 2001 CRC Press LLC
Slide 135: CHAPTER 6 Biological Risk Assessment Given that many of the indoor air problems (whether on remediation sites or elsewhere) are caused by biological contaminants and their decomposition products, Chapter 6 provides real-world examples of biological monitoring protocols. All sampling for biologicals must take into account surrounding environmental factors and building usage. Drawing a complete history and in some cases additional types of air sampling for other contaminants are required. In discussing sampling for biologicals we will also discuss the reasons for concern and control mechanisms that can be used. You must always remember that biologicals, unlike chemical contaminants, have the potential to reproduce and thus grow in numbers. Care must be taken to sample in a consistent fashion in as short a period as possible. Reproduction of biologicals also calls into question the relative viability of spores and bacterial colonies that are encysted. In cases where amplification is primarily bacterial, these colonies may inhibit spores from developing into vegetative structures. Consequently comparative levels for bacterial counts and mold colony forming units (CFUs) may be required, especially since spores in and of themselves can be problematic. Thus, the absence of visible mold growth may not be indicative of a clean environment. When molds are amplified to the extent that the building is increasingly hospitable to further mold growth, we may begin to see pathogenic colonies (that would not otherwise be present) taking hold in a building’s interior. All of us exhibit great concern when confronted with possible Stachybotrys atra (Stachy). Airstream movement does not readily spread Stachy, as the spores become less viable in dry airstream environments. However, in moisture-laden airstreams or within homes with other amplified mold colonies, Stachy may begin to flourish. In areas where bird or other animal droppings are prevalent, we begin to be concerned about histoplasmosis and coccidiomycosis. Histoplasma (Histo) is the more likely disease vector where other molds are flourishing, given that Histo is better able to survive in wetter environments. Keep in mind that the term wet is a relative one. Some of these molds do not need “wet’’ environments in the traditional sense to grow well; any condensation will do, even that caused by very slight temperature differences. The old way of thinking that fiberglass will not grow biologicals is also not correct. The fiberglass itself may not be a good food source; however, the fiberglass forms a nice nest and traps other food sources. Fiberglass filters, lined fiberglass ducts, and fiberglass panels © 2001 CRC Press LLC
Slide 136: inserted for insulation all become less densely packed with age and use. Particulates, especially those associated with any greasy, vapor-laden airstream, stick to the fiberglass and provide a nutrient bed for biological contamination. Because of the problems with grease or oil in airstreams and biological amplification, care must be taken in using these products. Whenever refrigerant lines bearing mineral oil and freon are serviced, any breakage should be viewed as potentially providing a nutrient “fly paper’’ for biological contaminants. So—how much is bad? This is determined in part by aesthetic concerns and in part by health concerns. If you do not want visible mold growth, even small colonies may be too much. Larger colonies, even if no health effects are forthcoming, are certainly unacceptable and over time may even do structural damage. Aspergillus can thrive on cellulose, paint, and drywall, leaving unpleasant looking stains as the colonies die. The health questions have many answers depending in part on how sampling is accomplished. With current sampling protocols we become concerned if any part of a building is showing amplified mold growth. We often compare to exterior background levels or to levels in a part of the building shown to be relatively free of mold contamination. In the sense that these biological contaminants may be ever changing in numbers as conditions change, there is no such thing as a static background level. The lack of “hard numbers’’ is one other reason that the sampling team and microbiologist oversight must include senior level scientists. For sensitized individuals, the elderly or very young and immune-compromised people, even very sparse mold colonies may cause health problems. Certainly anyone hospitalized for surgery or other invasive medical procedures would also be considered immune compromised during that interval of time. For individuals without these types of concerns, we want to see nonpathogenic mold counts less than 200 CFU/m3 over established background levels. Higher levels may be acceptable for certain mixes of mold species, and lower levels are required for single species and pathogenic contaminant confidence. Contact samples should always be less than 200 CFU/strip for areas to be judged “clean.’’ A combination of contact and air-sampling information is required to assess most buildings (Figure 6.1), and these acceptable numbers vary given different biological contaminant mixes and building usage. For example, in a hospital setting, 20 CFU/strip would be too much in the operating room and perfectly acceptable in the visitor’s waiting room. Once the level of contamination is assessed, we can begin to decide how to remedy any negative situations. Steam cleaning without the use of biocides is sometimes the wrong thing to do. Remember that even steam cools, and cool water is just what most molds need Figure 6.1 Biological contact agar strips. (Biotest Diagnostic Corp.) © 2001 CRC Press LLC
