United States
Environmental Protection
Agency
Office of Pesticide
and Toxic Substances
Washington, DC 20460
EPA 560 5-83-002
March 1983
Toxic Substances
Guidance for
Controlling Friable
Asbestos-Containing
Materials in Buildings
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EPA Report Number 560/5-83-002
March 1983
GUIDANCE FOR CONTROLLING
FRIABLE ASBESTOS-CONTAINING
MATERIALS IN BUILDINGS
Field Studies Branch
Design and Development Branch
Exposure Evaluation Division
Office of Toxic Substances
Office of Pesticides and Toxic Substances
U.S. Environmental Protection Agency
Washington, D.C. 20460
Chicago,
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DISCLAIMER
This report was prepared under contract to an agency of the United States Government.
Neither the United States Government nor any of its employees, contractors, subcontractors,
or their employees makes any warranty, expressed or implied, or assumes any legal liability or
responsibility for any third party's use of or the results of such use of any information,
apparatus, product, or process disclosed in this report, or represents that its use by such third
party would not infringe on privately owned rights.
Publication of the data in this document does not signify that the contents necessarily reflect
the joint or separate views and policies of each sponsoring agency. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
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TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS v
EXECUTIVE SUMMARY vii
CHAPTER 1 — EXPOSURE TO ASBESTOS INSIDE BUILDINGS 1-1
1.1 Health Effects Related to Asbestos Exposure 1-1
1.2 EPA and OSHA Regulations Related to Asbestos 1-2
1.3 Airborne Asbestos Levels in Buildings and the Potential Health Risk 1-4
CHAPTER 2 — DEVELOPING A CONTROL PROGRAM 2-1
2.1 Establishing Responsibility 2-2
2.2 Planning 2-2
2.3 Obtaining Advice 2-4
2.4 Implementing Corrective Measures 2-5
2.5 Recordkeeping 2-7
CHAPTER 3 — DETECTING ASBESTOS, ASSESSING THE PROBLEM,
AND SELECTING A COURSE OF ACTION 3-1
3.1 Inspecting, Sampling, and Analyzing for Asbestos 3-2
3.2 Assessing the Potential for Exposure to Asbestos 3-6
3.2.1 Principles of Fiber Release, Suspension, and Transport 3-6
3.2.2 Estimating the Potential for Fiber Release 3-6
3.2.2.1 Proposed Exposure Indices 3-6
3.2.2.2 Usefulness of Individual Assessment Factors 3-7
3.2.3 Measuring Airborne Asbestos 3-8
3.3 Asbestos Control Measures 3-11
3.3.1 Control Alternatives for Material Sprayed or Troweled on Surfaces ... 3-11
3.3.1.1 Removal, Disposal, and Replacement 3-14
3.3.1.2 Enclosure 3-18
3.3.1.3 Encapsulation with Sealants 3-20
3.3.1.4 Special Operations and Maintenance Procedures
and Periodic Reassessment 3-22
3.3.2 Control Measures for Pipe and Boiler Insulation 3-22
3.4 The Decision-Making Process 3-24
CHAPTER 4 — DETERMINING ABATEMENT COMPLETION 4-1
4.1 Visual Inspection 4-1
4.2 Air Monitoring 4-1
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TABLE OF CONTENTS
(Continued)
Page
REFERENCES R-1
APPENDICES
Appendix A. Common Units Used in Measuring Airborne
Asbestos Concentrations A-1
Appendix B. Addresses of EPA Regional Asbestos Coordinators B-1
Appendix C. Asbestos-Containing Materials Found in Buildings C-1
Appendix D. Definition and Description of Factors for Assessing
the Need for Corrective Action D-1
Appendix E. Example Building Inspection Form E-1
Appendix F. Recommended Specifications and Operating Procedures for the Use
of Negative Pressure Systems for Asbestos Abatement F-1
Appendix G. Estimation of Fiber Detection Limit Using the NIOSH Membrane
Filter Method (P&CAM 239) G-1
Appendix H. Glossary H-1
LIST OF TABLES
Table 1. Organization of Factors for Assessing Fiber Release Potential 3-8
Table 2. Comparison of Asbestos Control Alternatives 3-27
Table 3. Total Airborne Fiber Detection Limits and Associated Sampling Volumes ... 4-2
Table C-1. Various Types of Friable and Nonfriable Materials and Products C-2
LIST OF FIGURES
Figure 1. Comparison of Measured Airborne Asbestos
Concentrations in Three Settings 1-5
Figure 2. Control Program Organization 2-2
Figure 3. Examples of Friable and Nonfriable Asbestos-Containing
Materials Found in Buildings 2-3
Figure 4. Steps in Investigating for the Presence of Asbestos 3-3
Figure 5. Types of Building Materials Which Could Contain Asbestos 3-4
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LIST OF FIGURES
(Continued)
Page
Figure 6. Example Assessment Characteristics of Asbestos-
Containing Materials 3-9
Figure 7. An Example of the Effect of a Change in Building Use 3-10
Figures. Asbestos-Containing Material Located Above a Suspended Ceiling 3-13
Figure 9. Construction of Containment Barriers 3-15
Figure 10. An Asbestos Removal Project 3-16
Figure 11. An Asbestos Enclosure Project 3-19
Figure 12. An Asbestos Encapsulation Project 3-21
Figure 13. Pipe Insulation in Damaged & Deteriorated Condition 3-23
Figure 14. Custom Containment Bags for Repairing or Removing Pipe Insulation ... 3-24
Figure 15. A Guide to Selecting a Course of Action 3-25
Figure F-1. Sketch of HEPA-Filtered Exhaust Unit F-2
Figure F-2. Examples of Negative Pressure Systems F-6
in
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Acknowledgments
The assistance of the many individuals who contributed their time and efforts to the
preparation of this document are gratefully acknowledged. Dale Keyes, an independent
consultant, and Bertram Price of Battelle Memorial Institute served as primary authors of the
document. They prepared the initial draft and revised it to reflect a series of detailed reviews.
Joseph Breen and Cindy Stroup (Office of Toxic Substances, Exposure Evaluation Division)
served as Task Managers and directed the report preparation process. The material presented
here reflects many hours of discussion among local school officials, health and environmental
scientists, architects, engineers, and staff at EPA Headquarters and in the Regional Offices.
The document was developed and refined through a series of meetings with three groups—a
working group consisting of EPA staff from the Office of Toxic Substances (OTS); a larger
review group consisting of the OTS working group, EPA staff from the Office of Research and
Development (ORD), and Regional Asbestos Coordinators from EPA Regional Offices; and a
peer review group consisting of school officials and technical specialists who are not EPA
employees.
The OTS working group provided thorough and timely criticism, suggestions, and assistance
in formulating the presentation of the more complex issues. The working group members
were:
Joseph Breen, Exposure Evaluation Division
James Bulman, Chemical Control Division
Dave Mayer, Chemical Control Division
Richard McAllister, Chemical Control Division
Cindy Stroup, Exposure Evaluation Division
The larger EPA review group met early in the process to outline the document and to decide
which areas needed to be emphasized. In addition to persons listed above, the group
consisted of:
Michael Beard, Office of Research and Development/Environmental Monitoring
Systems Laboratory
Wolfgang Brandner, EPA Region VII
Dwight Brown, EPA Region IV
William Cain, Office of Research and Development/Industrial Environmental
Research Laboratory
Carol Grove, Office of Research and Development/Center for Environmental
Research Information
Pamela Harris, Office of Pesticides and Toxic Substances/Enforcement Division
Tony Restaino, EPA Region V
Gilbert Wood, Office of Air Quality Planning and Standards/Emission Standards
Engineering Division
The members of this group were also active participants in the three-day peer review
meeting. We thank all of them for their contributions.The Regional Asbestos Coordinators
deserve special recognition. Their insights and suggestions based on experience gained in the
field were invaluable. Wolfgang Brandner was especially helpful in providing details about
specific evaluation and assessment procedures developed in Region VII.