Slide 137: to increase their amplification rate. Steam cleaning can be beneficial with adequate drying cycles and in some instances the concurrent use of biocides. Biocide usage can also be problematic. Chemicals that work in the laboratory may cause aesthetic and even health problems in the real world. Biocides often have limited residual time and may not even be tested against the particular biological contaminant mix of concern. Residual time for any chemical mix has many unresolved questions; sometimes the chemicals’ residual time in your particular circumstances is not even known. In other cases residual time may make the chemical unattractive because the toxic properties of the chemical remain and can cause contamination problems in and of themselves. We must always remember that the basic cellular structure of these biological contaminants and ourselves is the same, so chemicals that harm these contaminants may also harm us. Recently, biocides with FDA and EPA approval have been developed and can be used in areas where biocides were formerly unacceptable. The decision in selecting the appropriate biocide that will not harm humans, animal occupants, or damage structural materials can be a difficult one. Decontamination and rehabitation methodologies must be part of a coordinated remedial design effort. One of the more common replies to all of this information is—why now? The answer is twofold; first, we probably always had these concerns once we lived for any length of time indoors; second, we have increasingly closed our buildings and relied on forced air ventilation systems. Both of these answers are also applicable to closed cab modes of transportation—airplanes, automobiles, rail cars, and ships. In the past we thought that endpoint filtration of airstreams was sufficient to render delivered air relatively pure. We have now learned that filtration only works for a time, and excessive biological amplification can be transmitted through most current HVAC systems once established in ductwork or plenums. If you suspect biological contamination, see visible mold growth, have personnel with repetitive mycosial infections, or have indoor air quality (IAQ) problems that have remained undiagnosed, you need to consult a team of professionals to find answers to these problems. In these cases not only is the mold growth itself problematic, but also we have to worry about the chemicals formed as colonies die. Dieback causes the chemicals formed during decomposition to be spread throughout building, and these are the same VOCs we worry about from chemical spills or misuse. The following sections speak directly to hazards associated with mold and fungi. 6.1 FUNGI, MOLDS, AND RISK When inhaled, microscopic fungal spores or fragments of fungi may cause allergic rhinitis. Because they are so small, mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs and bring on asthma symptoms. The buildup of mucus, wheezing, and difficulty in breathing are the result. Less frequently, exposure to spores or fragments may lead to a lung disease known as hypersensitivity pneumonitis. Molds are present in our exterior environments, and, hopefully, to a lesser extent in our interior environments. People allergic to molds may have allergic symptoms from spring to late fall. The mold season often peaks from July to late summer. Unlike pollens, molds may persist after the first killing frost. Some can grow at subfreezing temperatures, but most become dormant. Snow cover lowers the outdoor mold count drastically, but does not kill molds. After the spring thaw, molds thrive on the vegetation that has been killed by the © 2001 CRC Press LLC
Slide 138: winter cold. In the warmest areas of the world, however, molds thrive year-round and can cause perennial allergic problems. Molds growing indoors can cause perennial allergic rhinitis even in the coldest climates. If indoor areas show signs of amplification identified by visual assessment, air sampling, and contact/liquid sampling, amplification must be suspected. Amplification is the process whereby biological organisms continue to increase over time. If this increase is not controlled, sufficient mold spores and vegetative structures may be present to create indoor air problems. Hot spots of mold growth in the home include damp basements and closets, bathrooms (especially shower stalls), places where fresh food is stored, refrigerator drip trays, house plants, air conditioners, humidifiers, garbage pails, mattresses, upholstered furniture, and old foam rubber pillows. 6.1.1 What Is the Difference between Molds, Fungi, and Yeasts? Molds and yeasts are two groups of plants in the fungus family. Yeasts are single cells that divide to form clusters. Molds consist of many cells that grow as branching threads called hyphae. The seeds or reproductive particles of fungi are called spores. They differ in size, shape, and color among species. Each spore that germinates can give rise to new mold growth, which in turn can produce millions of spores. 6.1.2 How Would I Become Exposed to Fungi That Would Create a Health Effect? The route of exposure may be inhalation or ingestion accompanied by inhalation. When inhaled, microscopic fungal spores or fragments of fungi may cause health problems. Because they are so small, mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs and bring on asthma symptoms. The buildup of mucus, wheezing, and difficulty in breathing are the result. Less frequently, exposure to spores or fragments may lead to a lung disease known as hypersensitivity pneumonitis. 6.1.3 What Types of Molds Are Commonly Found Indoors? In general, Alternaria and Cladosporium (Hormodendrum) are the molds most commonly found both indoors and outdoors throughout the U.S. Aspergillus, Penicillium, Helminthosporium, Epicoccum, Fusarium, Mucor, Rhizopus, and Aureobasidium (Pullularia) are also common. 6.1.4 Are Mold Counts Helpful? Similar to pollen counts, mold counts may suggest the types and relative quantities of mold present at a certain time and place. For several reasons, however, these counts probably cannot be used as a constant guide for daily activities. One reason is that the number and types of spores actually present in the mold count may have changed considerably in 24 h because weather and spore dispersal are directly related. Many of the common allergenic molds are of the dry spore type—they release their spores during dry, windy weather. © 2001 CRC Press LLC
Slide 139: Other molds need high humidity, fog, or dew to release their spores. Although rain washes many larger spores out of the air, it also releases some smaller spores into the air. 6.1.5 What Can Happen with Mold-Caused Health Disorders? Fungi or microorganisms related to them may cause other health problems similar to an allergy. Fungi may lodge in the airways or a distant part of the lung and grow until they form a compact sphere known as a “fungus ball.’’ In people with lung damage or serious underlying illnesses, Aspergillus may grasp the opportunity to invade and actually infect the lungs or the whole body. In some individuals exposure to these fungi can also lead to asthma or to an illness known as “allergic bronchopulmonary aspergillosis.’’ This latter condition, which occurs occasionally in people with asthma, is characterized by wheezing, low-grade fever, and coughing up of brown-flecked masses or mucous plugs. Skin testing, blood tests, X-rays, and examination of the sputum for fungi can help establish the diagnosis. The occurrence of allergic aspergillosis suggests that other fungi might cause similar respiratory conditions. Inhalation of spores from fungus-like bacteria, called actinomycetes, and from molds can cause a lung disease called hypersensitivity pneumonitis. This condition is often associated with specific occupations. Hypersensitivity pneumonitis develops in people who live or work where an air-conditioning or a humidifying unit is contaminated with and emits these spores. The symptoms of hypersensitivity pneumonitis may resemble those of a bacterial or viral infection such as the flu. If hypersensitivity pneumonitis is allowed to progress, it can lead to serious heart and lung problems. 6.2 BIOLOGICAL AGENTS AND FUNGI TYPES A host of fungi are commonly found in ventilation systems and indoor environments. The main hazardous species belong to the following genera: Absidia, Alternaria, Aspergillus, Fusarium, Cladosporium, Cryptostroma, Mucor, Penicillium, and Stachybotrys. Various strains of these genera of molds have been implicated in being causative agents in asthma, hypersensitivity pneumonitis, and pulmonary mycosis. Fungi commonly found in ventilation systems and indoor environments include Absidia, Acremonium, Alternaria, Aspergillus, Aureobasidium, Botrytis, Cephalosporium, Chrysosporium, Cladosporium, Epicoccum, Fusarium, Helminthosporium, Mucor, Nigrospora, Penicillium, Phoma, Pithomyces, Rhinocladiella, Rhizopus, Scopulariopsis, Stachybotrys, Streptomyces, Stysanus, Ulocladium, Yeast, and Zygosporium. Eleven types of fungi are typically found in homes: Aspergillus, Cladosporium, Chrysosporium, Epicoccum, Fonsecaea, Penicillium, Stachybotrys, and Trichoderma. 6.2.1 Alternaria A number of very similar, related species are usually grouped together as Alternaria. The spores of Alternaria are multicelled and developed in chains, head-to-toe, from which their name derives. Spores are multiseptate, both transverse and longitudinally. They vary in width and length according to species, usually 8–75 m long; some species such as A. longissima are up to 0.5 mm long. Alternaria, which is both ubiquitous and abundant, is both saprophytic and parasitic on plant material and is found on rotting vegetation as well as in damp indoor areas, such as bathrooms. Some species of Alternaria are the imperfect, asexual, anamorph spores of the ascomycete Pleospora. © 2001 CRC Press LLC