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The peer review group members were:
Gene Brantly, Research Triangle Institute, Research Triangle Park, North Carolina
Ron Goodwin, The School District of Greenville County, South Carolina
Don W. Handley, The School District of Philadelphia, Pennsylvania
Ernest Lory, Port Hueneme, California
William Nicholson, Mt. Sinai School of Medicine, City University of New York, New
York, New York
Patrick Sebastien, Institute of Occupational Health & Safety, McGill University,
Montreal, Quebec
George Smart, George Smart Architects, Inc., Raleigh, North Carolina
Their active participation in the peer review meeting, the speed with which they reviewed all
drafts, and their commitment and dedication to the task of disseminating information and
guidance for the control of exposure to airborne asbestos are greatly appreciated.
Other contributors participated at various stages in the report preparation. In particular, we
wish to thank Project Officers Joseph Carra and Frederick Kutz (Office of Toxic Substances,
Exposure Evaluation Division), Suzanne Rudzinski (Office of Toxic Substances, Chemical
Control Division), John Lerohl (Office of Toxic Substances, Chemical Control Division), and
Donald Lentzen (Research Triangle Institute).
Special appreciation is extended to Ms. Terri Stiteler of Battelle who assisted in analyzing and
incorporating comments of the review groups, organizing review group sessions, and
directing the preparation and distribution of drafts and the final document.
The Dynamac Corporation is also acknowledged for its role in organizing the peer review
meeting, as well as other support staff at EPA and at Battelle for contributing to the successful
completion of the project.
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Executive Summary
The Environmental Protection Agency (EPA) has been concerned about the disease-causing
potential of exposure to airborne asbestos in nonindustrial settings since the early 1970s. In
the late 1970s, attention was focused on schools and other buildings where asbestos is
present in a variety of construction materials. EPA initiated a Technical Assistance Program
(TAP) to help school districts identify and correct potential asbestos hazards. As part of this
program, in 1979 EPA prepared and distributed "Asbestos-Containing Materials in School
Buildings: A Guidance Document," Parts 1 and 2, which describes how to establish an
asbestos identification and control program. It provides both background information and
direction for school officials on exposure assessment and the control of asbestos-containing
materials.
During the four years since publication of the guidance document, EPA has gathered
additional information and has gained valuable experience in assessing the need for
corrective action and in controlling the release of fibers from asbestos-containing materials.
The purpose of the present document is to supplement previous EPA guidance by emphasizing
recent experience and new information on asbestos control. The guidance is important not
only for school officials, but also for building owners in general who may have to consider
implementing an asbestos control program.
The document serves six specific functions:
(1) To provide a current summary of data on exposure to airborne asbestos;
(2) To identify organizational and procedural issues in establishing an asbestos
control program;
(3) To review technical issues confronted when assessing the potential for exposure
to airborne asbestos in particular indoor settings;
(4) To summarize and update information on the applicability, effectiveness, and
relative costs of alternative remedial actions;
(5) To suggest a structured process for selecting a particular course of action, given
information on exposure levels, assessment methods, and abatement tech-
niques; and
(6) To introduce and discuss criteria for determining successful asbestos control.
Substantial scientific uncertainty accompanies many of the technical considerations in the
assessment of exposure to airborne asbestos, and the success of any specific abatement
action often depends on the circumstances in which it is undertaken. Nevertheless, decisions
regarding the need for and types of control must be made. For those readers who previously
have been involved in the Asbestos-in-Schools program, the guidance offered will serve as a
review and update of familiar issues. For those confronted with the problem of controlling
asbestos for the first time, the document will identify the critical issues, introduce information
on asbestos exposure and control, and direct the reader toward the structured development of
an asbestos control program.
The focus of this report is asbestos-containing material in friable form. Friable materials have
a greater potential for fiber release and thus pose a greater hazard than other forms of
asbestos-containing materials. Nonfriable materials which contain asbestos also are
addressed, but only regarding the need for documentation and periodic inspection.
The report is organized in four chapters. Background information on health risks and asbestos
exposure levels is presented in Chapter 1. Chapter 2 emphasizes the organizational and
VII
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procedural aspects of developing and managing an asbestos control program. Chapter 3
discusses the key technical issues associated with assessing the need for corrective action
and selecting an asbestos control measure. Chapter 4 focuses on criteria for determining that
an asbestos abatement project has been successfully completed. The key issues and
recommendations are summarized at the beginning of each chapter and are provided below.
Health Effects and Exposure
• Exposure to airborne asbestos, regardless of the level, involves some health risk.
• Children and young adults who are exposed to asbestos have a greater chance
than older people of developing certain asbestos-related diseases, due to a longer
remaining lifespan during which disease may develop. Also, smokers exposed to
asbestos are at greater risk than nonsmokers experiencing a similar level of
exposure.
• Prevalent levels of airborne asbestos inside buildings where asbestos-containing
materials are present may exceed outdoor levels by a factor of 100. However,
these indoor levels are lower by a factor of at least 1,000 than historic asbestos
workplace levels where the occurrence of asbestos-related disease is well
documented. When asbestos-containing materials are damaged, peak levels
inside buildings may approach historic workplace levels.
• Current regulations restrict the use of asbestos in new buildings, specify work
practices during the removal of asbestos-containing materials from existing build-
ings, and require the identification of asbestos in schools. No exposure standards
have been established for nonindustrial settings, and no regulations mandate
which corrective actions need to be taken in buildings where asbestos-containing
materials are found.
• The potential for exposure to airborne asbestos in buildings and the associated
risk of asbestos-related disease cannot be ignored. The decision whether or not to
take action and the selection among alternative courses of action are the respon-
sibility of the individual building owner.
Developing a Control Program
• A building owner should delegate the responsibility for directing and managing
the control program activities to one individual. This person is called the asbestos
program manager.
• A program plan is needed to address:
— detection of asbestos-containing materials;
— assessment of the exposure potential;
— evaluation of control options;
— management of a control program; and
— recordkeeping.
• Managing a control program is a complex undertaking requiring:
— identification and selection of technical experts;
— training of control program staff;
— selection of contractors;
— supervision of workers; and
— recordkeeping.
VIII
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Implementing a Control Program
• Buildings should be inspected for friable materials, and building records should be
checked for specifications of both friable and nonfriable asbestos-containing
materials.
• Friable materials should be sampled and analyzed for the presence of asbestos.
Procedures for sampling and analysis are described in previous EPA guidance.
• If asbestos-containing materials are present, the need for corrective action should
be assessed. Assessment factors identified in previous EPA guidance are useful
qualitative tools. Numerical scoring and index systems have not proven reliable.
Air monitoring as a tool for assessing the need for corrective action is not
recommended at this time. However, air monitoring may play a role in determining
the successful completion of abatement projects, as noted below.
• Four control alternatives should be considered: removal, enclosure, encapsulation,
and a special maintenance and operations program.
• Specific cleaning procedures should be instituted to reduce levels of airborne
asbestos while waiting for an abatement action to begin.
• A continuing program of special maintenance and periodic reassessment is
needed even after an abatement has been completed, unless the asbestos-
containing material has been removed.
Determining Abatement Completion
• Visual inspection should be conducted to ensure that all work is complete and that
the worksite is free of dust and debris.