Slide 140: 6.2.2 Aureobasidium Aureobasidium is common in both outdoor and indoor air, bathroom walls, and shower curtains. Aureobasidium causes mildew and has been isolated in flooded areas of buildings, as well as from soils, plants, and other substrates. Aureobasidium has been associated with hypersensitivity pneumonitis in some individuals. 6.2.3 Cladosporium Cladosporium, composed of over 500 species, is found in outdoor as well as indoor air. Cladosporium has been isolated from fuels, wood, plant tissues, straw, face cream, air, soil, foods, paint, and textiles. Cladosporium spores are often found in higher concentrations in the air than any other fungal spore type. Cladosporium bears copious numbers of spores on branched conidiophores. The spores usually have distinctive “scars’’ at both ends where they are joined both to the spore at one end and to the conidiophore at the other. Although often identified as single-celled spores, spores are frequently seen with a single transverse septum or several transverse septa. Their length ranges from 4 to 20 m. Cladosporium (Hormodendrum) is the most commonly identified outdoor fungus and is a common indoor air allergen. Indoors Cladosporium may be different from the species identified outdoors. Cladosporium is commonly found on the surface of fiberglass duct liners in the interior of supply ducts. Cladosporium can cause mycosis and is a common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms; chronic cases may develop pulmonary emphysema. 6.2.4 Rhodotorula Rhodotorula is a commonly isolated yeast that is frequently isolated from humidifiers and soil. Rhodotorula may be allergenic to susceptible individuals when present in sufficient concentrations. 6.2.5 Stemphylium Stemphylium is a saprophytic fungus (grows on nonliving organic material) commonly found on cellulosic materials (that is, of plant origin, including livestock feed, cotton cloth, ceiling tiles, paper). Stemphylium is an example of a diurnal sporulator. An alternating light and dark cycle is required for spore development. This fungus requires ultraviolet light for the production of conidiophores; however, the second developmental phase, when the conidia are produced, requires a dark period. Stemphylium also requires wet conditions for growth. Stemphylium spores range from 23 to 75 m in length. 6.2.6 Sterile Fungi Sterile fungi are common to both outdoor and indoor air. These fungi produce vegetative growth, but yield no spores for identification. Their presence will increase CFU/l. Derived from ascospores or basidiospores, the spores of which are likely to be allergenic, these fungi should be considered allergenic. © 2001 CRC Press LLC
Slide 141: 6.2.7 Yeast Various yeasts are commonly identified on air samples. Yeasts are not known to be allergenic, but they may cause problems if a person has had previous exposure and developed hypersensitivities. Yeasts may be allergenic to susceptible individuals when present in sufficient concentrations. Yeast grows when moisture, food, and just the right temperatures are available. 6.3 ASPERGILLUS Aspergillus and Penicillium are molds prevalent in soils. These molds can cause asthmalike symptoms or other lung irritation in humans and deterioration in buildings and other materials. When conditions within buildings cause the buildup of moisture on surfaces and temperatures are right, Aspergillus grows well and is evidenced by a black deposit. Aspergillus is a type of mold called Ascomycota or sac fungi. Sac fungi have sexual spores that are produced in an ascus or saclike structure. Their asexual spores, called conidiospores (from the word conidia, which means “dust’’), are produced in long chains from a conidiophore. The characteristic arrangement of the conidiospores is used to identify the different molds. Penicillium is another mold that is also called Ascomycetes. 6.3.1 What Color Are These Molds? Aspergillus is black, and Penicillium is white. Also, Aspergillus is not the black mold on bread. That mold is Rhizopus nigricans. The difference is evident in the differing structures for black asexual spores (sporangiospores). 6.3.2 How Is Aspergillus Spread? Aspergillus spores are carried in the wind and through ventilation airstreams in homes. The asexual spores freely detach from the conidiophore chain and, with the slightest disturbance, float in the air like dust. The easiest way to get Aspergillus started in the home is to bring the spores in on shoes and deposit the spores on carpet fibers. 6.3.3 How Does Aspergillus Grow/Amplify? When the spores are placed on wet surfaces, the spores grow hyphae. The hyphae grow, form a mass, and are soon visible to the naked eye. The vegetative mycelium process foods, and reproductive mycelium create more spores. At this time the mold/fungi appears as a black fuzzy mass. (Amplification is the process whereby Aspergillus or other biological organisms continue to increase in number over time.) 6.3.4 What Conditions Help Aspergillus Grow/Amplify? Fungi generally grow better with an acidic pH. The growth is usually on the surface rather than embedded within a substrate (under the surface). Fungi are able to grow on surfaces with a low moisture content, in contrast to the moisture required for bacterial growth. Therefore, even a slight difference in temperature and surface moisture facilitates the growth of fungi. © 2001 CRC Press LLC
Slide 142: Fungi are capable of using complex carbohydrates, such as lignin (wood). Thus, with a little moisture, fungi can easily grow on wood or other complex organic materials. These adaptations allow fungi to grow readily on painted walls and shoe leather. 6.3.5 Can Mold/Fungi Make You Sick? Fungal diseases are called mycoses, which are chronic, long-lasting infections. Aspergillosis is an opportunistic infection that can become pathogenic (disease-causing) in a weakened individual host. The inhalation of spores is a possible mode of entry into the body as spore size ranges from 2 to 10 m. 6.3.6 What Are the Symptoms of Aspergillosis? The incubation period varies with different individuals. People with other weakening medical problems or general ill health are most susceptible. Aspergillus niger (A. niger) produces mycotoxins that can induce asthma-like symptoms. In situations when A. niger was found growing with Penicillium sp., massive inhalation of spores has been documented as causing an acute, diffuse, self-limiting pneumonitis (lung irritation). Healthy individuals can exhibit otitis externa (inflammation of the outer ear canal) as a result of Aspergillus growth. 6.3.7 Does Aspergillus Cause Deterioration of Materials? Members of the Aspergillus genus are known as biodeteriogens (organisms that cause deterioration of materials). A. niger causes damage, discoloration, and softening of the surfaces of woods, even in the presence of wood preservatives. A. niger also causes damage to cellulose materials, hides, and cotton fibers. A. niger can also attack plastics and polymers (i.e., cellulose nitrate, polyvinyl acetate, polyester type polyurethanes). 6.3.8 What Happens If Aspergillus Colonies Grow inside Construction Layers? In cases of extensive growth, colonies will grow into wood, plaster, and/or drywall, causing a soft bulging area. This area lacks structural integrity and is subject to early deterioration. 6.3.9 How Is Aspergillus Identified? Soy agar will grow Aspergillus and a wide range of other microbiologicals. Thus, Tryptic Soy Agar or Potato Dextrose Agar is the original screening tool used to determine the presence of biologicals. Once biological contamination has been established, selective media can be used to grow suspect organisms for identification. Using a special type of protein gelatin (called Rose Bengal Agar) that has been made with special nutrients, Aspergillus cultures can be selectively and quickly grown. © 2001 CRC Press LLC
Slide 143: 6.3.10 How Are Levels of Aspergillus Communicated? Aspergillus is reported in terms of colony forming units per cubic meter. The presence of any one fungi in excess of 200 CFU/m3 is indicative of an indoor source of fungal amplification. The presence of any colony forming units per cubic meter is indicative of transmission of fungal spores from surface to surface and/or from exterior to interior locations. 6.3.11 Why Do Aspergillus Colonies Look Black? Aspergillus is black or brown-black. Also, active biological contamination creates a surface to which dusts and other debris “stick.’’ If biological contamination is extensive and characterized by amplification and “kill’’ cycle condition, the fungi/molds will decay and produce toxins. These toxins can be identified with Aspergillus contamination as a black stain or tarlike liquid residue. 6.3.12 What Will Biotesting of the Air Show? Biotesting using a BIOTEST air monitor will reveal whether colony forming units are found in the air. Biotesting by surface culturing on agar reveals the presence of biologicals on surfaces and in waters. 6.3.13 What Can Be Done to Prevent Aspergillus Growth? Keep the air dry, provide filtered replacement air, and have sufficient air exchanges. Prevent accumulation of standing water or leaks. 6.4 PENICILLIUM Penicillium is a very large group of fungi valued as a producer of antibiotics. Penicillium is commonly found in the soil; in the air; on living vegetation, seeds, grains, and animals; and on wet insulation. Penicillium has been associated with hypersensitivity pneumonitis in some individuals when it is present in high concentrations. Penicillium is a source of antibiotic lines that have aided humanity. However, not all species of Penicillium are helpful. Some can cause allergic reactions and other adverse health effects when dispersed through indoor air. Currently, more and more is being learned about the effects of Penicillium and other microbiologicals in indoor air. This section represents a starting discussion of the risks associated with the growth of Penicillium within indoor air environments. Penicillium is a fungus that grows when moisture, food, and just the right temperatures are available. Penicillium’s spherical spores are produced in long, unbranched chains of each conidiophore. These usually fragment into individual spores, although chains of spores are seen periodically on slides. Although some species of Penicillium appear to reproduce solely by asexual means, some species of Penicillium are the anamorph (asexual) stage of the ascomycete genus Talaromyces. © 2001 CRC Press LLC