• Air monitoring of total airborne fibers by phase contrast microscopy should
supplement visual inspection to determine project completion. The use of air
monitoring in this situation does not establish that the building is free of airborne
asbestos fibers after abatement. Rather, it is used to determine that elevated fiber
levels resulting from the abatement work have been reduced.
IX
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CHAPTER 1 — EXPOSURE TO ASBESTOS INSIDE BUILDINGS
The Environmental Protection Agency (EPA) has been concerned with the disease-causing
potential of nonindustrial exposure to asbestos since the early 1970s. The concern derives
from epidemiologic evidence linking airborne asbestos exposures by asbestos workers to
various types of cancer and nonmalignant respiratory diseases, and from recognition that
large quantities of asbestos have been found in building materials, insulation, and other
products used in schools and other buildings. This chapter (1) summarizes information on the
relationship between health effects and exposure to airborne asbestos; (2) describes federal
regulations affecting asbestos emissions, the use of asbestos materials, and worker exposure
levels; and (3) compares levels of airborne asbestos in buildings with those in asbestos
workplace settings and outdoors. The purpose of the chapter is to place in perspective
asbestos exposure levels and health risks likely to be experienced by occupants of buildings
with asbestos-containing materials. The basic exposure-risk issues are summarized below.
Safe Level of Exposure: EPA and the scientific community believe that any level of
exposure to asbestos involves some health risk, although the exact degree of risk
cannot be reliably estimated. The risk of cancer is of greater concern at low
exposure levels than the risk of asbestosis.
Special Concerns: Children and young adults who are exposed to asbestos have a
greater chance than older people of developing certain asbestos-related diseases
due to a longer remaining lifespan during which disease may develop. Also,
smokers exposed to asbestos are at greater risk than nonsmokers with a similar
level of exposure.
Federal Regulations Affecting Asbestos in Buildings: Current regulations restrict
the use of asbestos in new buildings, specify work practices during removal of
asbestos-containing materials from existing buildings, and require the identification
of asbestos in schools. No exposure standards have been set for nonindustrial
settings, and no regulations mandate corrective actions in buildings where
asbestos-containing materials are found.
Relative Exposure Levels in Buildings: Prevalent levels of airborne asbestos inside
buildings where asbestos-containing materials are present may exceed outdoor
levels by a factor of 100. However, these indoor levels are lower by a factor of at
least 1,000 than historic asbestos workplace levels where the occurrence of
asbestos-related disease is well documented. When asbestos-containing materials
are damaged, peak levels inside buildings may approach historic workplace levels.
Need for Action: The level of airborne asbestos in buildings with asbestos-
containing materials represents a potential for exposure and risk of asbestos-related
disease that cannot be ignored. The decision whether or not to take action and the
selection among different courses of action are responsibilities of individual building
owners.
1.1 Health Effects Related to Asbestos Exposure
Exposure to high levels of airborne asbestos is associated with a debilitating lung disease
called asbestosis; a rare cancer of the chest and abdominal lining called mesothelioma; and
cancers of the lung, esophagus, stomach, colon, and other organs. The relationship between
exposure level and health risk is complex. The best available data on asbestos worker
exposure indicate that the risks of asbestosis, lung cancer, and mesothelioma decrease in
direct proportion to a decrease in total asbestos exposure (the average airborne asbestos
1-1
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concentration multiplied by the duration of exposure). At exposure levels below those allowed
for asbestos workers, the risk of asbestosis is negligible. Some scarring of lung tissue may
appear on X-rays after many years of low exposure, but no impairment of respiratory function
is likely to occur. However, the incidence of lung cancer and mesothelioma exceeds baseline
rates even at very low exposure levels. This conclusion is supported by the increased
incidence of lung cancer for workers experiencing the equivalent of five years' exposure to
airborne asbestos at the current federal workplace standard (USEPA 1982). In addition,
mesothelioma has been found in persons whose only known exposure to asbestos was from
living in a household with asbestos workers or in the neighborhood of asbestos mines, mills,
or processing facilities (USEPA 1982).
Asbestos-related lung cancer usually appears after age 45, and its occurrence is heavily
influenced by cigarette smoking. For example, in one study of asbestos workers, smokers
experienced a fiftyfold increased incidence of lung cancer compared with similarly-aged
workers who neither smoked nor were exposed to asbestos. Among the nonsmoking asbestos
workers, only a fivefold increase in incidence was found (USEPA 1982).
The age at which asbestos exposure occurs is relatively unimportant for determining the
lifetime risk of lung cancer for people less than 45 years old. Asbestos inhaled at age 1 5 has
virtually the same effect in terms of lifetime risk as asbestos inhaled at age 40. In contrast
with lung cancer, the age at which asbestos exposure occurs is very important in determining
the lifetime risk of developing mesothelioma. This fact creates a special concern for asbestos
exposure in children. Studies of workplace exposure indicate that, for persons exposed for
several years, the probability of developing mesothelioma remains constant for an initial
period and then increases continuously with time from onset of exposure. Since children have
a greater remaining lifespan than adults, their lifetime risk should be greater. For example,
asbestos workplace studies suggest that a child exposed from age 5 to 10 has at least 10
times the chance of developing mesothelioma as does an adult exposed to the same amount
of asbestos between ages 35 and 40.*
1.2 EPA and OSHA Regulations Related to Asbestos
Both EPA and the Occupational Safety and Health Administration (OSHA) have published
regulations to reduce exposure to asbestos. The EPA rules have focused on two aspects of
asbestos in buildings: (1) the application of asbestos-containing materials in new or
remodeled buildings, and (2) the identification of friablef asbestos in schools. In addition to
these rules, EPA has regulated the emission of asbestos fibers from the handling of asbestos
in asbestos industries and the disposal of asbestos-containing waste. The OSHA regulations
address worker protection in asbestos workplaces.
EPA has issued two sets of regulations. The first set was promulgated under the National
Emission Standards for Hazardous Air Pollutants (NESHAPS) as authorized in the Clean Air
Act. This set of regulations includes a 1973 ban on the use of spray-applied asbestos-
containing materials in buildings for insulating or fireproofing purposes, except for equipment
and machinery, as well as the specification of "no visible emissions" from permitted spraying,
as published in the FEDERAL REGISTER (38 FR 8826).ft Methods of removing friable
asbestos from buildings during demolition also were regulated at this time. The ban was
amended in 1975 to include molded and wet-applied insulation, as published in the FEDERAL
REGISTER (40 FR 48292). In addition, rules governing asbestos removal were broadened to
include building renovation, and procedures for disposal of removed materials were defined.
Finally, the ban on spraying asbestos-containing materials was broadened in 1 978 to include
* Personal communication with William Nicholson, Mt. Sinai School of Medicine, 1982.
t The difference between friable and nonfriable materials is discussed in the introduction to Chapter 2.
ft Materials with less than 1 percent of asbestos by weight were excluded from the ban.
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decorative applications, but also was clarified to exclude all applications covered with a
particular type of nonfriable material, as published in the FEDERAL REGISTER (43 FR 26372).
In addition to these regulations, emission standards have been promulgated under NESHAPS
for asbestos mills, asbestos manufacturing facilities, and asbestos fabrication plants. (See 40
CFR, Part 61, Sections A and B for a compilation of all asbestos regulations issued under
NESHAPS.)
The second set of EPA regulations is contained in the "Friable Asbestos-Containing Materials
in Schools, Identification and Notification Rule," as published in the FEDERAL REGISTER (47
FR 23360). Known as the Asbestos-in-Schools rule, it requires all private and public primary
and secondary schools to inspect, sample, and analyze friable materials to determine if
asbestos is present. If friable asbestos is present, all school employees must be informed of
the location of these materials and each custodial or maintenance employee must be provided
a copy of the EPA publication, "A Guide for Reducing Asbestos Exposure," as published in the
FEDERAL REGISTER (47 FR 23360). In addition, the school's parent-teacher group (or
parents, if there is no organized group) must be notified of the presence of friable asbestos.
The OSHA regulations were first issued in 1972 and modified in 1976. (See 29 CFR, Part
1 910 for the complete text.) They specify airborne exposure standards for asbestos workers,
engineering and administrative controls, workplace practices, and medical surveillance and
worker protection requirements. In 1982, OSHA announced its intention to make the
exposure standards more stringent.* (See the "Calendar of Federal Regulations," published
in the FEDERAL REGISTER [47 FR 1807].) The OSHA regulations apply to all workplace
activities involving asbestos, including removal of asbestos-containing materials from
buildings.
Although the NESHAPS and OSHA regulations include standards to reduce exposure to
airborne asbestos, the standards were designed primarily to protect the health of people living
near asbestos plants, working in the asbestos industry, or removing asbestos from buildings.
Exposure to asbestos by persons occupying buildings with asbestos-containing materials is
not addressed directly by the standards. Specifically, EPA's NESHAPS for asbestos are
directed only at emissions into the outside air (no "visible emissions" resulting from
asbestos-handling operations) and do not apply to indoor levels.
OSHA provides specific worker exposure standards, but the application of these standards to
nonindustrial settings is inappropriate for two reasons. First, the current standards were set
to protect workers against only asbestosis, not cancer. Second, the measurement technique
for airborne fibers required to determine OSHA compliance cannot distinguish between
asbestos and nonasbestos fibers. The measurement problem is not a major shortcoming in
industrial settings where most airborne fibers are expected to be asbestos. However, airborne
asbestos may represent only a small fraction of all fibers in the air in buildings, and the OSHA
measurement technique may produce misleading conclusions. (Other limitations of the
OSHA technique further confound the measurement of airborne asbestos in buildings. See
Chapter 3, Section 3.2.3, for a more detailed discussion of measuring airborne asbestos.)
EPA's concern about potential indoor exposure is reflected in the Asbestos-in-Schools rule.
Its intent is to reduce exposure to asbestos by locating asbestos-containing materials and
alerting school employees and parents of school children to the presence of asbestos.
However, standards for allowable airborne asbestos concentrations or exposure levels are not
specified.
*As of July 1, 1976, the OSHA standards were set at 2 fibers per cubic centimeter averaged over 8
hours and a ceiling level not to exceed 10 fibers per cubic centimeter "at any time". OSHA is now
evaluating the effect of lowering the 8-hour standard to either 0.5 or 0.1 fibers per cubic centimeter in
order to protect workers against cancer, as published in the FEDERAL REGISTER (47 FR 1807).
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1.3 Airborne Asbestos Levels in Buildings and the Potential Health Risk
Although quantitative estimates of the health risk from exposure to asbestos in buildings are
not reliable, a general sense of the risk can be obtained by comparing levels of airborne
asbestos measured in buildings with those observed outdoors and in asbestos workplaces.
Historical workplace data will be used, since much of the evidence linking asbestos exposure
with specific diseases is based on industrial exposure before 1970.
Most investigations of airborne asbestos are designed to measure prevalent concentrations,
that is, air levels observed under normal conditions. Higher ("peak") levels that may result
from damage to asbestos-containing materials in buildings typically are not reflected in these
measurements. Figure 1 provides a graphic summary of data on prevalent concentrations of
airborne asbestos in three types of settings: asbestos manufacturing or application facilities
before imposition of the OSHA standard in 1972, schools where asbestos-containing
materials are present, and outdoor locations in urban areas. In order to facilitate comparison,
all data are expressed in nanograms per cubic meter (ng/m3) units.* The range of values
within each category reflects differences in the location and strength of asbestos sources as
well as variability in asbestos measurements. Concentrations above the upper limits of these
ranges may occur for short periods if, for example, manufacturing equipment malfunctions,
insulating material is pierced with a sharp object, or asbestos-coated surfaces are disturbed
by the impact of a projectile (for example, a ball bounced against a ceiling).
\
Comparing the values in Figure 1, one can see that airborne asbestos levels in buildings with
asbestos-containing materials can be substantially higher than outdoor levels, but signifi-
cantly lower than concentrations to which asbestos workers have been exposed. Prevalent
concentrations of airborne asbestos found in a sample of schools are approximately 100 times
higher than outdoor concentrations. Compared with historic levels of asbestos in workplaces,
airborne asbestos in these schools is lower by a factor of between 1,000 and 10,000.
However, short-term peak levels in buildings may be elevated considerably, perhaps approach-
ing dustrial levels.
Comparison of the data in Figure 1 should be made with some caution. The estimates of
concentrations in asbestos workplaces are based on measurements of airborne fibers using
the measurement method specified by OSHA (phase contrast microscopy), while the levels in
schools and outdoors were measured by a different method (electron microscopy). Compari-
sons of measurements obtained by the two methods are based on certain assumptions
presented in the footnote to Figure 1. The measurement of airborne asbestos fibers is a
complex subject and is discussed in more detail in Section 3.2.2.
Questions of measurement comparability notwithstanding, the presence of significant levels
of airborne asbestos in buildings with asbestos-containing materials has been clearly
established. The potential for exposure to asbestos by building occupants cannot be ignored.
Even though exposure levels are likely to be low in comparison with industrial levels, any
additional exposure above background (outdoor) levels should be avoided if possible. A
prudent response by building owners requires recognition of the potential hazards and
serious consideration of appropriate abatement actions.
•Concentrations of asbestos fibers in the air are measured in terms of either the number of fibers per
unit volume (typically, a cubic centimeter) or the mass per unit volume (typically, nanograms per cubic
meter). A nanogram is one-billionth of a gram. See Appendix A for a simple discussion of
measurement units used for airborne asbestos concentrations.
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Figure 1. Comparison of measured airborne asbestos concentrations in three settings.*
Asbestos insulation
workplaces before 1 970
(Nicholson, personal
communication, 1982)
School buildings
(Constant, et al 1982)
Outdoor ambient air ^^^^
(Nicholson, et al 1971)
J I I I I I
01 10 10 100 1,000 10,000 100,000 1,000,000 10,000,000
Nanograms per cubic meter
-Range-
25% 75%
Percentiles
"Levels in asbestos workplaces were derived from measurements using phase contrast microscopy (PCM) while
levels in school buildings and outdoors were measured using electron microscopy (EM). PCM and EM
measurements are not directly comparable. PCM measures all fibers whereas EM can distinguish between
asbestos and nonasbestos fibers. In addition, EM has a better capability than PCM for detecting small fibers. In
order to translate the workplace PCM measurements (expressed as fiber counts) into values of asbestos mass
(nanograms) that are approximately comparable to EM measurements, 30 fibers were assumed to equal one
nanogram. This value is an average obtained from many comparisons of PCM and EM measurements taken at
the same location (industrial settings) and time. Values for individual samples range from about 10 fibers per
nanogram of asbestos to well over 100 fibers per nanogram, depending on the average size of fibers and the
relative number of asbestos and nonasbestos fibers in the air (Versar 1980 and William Nicholson, personal
communication, 1982).