Slide 144: 6.4.1 What Do Samples Look Like? When samples are freshly prepared from culture, the spores are pale green, although this fades with age. Their size ranges from 3 to 5 m. When using visual methods of identification, Aspergillus and Penicillium cannot be differentiated because the spores are so similar that they are grouped together into the Aspergillus/Penicillium group. Spores from this group are found almost all year-round. 6.4.2 What Species of Penicillium Are Used to Produce Antibiotics? Penicillin, as produced by Alexander Fleming in 1929, was a product of Penicillium notatum. Since that time, other species of Penicillium have been used to form other antibiotics. As an example, Griseofulvin is an antifungal antibiotic formed from a species of Penicillium. 6.4.3 What Other Fungi Grow Where Penicillium Grows? Aspergillus, Penicillium, Verticillium, Alternaria, and Fusarium are all found in the order Moniliales and have similar morphology. Thus, where Aspergillus is found, one may expect to find Penicillium and vice versa. The key here is the relative presence of moisture that may accelerate the growth of one particular fungus rather than another. 6.4.4 If Penicillium Grows Everywhere, What Is the Concern? The concern is that, in most cases, we do not want Penicillium growing inside us. This warning is especially true if an individual is immune compromised. People sensitized to Penicillium, the very young, the aging population, and people with certain illnesses, could be considered immune compromised. These individuals may react more strongly (and often more negatively) to some Penicillium species entering their bodies. 6.4.5 How Does Penicillium Enter the Body? The route of entry into the body is unknown. However, the respiratory route is used by many other fungi with abundant conidia. Penicillium may have abundant conidia; thus, the respiratory route of entry is expected. Skin trauma has been associated with local infection, but not with systemic disease. Infection via the digestive route is unusual for filamentous fungi. 6.4.6 Are There Particular Species of Penicillium about Which I Should Be Concerned? Within current medical literature, the primary concern is with Penicillium marneffei (P. marneffei). This species has two life formations and is the only Penicillium species that is termed dimorphic. The prevalence of one form over another is dependent on temperature. At 37°C the fungus grows as yeasts forming white-to-tan, soft, or convoluted colonies. Microscopically, the yeasts are spherical or oval and divide by fission rather than budding. © 2001 CRC Press LLC
Slide 145: At 25°C the fungus produces a fast-growing, grayish floccose colony. Microscopic examination reveals septate branching hyphae with lateral and terminal conidiophores that produce unbranched, broomlike chains of oval conidia. Inside the body P. marneffei first proliferates in the reticuloendothelial system and then is disseminated. The lungs and liver are usually the most severely involved organs. Other commonly involved organs include skin, bone marrow, intestine, spleen, kidney, lymph nodes, and tonsils. The reticuloendothelial system is made up of special cells called phagocytes located throughout the body; they can be found in the liver, spleen, bone marrow, brain, spinal cord, and lungs. When functioning correctly, phagocytes destroy disease-causing organisms by ingesting the organisms. An example of these cells are histiocytes. Histiocytes try to ingest and kill P. marneffei. Unfortunately when the P. marneffei do not die, the histiocytes carry them throughout the body. 6.5 FUNGI AND DISEASE The main hazardous species belong to the following genera: Absidia, Alternaria, Aspergillus, Fusarium, Cladosporium, Cryptostroma, Mucor, Penicillium, and Stachybotrys. Various strains of these genera of molds have been implicated in being causative agents in asthma, hypersensitivity pneumonitis, and pulmonary mycosis. Fungi commonly found in ventilation systems and indoor environments include Absidia, Acremonium, Alternaria, Aspergillus, Aureobasidium, Botrytis, Cephalosporium, Chrysosporium, Cladosporium, Epicoccum, Fusarium, Helminthosporium, Mucor, Nigrospora, Penicillium, Phoma, Pithomyces, Rhinocladiella, Rhizopus, Scopulariopsis, Stachybotrys, Streptomyces, Stysanus, Ulocladium, Yeast, and Zygosporium. 6.5.1 Blastomyces dermatitidis Local infections have occurred following accidental parenteral inoculation with infected tissues or cultures containing yeast forms of B. dermatitidis. Parenteral (subcutaneous) inoculation of these materials may cause local granulomas. Pulmonary infections have occurred following the presumed inhalation of conidia; two individuals developed pneumonia and one had an osteolytic lesion from which B. dermatitidis was cultured. Presumably, pulmonary infections are associated only with sporulating mold forms (conidia). 6.5.2 Coccidioides immitis Clinical disease may occur in 90% of an exposed indoor population. Infections acquired in nature are asymptomatic in 50% of these outdoor cases. Because of their size (2–5 nm), the arthroconidia are conducive to ready dispersal in air and retention in deep pulmonary spaces. The much larger size of the spherule (30–60 nm) considerably reduces the effectiveness of this form of the fungus as an airborne pathogen. Spherules of the fungus may be present in clinical specimens and animal tissues, and infectious arthroconidia may be present in mold cultures and soil samples. Inhalation of arthroconidia from soil samples, mold cultures, or following transformation from the spherule form in clinical materials is the primary hazard. Accidental percutaneous inoculation of the spherule form may result in local granuloma formation. © 2001 CRC Press LLC