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CHAPTER 2 — DEVELOPING A CONTROL PROGRAM
An asbestos control program for schools and other buildings begins with an investigation for
evidence of asbestos-containing materials. If the presence of asbestos is confirmed, the
program proceeds with an assessment of the need for corrective action, the implementation
of asbestos control measures, and, if necessary, periodic reassessment.
This chapter addresses issues related to the organization and management of an asbestos
control program for buildings where the presence of asbestos is suspected. Based on the
experience of several school boards over the last few years, the development and execution of
a successful asbestos control program involve the following activities:
Establishing Responsibility: An asbestos program manager is designated and is
given the responsibility for directing and managing control program activities. The
program manager obtains guidance from the appropriate EPA Regional Asbestos
Coordinator (RAC) and becomes familiar with the key organizational, procedural,
and technical elements of an asbestos control program.
Planning: A program plan is developed to guide and schedule the program activities.
Selecting Advisors and Obtaining Advice: The program manager identifies tech-
nical advisors and experts who will assist in plan development and implementation.
Implementing Corrective Measures: Corrective measures may be implemented by
in-house staff or by a contracting firm. If in-house staff or persons initially
unfamiliar with methods of asbestos control are to participate, they must be
thoroughly trained and provided with adequate protective devices. If the need for
corrective action involves the employment of abatement contractors, serious atten-
tion should be given to contractor selection and project surveillance.
Recordkeeping: Detailed records of all program activities, decisions, and analyses
are maintained.
Figure 2 is a chart of the general control program organization.
This chapter emphasizes planning and management. The activities listed above are discussed
in that context. Chapters 3 and 4 discuss important technical issues involved in executing
specific aspects of the program plan.
Since asbestos-containing materials are present in buildings in many forms, it is important for
this discussion to identify those that constitute the greatest potential hazard.* Most efforts to
reduce asbestos levels in buildings have focused on friable materials, that is, materials that
can be crumbled, pulverized, or reduced to powder by hand pressure. (The Asbestos-in-
Schools rule issued in May 1982 addresses only friable asbestos-containing materials.)
Friable materials are generally believed to have a higher potential for fiber release than
nonfriable materials. As a result, the starting point for most asbestos control programs is an
inspection for friable materials in the building. Typically, friable materials have been sprayed
or troweled onto surfaces for fireproofing, insulation, soundproofing, or decoration. Non-
friable materials cannot be ignored because they also may release fibers if disturbed or
mechanically altered during building repair-or remodeling, or if damaged during normal
*Asbestos-containing materials may be found in schools and other buildings in the form of cement
products, acoustical plaster, fireproofing textiles, vinyl floor tiles, thermal insulation, and other
construction materials. Descriptions of these and other asbestos-containing materials appear in
Appendix C.
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Figure 2. Control program organization.
Building owner
Technical
advisors and
experts
Asbestos
program
manager
EPA regional
asbestos
coordinator
Abatement
workers
Administrative
staff
*The technical expert(s) may be delegated authority to direct and/or monitor asbestos abatement activities
building use. However, the need for corrective action is focused on friable asbestos-
containing materials. Documentation and surveillance are recommended for nonfriable
materials which contain asbestos. Figure 3 shows pictures of both friable and nonfriable
asbestos-containing materials in buildings.
2.1 Establishing Responsibility
Responsibility for potential asbestos exposure in a building rests with the building owner. In
schools, this responsibility belongs to the governing official(s) of the local education agency.
Typically, the task of organizing the control program is assigned to an individual with
responsibility for building construction or maintenance. This person, the asbestos program
manager, should become familiar with general procedures for detecting asbestos, methods
for assessing exposure potential, and techniques for controlling asbestos release. The office
of the EPA Regional Asbestos Coordinator (RAC) is a good starting point for obtaining
information on asbestos in buildings. As the building owner's representative, the program
manager guides the entire control program and is the focal point for communication with the
building owner.
2.2 Planning
The asbestos program manager first determines if asbestos is present and outlines a plan for
a comprehensive control program. A plan for a control program may include the following
activities:
• Inspect, sample, and analyze (by polarized light microscopy [PLM]) friable material
to detect asbestos (see Section 3.1).*
• Assess the need for corrective action at sites with asbestos (see Section 3.2).
*Since disturbance of nonfriable asbestos-containing materials should be avoided, sampling and
analysis are usually limited to friable materials. Requirements for asbestos identification in the
Asbestos-in-Schools rule apply to friable materials only.
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Friable, fluffy sprayed-on material
Friable, cementitious sprayed-on or troweled
material (acoustical plaster)
Nonfriable wallboard with friable sprayed-on
material behind
Friable material on beam with nonfnable pipe
insulation below
Figure 3. Examples of friable and nonfriable asbestos-containing materials found in buildings.
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• Implement interim control procedures (see Section 3.3).
• Evaluate and select among alternative abatement or special operations and
maintenance measures (see Sections 3.3 and 3.4).
• Develop a bidding process if an abatement contractor is needed (see Section 2.4).
• Direct and/or monitor abatement activities, and evaluate contractor performance
for those projects undertaken by an abatement contractor (see Sections 2.4, 4.1,
and 4.2).
• Monitor building maintenance activities on a continuing basis if asbestos-
containing materials have not been completely removed (see Sections 2.4 and
3.3).
• Maintain records of survey results and all remedial actions (see Section 2.5).
The plan should include a list of the tasks required, a description of work practices and a
time schedule for completion of each task.
The first five activities listed above focus on detecting asbestos and selecting a strategy for
controlling asbestos if it is present. As noted. Chapter 3 discusses these activities in detail.
Other activities involve program management and surveillance. General guidance for these
activities is given in the remaining sections of this chapter. Criteria for determining
abatement project completion are discussed in Chapter 4.
2.3 Obtaining Advice
In developing and implementing the program plan, the program manager should identify
persons within the school system or affiliated with the building owner who are familiar with
structural or operating characteristics of the building under consideration, or who have
specialized legal, medical, or communications expertise. Included among this group of
technical advisors are:
• school board or building architects;
• custodial staff supervisors;
• heating and ventilation engineers;
• loss control specialists (especially where catastrophic insurance is in force);
• the building owner's attorneys (and other legal specialists as needed);
• medical specialists; and
• public relations specialists.
Expert assistance in detecting the presence of asbestos, in assessing the need for corrective
measures, and in undertaking control actions may also be needed. This expertise may be
provided by a person already working with the building owner who has or can gain experience
in asbestos assessment and control, or by an outside consultant, such as an engineer,
industrial hygienist, or architect. The technical expert may be asked to participate in program
planning prior to determining if asbestos-containing materials are present. If the program
manager is confident about implementing the method offered in previous EPA guidance for
inspecting, sampling, and analyzing to detect asbestos (Lucas, et al 1980a and 1980b, and the
FEDERAL REGISTER [47 FR 23360]), then the assistance of the technical expert may be
postponed until it is determined that asbestos is present. In either case, the expert should be
prepared to participate in developing the control program plan.
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The expert also may be asked to assist in assessing the need for corrective action and in
selecting among remedial measures. If the selected control strategy requires an abatement
contractor, the expert could help select a contractor and could monitor contractor perfor-
mance. If this option is selected, the expert should have no affiliation with the abatement
contractor in order to avoid a possible conflict of interest.
Architects often are selected as technical experts because they are familiar with the legal and
technical aspects of building construction and contract administration. This knowledge is
valuable if an abatement contractor is ultimately employed. Many school boards have chosen
to delegate to the architect the entire responsibility for writing contract specifications,
monitoring work performance, and determining successful abatement (see Section 2.4 for a
discussion of abatement contracting). However, it must be noted that not all architects are
experienced in assessing asbestos problems or developing control plans. It thus may be
desirable to utilize other experienced advisors and experts to complement the architect.
Alternatively, asbestos experts or technical advisors may learn enough about contracting
procedures to take on the responsibilities of directing the abatement contractor.
Regardless of which option is selected for obtaining expert advice and assistance, the quality
of the service obtained is critical. If an outside consultant is hired, chances for obtaining high
quality services will be improved if the following suggestions are followed:*
• Require evidence of experience and/or training in assessing asbestos problems
and in asbestos control. Check references, especially other building owners for
whom the consultant has worked.
• Prepare a job description to include daily worksite inspections while an abatement
project is in progress. The technical expert should check for compliance with
contract specifications by the abatement contractor.
• Pay the consultant on a fixed price or simple time basis rather than a percentage of
total abatement project cost (as is common for architects). This would further
reduce concerns about conflict of interest.
As noted previously, the Regional Asbestos Coordinators are primary sources of information.!
Through their experience, they offer guidance on developing and managing asbestos control
programs. The RACs also can help identify technical consultants, laboratories for performing
asbestos analyses, firms to conduct abatement actions, and other building owners in their
region with experience in asbestos control. The RACs also may provide training for persons
involved in asbestos-related activities. An excellent example of a comprehensive asbestos
control training program is the one developed by EPA's Region IV Office in conjunction with
The Georgia Institute of Technology.
2.4 Implementing Corrective Measures
Once corrective measures have been selected, the program manager must decide on the
method of implementation. In general, two options are available: in-house staff or outside
abatement contractors. Where the corrective action is a set of special operations and
maintenance procedures designed to reduce and maintain low airborne fiber levels, the
*The American Institute of Architects' "Standard Form of Agreement Between Owner and Architect"
also may prove useful where an architect or other third party is primarily responsible for overseeing
abatement. A copy of this publication can be obtained from AIA, 1735 New York Avenue, Washington,
DC 20006.
t Addresses of the 10 RACs can be found in Appendix B.
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in-house custodial staff is likely to implement it.* If asbestos removal, enclosure, or
encapsulation is chosen as a control measure, it is extremely important to employ persons
trained or experienced in handling asbestos. Any effort to reduce asbestos exposure levels by
treating asbestos-containing material entails a hazard to abatement workers and building
occupants alike. Removal, enclosure, or encapsulation of this material may involve large-
scale release of fibers. Properly conducted by trained workers, these control activities can be
highly successful. But if these activities are undertaken by workers having no asbestos
experience, and without strict adherence to recommended operating procedures, the airborne
asbestos concentration levels experienced after abatement may rise above preabatement
levels.
When an abatement contractor is to be employed, the program manager (or the technical
expert) should consider taking the following steps to increase the likelihood of successful
asbestos abatement:
• Establish contract specifications tailored to individual projects;
• Conduct a thorough evaluation of contractors prior to contract award;
• Require persistent on-site surveillance of contractor performance during abate-
ment activities; and
• Establish criteria prior to the start of abatement work for determining successful
project completion.
EPA's guidance for treating asbestos in schools, published in 1979 (USEPA 1979, Sawyer and
Spooner 1979), provides a starting point for preparing project specifications. EPA and OSHA
regulations and recommended work practices for asbestos removal, enclosure, and encapsu-
lation are described briefly in those publications.
EPA's experience since 1979, primarily with school districts, has raised concerns about
adequate contractor performance. In several cases, an apparently competent contractor
prepared a responsive and price-attractive bid only to prove incapable of following or
unwilling to follow contract specifications after being awarded the contract. The following
suggestions are offered to help building owners avoid these situations and to increase the
likelihood of a successful project.
• Contractors should be required to show evidence of experience and/or training in
asbestos abatement. Check references and ask for names of other building
owners for whom contract bidders have worked.
• Rather than simply noting that the contractor is responsible for complying with all
EPA, OSHA, and state/local regulations, require prospective bidders to describe
their worker protection and site containment plans in detail. Ask for their standard
operating procedures and employee protection plans, with specific reference to
their OSHA medical monitoring and respirator training program. The information
obtained is extremely useful in distinguishing truly competent firms. An oral
discussion is recommended to further demonstrate the contractor's capabilities
and understanding of the problem.
• Insist on proof of adequate liability and property (builder's risk) insurance from all
prospective bidders. A performance bond should also be required of the contractor
before work begins.
• Ask for detailed written descriptions of how bidders will satisfy the project
specifications. Use these to judge the competence of bidders and, subsequently,
*Some school systems have trained a centralized cleanup team for periodic deployment in individual
school buildings.
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the quality of work. The technical expert should be actively involved in evaluating
bids. Information in Chapter 3 on specific problems with each abatement tech-
nique should be useful in evaluating bids.
• Be specific about what constitutes successful job completion. A thorough visual
inspection to ensure adequate cleaning is an absolute necessity; air monitoring
also should be considered (see Chapter 4 for a discussion on determining project
completion).
• Encourage active competition for abatement contracts. Wide variation in price
among contractors is the rule. Remember that successful abatement, not cost
minimization, is the goal. A premium may well be justified to help assure success.
These suggestions are based on the past few years of experience with asbestos abatement in
schools. Recall that the EPA Regional Asbestos Coordinator is available as a source of
additional information and suggestions. The RAC should be contacted early in the process of
developing a control plan.
2.5 Recordkeeping
Regardless of the corrective actions taken, the asbestos program manager should prepare
thorough and detailed records of all findings and abatement actions. These should be retained
in a permanent file. Information on the location and nature of any remaining asbestos-
containing materials is critical to protecting building occupants and to controlling these
materials during remodeling or building demolition.
EPA's Asbestos-in-Schools rule contains specific recordkeeping requirements. These include:
• the number and locations of samples used to determine if asbestos is present;
• a copy of the results of laboratory PLM analyses of the sampled material;
• the asbestos content of the material sampled in each area;
• a statement certifying that no friable asbestos-containing materials are present if
no friable materials are found or if the tests for asbestos are negative; and
• a description of each building, indicating the location(s) and approximate area(s) in
square feet of asbestos-containing materials.
In addition to information on the presence of asbestos-containing materials, the nature of
potential exposure problems should be characterized and the type of abatement actions taken
should be described. Specifically, this record might include:
• descriptions and photographs of the condition, accessibility, and other relevant
characteristics of asbestos-containing material found in various parts of the
building before corrective measures were taken (section 3.2 in Chapter 3 contains
a discussion of assessing asbestos-containing materials);
• detailed descriptions of asbestos removal, enclosure, encapsulation, or other
control measures applied to individual areas, including the date action was taken;
• ongoing efforts to monitor potential asbestos problems and employ special
operating and maintenance practices;
• names of technical advisors and all consultants and contractors hired for
asbestos-related work; and
• costs associated with all abatement actions.
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CHAPTER 3 — DETECTING ASBESTOS, ASSESSING THE PROBLEM,
AND SELECTING A COURSE OF ACTION
The central questions facing owners of buildings where the presence of asbestos is suspected
are: (1) Is asbestos actually present? (2) If it is, how significant are existing or poten-
tial exposure problems? and (3) What control measures are needed? This chapter dis-
cusses technical aspects of the process for addressing these questions that was outlined in
Chapter 2. The most significant conclusions and recommendations are summarized below.
Inspecting, Sampling, and Analyzing for Asbestos:
• Inspection and sampling procedures to detect friable asbestos-containing mate-
rials have been published in previous EPA documents. Key points are identifying
homogeneous sampling areas and implementing the recommended quality assur-
ance plan during sampling and analysis.