Slide 146: 6.5.3 Histoplasma capsulatum Pulmonary infections have resulted from handling mold from cultures. Collecting and processing soil samples from endemic areas have caused pulmonary infections in laboratory workers. Encapsulated spores are resistant to drying and may remain viable for long periods. The small size of the infective conidia (less than 5 m) is conducive to airborne dispersal and intrapulmonary retention. The infective stage of this dimorphic fungus (conidia) is present in sporulating mold from cultures and in soil from endemic areas. The yeast form is in tissues or fluids from infected animals and may produce local infection following parenteral inoculation. 6.5.4 Sporothrix schenckii Sporothrix schenckii has caused a substantial number of local skin or eye infections in laboratory personnel. Most cases have been associated with accidents and have involved splashing culture material into the eye, scratching or injecting infected material into the skin, or being bitten by an experimentally infected animal. Skin infections have also resulted from handling cultures or from the necropsy of animals. No pulmonary infections have been reported to result from laboratory exposure, although naturally occurring lung disease is thought to result from inhalation. 6.5.5 Pathogenic Members of the Genera Epidermophyton, Microsporum, and Trichophyton Skin, hair, and nail infections by these dermatophytid molds are among the most prevalent of human infections. Agents are present in the skin, hair, and nails of human and animal hosts. Contact with infected animals with inapparent or apparent infections is the primary hazard. Cultures and clinical materials are not an important source of human infection. 6.5.6 Miscellaneous Molds Several molds have caused serious infection in immunocompetent hosts following presumed inhalation or accidental subcutaneous inoculation from environmental sources. These agents are Cladosporium (Xylohypha) trichoides, Cladosporium bantianum, Penicillium marnefii, Exophiala (Wangiella) dermatitidis, Fonsecaea pedrosoi, and Dactylaria gallopava (Ochroconis gallopavum). The gravity of naturally acquired illness is sufficient to merit special precautions. Inhalation of conidia from sporulating mold cultures or accidental injection into the skin is a risk. 6.5.7 Fusarium The corn fungus Fusarium moniliforme produces fusaric acid that behaves like a weak animal toxin, but combined with other mold toxins, it exaggerates the effects of the other toxins. Scientists consider that this may be the important role for fusaric acid. All isolates of the Fusarium-type molds produce this toxin, suggesting that this compound is probably more prevalent in the environment than was initially considered. These results indicate © 2001 CRC Press LLC
Slide 147: that analyses and toxicity studies should also include this toxin along with other suspect toxins under field conditions. Fumonisins might be teratogenic to humans. 6.6 FUNGI CONTROL Call in professional help! If you are unsure of the biological condition of your facility or have ongoing unidentified indoor air problems, assume you have a biological emergency. The standing rules are as follows: Bleach what you can bleach. Use biocides with caution. Throw out what you can throw out. If you are unsure about any of these protocols, get help! 6.6.1 Ubiquitous Fungi Fungi are ubiquitous in the environment, particularly in soil, and many are also part of the normal gastrointestinal and skin flora in humans and animals. In some areas of the U.S., certain types of fungi are endemic and occur naturally in the soil. These soil fungi include Histoplasma capsulatum, found in some midwestern states, and Coccidioides immitis, which is found in the southwestern U.S. and parts of Central and South America. If the soil habitat of these fungi is disturbed by activities such as construction or natural disasters, the fungal spores become airborne; when they are inhaled, they can cause infection. 6.6.2 Infection Fungal infections can cause a variety of symptoms. Some types of fungi can infect persons with normal immune systems. Examples are the airborne spores of Blastomyces dermatidis, Coccidioides immitis, or Histoplasma capsulatum, which cause respiratory symptoms ranging from mild illness to pneumonia to severe disseminated disease. Other pathogenic molds, called dermatophytes, cause ringworm infections of the skin, hair, and nails, such as athlete’s foot, jock itch, and scalp ringworm. Unlike most fungi these can be transmitted from person to person. Mushrooms are also fungi, and some can cause life-threatening food poisoning. The fungi that are responsible for the recent increase in mycotic infections are those causing opportunistic infections. These organisms include Candida species, Cryptococcus neoformans, Aspergillus species, Fusarium species, Coccidioides immitis, and Histoplasma capsulatum. Persons at high risk for opportunistic fungal infections are those with HIV infection or AIDS, those who have undergone bone marrow or organ transplants, those receiving chemotherapy for cancer, and others who have had debilitating illness, severe injuries, prolonged hospitalization, or long-term treatment with corticosteroid or antibacterial drugs. 6.6.3 Immediate Worker Protection Whenever possible, use remote methods for cleanup. If you must enter a biological environment, consult a certified industrial hygienist and microbiologist with experience in biological environments. At a minimum, when entering an area where any invasive activities will occur, use HEPA filters for pulmonary protection and wear dermal protection for hands. All material worn or used must be either decontaminated or properly disposed. © 2001 CRC Press LLC