• Although emphasis is on detecting friable materials, the .possible presence of
nonfriable asbestos-containing materials must also be considered. However, non-
friable materials should not be sampled since sampling may unnecessarily release
fibers.
Assessing the Need for Corrective Action:
• The condition of asbestos-containing materials and their potential for disturbance
or erosion can be used to determine if corrective measures should be taken.
• Factors for assessing material condition and the potential for disburbance or
erosion should be used qualitatively. Numerical scoring and index systems have
not proven reliable.
• Due to technical problems and high costs, monitoring of airborne asbestos is not
recommended for assessment purposes.
Control Techniques:
• Four alternative control actions should be considered: (1) asbestos removal,
disposal, and replacement; (2) enclosure; (3) encapsulation; and (4) a special
operations, maintenance, and reinspection program.
• The applicability and cost of each alternative will depend on the amount and
condition of the asbestos-containing materials to be treated and structural
characteristics of the underlying supporting surfaces.
• All control measures except the special operations and maintenance program
should be undertaken only with proper work area containment and worker
protection. Protection for maintenance workers also may be necessary.
• Until a control alternative is chosen, interim operations and maintenance pro-
cedures should be used to reduce levels of airborne fibers.
• A continuing program of special operations and periodic reassessment will be
necessary even after asbestos-containing materials have been enclosed or
encapsulated.
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Decision-Making:
• It is difficult to develop a set of rules that can be uniformly applied to every
asbestos control situation. Local conditions make each situation unique. However,
organizing and analyzing information on (1) the condition and potential for dis-
turbing the asbestos-containing materials, and (2) the advantages and disadvan-
tages of control alternatives will help in selecting an effective course of action.
3.1 Inspecting, Sampling, and Analyzing for Asbestos
As discussed in Chapter 2, the first task in an asbestos control plan is to determine whether or
not asbestos is present. This involves investigating building records for mention of asbestos-
containing materials, inspecting the building for friable materials, and analyzing samples of
friable material for asbestos. Figure 4 illustrates a logical sequence of steps for this task. First,
investigate building plans, remodeling records, and other sources (such as personal
knowledge) for specification of asbestos-containing materials. Information on the type and
location of asbestos-containing materials will help focus the next step—inspecting for friable
materials in the building. A building inspection might start with those areas where asbestos-
containing materials are reported to be present and then expand to all parts of the building. If
friable materials are found, they should be sampled and analyzed as discussed below.* If the
presence of asbestos in the friable materials is confirmed (more than 1 percent by weight),
then the assessment for corrective action is begun. If, on the other hand, no friable materials
are found—or if they are found, but do not contain asbestos—document these results. A
formal statement of these findings (called "negative certification" in Figure 4) is required for
schools. If the investigation of building records or the building inspection indicates that
nonfriable asbestos-containing materials are present, these materials should be reinspected
periodically for changes in their condition.f Reinspection is especially important for friable
materials that have been painted or covered with a hard wrapping (and would thus be
classified "nonfriable"), such as pipe and boiler insulation. Damage or slow deterioration of
the wrapping or paint could cause significant release of asbestos fibers, thus requiring a
detailed assessment of the need for corrective action.
To further clarify the types of materials to be investigated in an asbestos control program, a
chart showing asbestos-containing materials found in buildings is presented in Figure 5. The
first level is based on the most important characteristic—friability. Materials which are friable
and contain asbestos are likely to be sprayed or troweled onto surfaces in either fibrous or
cementitious form. Nonfriable asbestos-containing materials are more diverse. As noted
above, asbestos insulation on pipes and boilers is of special concern. Pipes and boilers are
usually accessible to building occupants (especially custodial workers) and often are prone to
damage. Pipe and boiler insulation may look like chalk, bricks, mud, or corrugated cardboard.
Often these insulation materials are enclosed in a canvas, stainless steel, or plastic jacket.
The boiler wrapping and pipe jackets should be carefully inspected for damage that could
allow release of asbestos fibers. Other nonfriable asbestos-containing materials normally are
hazardous only when cut, drilled, sanded, or removed during remodeling or demolition. Note,
again, that nonfriable pipe and boiler insulation should be considered friable when damaged.
Examples of friable and nonfriable asbestos-containing materials were shown in Figure 3.
Figure 13 shows pictures of damaged and deteriorating pipe insulation.
*The Asbestos-in-Schools rule allows schools to skip the sampling and analysis steps and simply
assume that any friable materials found in the building contain asbestos. The location of all friable
materials must be documented and all affected parties, as described previously, must be notified.
t Inspection for nonfriable materials is not required by the Asbestos-in-Schools rule.
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Figure 4. Steps in investigating for the presence of asbestos.
I Investigate building records I
Inspect for friable
materials
re friabl
materials
resent?
Document findings,
reinspect periodically,
schools prepare
negative certification*
Is there
evidence of
nonfriable asbestos-
containing materials?
Sample and
analyze for
asbestos
Document findings,
schools prepare
negative certification
Is
asbestos
present?
Proceed with
next phase of
assessment
*Negative certification is a statement certifying that no friable asbestos is present.
3-3
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Specific requirements for sampling and analysis in schools were given in the Asbestos-in-
Schools rule (40 CFR Part 763, Subpart F). Although legal requirements for investigating the
presence of asbestos apply only to schools, the procedures are broadly applicable to any
building. A detailed sampling and analysis plan must be developed and implemented. Quality
assurance procedures must be employed for reliable results. A recommended approach is
described in the Asbestos-in-Schools rule and in "Asbestos-Containing Materials in School
Buildings: Guidance for Asbestos Analytical Programs" (Lucas, et al 1980a). Key elements
are provided here to help the reader understand sampling and analyzing bulk material for
asbestos. (Further information on sampling and analysis is available by calling the EPA
Technical Information Service, (800) 334-8571, or the Regional Asbestos Coordinators.)
• Appoint a sampling and analysis coordinator to oversee the entire sampling and
analysis operation and quality assurance program. The asbestos program manager
typically assumes this role.
• Identify homogeneous sampling areas of friable material. These are areas covered
with material that has the same appearance and texture. If an area that appears
homogeneous is known to consist of different materials, perhaps due to remodel-
ing or building expansion, the area should be subdivided for sampling purposes.
Damaged or exposed parts of pipe and boiler insulation should also be considered
distinct "sampling areas."
• Collect at least three core samples of material in each homogeneous sampling
area. The method of random selection should be used to identify locations where
samples will be taken. Random selection will assure an established statistical
level of confidence in the estimates of asbestos content. (Specific procedures for
designing the sampling plan are given in the EPA guidance document referenced
above [Lucas, et al 1980a] and in a companion document [Lucas, et al 1980b].)
Note that pipe and boiler insulation in good condition should not be sampled, since
sampling requires breaking the insulation jacket.
• Develop a quality assurance program following recommendations in the guidance
document (Lucas, et al 1980a). A key feature is the use of split samples, that is,
duplicate samples from the same sampling location, to confirm laboratory
analyses.
• Submit samples to a qualified laboratory for analysis. A list of laboratories that
participated in the EPA quality assurance program for bulk sample analysis
appears in the document noted above (Lucas, et al 1980a). The list is periodically
updated. A current list and additional information on laboratory qualifications may
be obtained by calling the EPA Technical Information Service, (800) 334-8571, or
the RACs. The approved method of bulk sample analysis for asbestos is polarized
light microscopy. A supplementary method, X-ray diffraction, may be required in
certain cases. The laboratory report should include:
(1) sample identification number;
(2) analytical method used;
(3) sample appearance and treatment;
(4) type and percent of both asbestos and nonasbestos constituents;
(5) method of quantification; and
(6) analyst's name.