Slide 148: 6.6.4 Decontamination Decontamination may consist of washing with chlorinated or other oxidizing chemicals (i.e., bleach or oxidizing, color-safe bleach; ozone). Biocides may also be used; however, make sure that the biocides are proven effective for the particular biologicals present. All of these chemicals have in and of themselves some risk to workers. For porous surfaces, including fiberglass liners inside ducts, encapsulation of the porous surface may be required. 6.6.5 Fungi and VOCs As molds and fungi grow, they give off emissions of metabolic gases that contain VOCs. Some of the volatile compounds that we have found are primary solvents. Many of these emitted chemicals are identical to those originating from solvent-based building materials and cleaning supplies, including hexane, methylene chloride, benzene, and acetone. 6.6.6 Controlling Fungi Moisture, heat, and dirt or dusts are the ingredients needed to grow fungi. Remove one or more, and you’ll likely have a healthier building. Furnace filters—often used in homes, schools, and small office buildings—don’t catch and trap all the microbes and the dust the microbes feed upon. Consequently, the filters transmit the microbes and catch large particulates for a time and release a certain percentage of the smaller particles (including spores). Then as the filters become dirtier, the filter material itself begins to catch more of the microbes, provides a growth location, and transfers some of the microbial contamination into the airstream. Another hot spot for microbial growth is the humidifier assembly on furnaces. Typical humidifier reservoirs are pools of standing, stagnant water throughout much of the year that allow mold to grow and infiltrate the ducts. In many buildings, fiberglass-lined ductwork (often used for noise or thermal control) is used in lofts because of continual airflow. These lofted spaces collect dirt and become “microbial nests.’’ The microbes grow and multiply and then are blown all over the building to infest other areas. 6.7 ABATEMENT Should removal of contaminated items be the only option, workers and building occupants must be protected during the abatement. Control of airstreams in and out of the contaminated area is a requirement to limit contamination in other areas of building. These biologicals grow and reproduce; therefore concentrations of biologicals are not equivalent to such things as chemical concentrations. A dilute concentration of biologicals in a good growth environment will result in a concentrated level of contamination over time. All abated buildings must be sampled and certified as suitable for reentry prior to normal building usage. This certification states that the building’s biological contamination has been diminished through abatement activities and is now in equilibrium with the ambient exterior conditions or interior baseline conditions previously agreed upon. © 2001 CRC Press LLC
Slide 149: Certification does not state that the building cannot be recontaminated in the future. Always ask for recommendations for preventing future recontamination of your facility. Any porous materials that have been contaminated, removed from the facility, and returned must be decontaminated; facility users must be advised that recontamination may be inevitable. © 2001 CRC Press LLC
Slide 150: CHAPTER 7 Indoor Air Quality and Environments This chapter evaluates the operations and maintenance decisions that must be made for air monitoring appropriate for testing ventilation adequacy. It includes a discussion of current airmonitoring instrumentation and methodology. 7.1 VENTILATION DESIGN GUIDE Mechanical designs should be economical, maintainable, and energy efficient, with full consideration given to the functional requirements and planned life of the facility. Mechanical design should also consider life-cycle operability, maintenance, and repair of the facility and real property–installed equipment, components, and systems. Ease of access to components and systems in accordance with industry standards and safe working practices is a design requirement. The best way to prevent IAQ problems is to have appropriate and effective engineering controls in place to maintain the indoor air quality. The following is an example of design criteria guidance that should be discussed throughout the design phase. Various boxes throughout the chapter illustrate the real-world concerns from which this guidance was derived. 7.2 EXAMPLE DESIGN CONDITIONS GUIDANCE The following conditions should be used and will need to be investigated in designing the mechanical systems: • Site Elevation: Equipment design elevation is {insert} feet (meters) above sea level. Appropriate corrections should be made when calculating the capacity of all mechanical equipment installed at this elevation. • Latitude: {insert} Deg N • Heating Degree Days: {insert} annual • Cooling Degree Days: {insert} annual © 2001 CRC Press LLC