The type of asbestos mineral present may be important information when the
asbestos-containing material is eventually removed.
• To determine whether the samples have more than 1 percent asbestos, the
laboratory results should be interpreted using statistical procedures described in
previous EPA guidance (Lucas, et al 1980a).
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3.2 Assessing the Potential for Exposure to Asbestos
If the sampling and analysis of bulk material show that asbestos is not present, there is no
need for further action except to document the findings. A positive finding indicates the need
for a thorough assessment of the potential for exposure to airborne asbestos, followed by the
consideration of appropriate corrective measures. This section addresses various approaches
to assessing the need for corrective action.
3.2.1 Principles of Fiber Release, Suspension, and Transport
As noted in the previous section, asbestos fibers can be released spontaneously from
asbestos-containing material in the normal process of the material's aging and deterioration.
This process can be accelerated by air movement or vibration. In addition, a dramatic increase
in the rate of fiber release may accompany disturbance of asbestos-containing material. Once
released, either by deterioration or by sudden damage, asbestos may remain airborne for
extended periods of time. The small size of asbestos fibers facilitates their suspension by
regularly fluctuating air currents. Even when the fibers eventually settle during quiet periods
(for example, weekends), they are readily re-suspended by the normal activities of building
occupants and custodial and maintenance personnel.
Asbestos fibers are transported from the point of release to other locations within the building
largely via airstreams from air circulation equipment. Measurements of asbestos concentra-
tions in school buildings suggest that fiber levels can be elevated throughout a building even
though the area of fiber release is restricted to a few rooms (Constant, et al 1982).
3.2.2 Estimating the Potential for Fiber Release
One approach to assessing the need for corrective action is to estimate the likelihood of fiber
release from materials in which asbestos has been confirmed. This approach uses subjective
assessments of asbestos-containing materials, and assumes relationships between airborne
asbestos levels and characteristics of these materials. The approach has the advantage of
practicality and, in certain circumstances, may reveal the potential for future fiber release
even when actual levels of airborne asbestos are relatively low.
The following sections discuss the use of various factors to assess characteristics of
asbestos-containing materials. Their use both as qualitative descriptors and in numerical
rating schemes is evaluated.
3.2.2.1 Proposed Exposure Indices
Several lists of assessment factors have been proposed for the purpose of estimating the
potential for fiber release from asbestos-containing materials. These include the EPA factors
as presented in Chapter 7, Part 1, of the initial EPA guidance document (USEPA 1979a), the
U.S. Navy's asbestos risk evaluation procedure (Lory 1980), the Toronto Board of Education
index* (Pinchin 1982), and the U.S. Department of Education's asbestos scoring system as
published in the FEDERAL REGISTER (46 FR 4536). Each list contains factors relating to the
current condition of the material, the amount of asbestos present, and the vulnerability of the
material to physical damage and erosion by air movement. Guidance is provided for scoring
*This is also known as the "modified Ferris Index."
3-6
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each factor and combining those scores into an overall index.* In this way, asbestos-
containing materials in various locations within a single building or in different buildings can
be evaluated and compared. The value of these indices rests on the validity of the assumed
relationships between factor scores and actual (or potential) concentrations of asbestos in the
air.
Several tests of these relationships have been conducted. The EPA-sponsored study of an
urban school district (Constant, et al 1982) is the most recent and comprehensive. Of the
various EPA factors which were assumed to be positively correlated with measured levels of
airborne asbestos, only two were confirmed: the presence of water damage and the proximity
of the material to an airstream created by the ventilation system. For several factors (degree of
friability, percent asbestos content, degree of activity), a direct relationship with airborne
asbestos was not confirmed. Other factors (accessibility, degree of exposed surface area,
condition of the material) did not receive a fair test, typically because little or no variation in
scores was observed in the schools. Tests conducted by other investigators (Sebastien, et al
1982 and Pinchin 1982) using combined factor scores (that is, the index values) likewise
produced little correspondence between ratings and measured air levels. Tests using the U.S.
Navy risk procedure index and the Toronto Board of Education index fared no better (Pinchin
1982).
These findings indicate that numerical ratings derived from subjective assessments of fiber
release potential are not reliable indicators of measured airborne asbestos levels. However,
selected assessment factors may help identify a high potential for future fiber release.
Employed in a qualitative manner, some factors also may help distinguish among major
categories of asbestos problems. Selection and use of these factors is discussed in the
following section.
3.2.2.2 Usefulness of Individual Assessment Factors
The results of the hazard index evaluation studies emphasize the complexity of the fiber
release process. Some proposed factors focus on conditions which are necessary but not
sufficient for fiber release. A few relate to the probability of release given other necessary
conditions, and thus gauge future rather than current problems. Others refer to similar or
highly correlated features of asbestos-containing materials and should be combined. As a
result, the use of the EPA factors to assess potential fiber release has been re-evaluated.
Table 1 displays the assessment factors judged most useful as a result of this re-evaluation.
The first three individual factors focus on the current condition of the asbestos-containing
material. If water damage, physical damage, slow deterioration, or delamination of the
material is evident, then fiber release has occurred, is occurring, or is likely to occur in the
future. Evidence is obtained from the appearance of the material and from the presence of
broken or crumbled material on the floor, tables, or other horizontal surfaces. Factors under
the second heading reflect the potential for fiber release due to disturbance or erosion.
Exposed and highly accessible materials in areas frequented by building occupants or subject
to maintenance activities are more vulnerable to physical damage than materials in other
locations. In this category are materials subject to vibration from mechanical equipment,
sound, or athletic activities. Examples include materials near a gymnasium or band room, or
materials in buildings near an airport or highway. Likewise, asbestos-containing materials
* Although the EPA guidance document (USEPA 1979a) does not describe scoring procedures, a
scoring routine known as the EPA "algorithm" was developed and appeared in the advance notice of
proposed rulemaking for the Asbestos-in-Schools rule published in the FEDERAL REGISTER (44 FR
54676).
3-7
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Table 1. Organization of Factors for Assessing Fiber Release Potential
Condition of asbestos-containing material
• Evidence of deterioration or delammation from the underlying surface (substrate)
• Evidence of physical damage
• Evidence of water damage
Potential for disturbance or erosion
Proximity to air plenum or direct airstream
Exposure (i.e., is it visible), accessibility (to building occupants and maintenance personnel), and the
degree of activity (air movement, vibration, movement of building occupants)
Change in building use
located in an air plenum or near a forced airstream are likely to suffer surface erosion. In
addition, fibers released into an airstream may be transported to other parts of the building,
possibly increasing the number of people exposed. A change in building use may cause
changes in several of the other factors. Figures 6 and 7 illustrate several characteristics of
asbestos-containing materials addressed by these factors.
Friability and asbestos content are two factors discussed in the initial EPA guidance
document (USEPA 1979) that do not appear in Table 1. Friability has already been discussed
in the context of inspecting for asbestos-containing material (Chapter 2). Since only material
determined to be friable needs to be sampled and analyzed, using friability for assessment at
this stage would be redundant. Asbestos content may still be important in some situations,
but this factor proved highly unreliable as an indicator of airborne asbestos concentration in
the previously mentioned EPA validation study (Constant, et al 1982). Substantial fiber
release apparently can occur in damaged or deteriorating materials, even where asbestos
content is low.
Detailed descriptions of each factor in Table 1 are given in Appendix D. The information there
should assist the evaluator in judging the condition and exposure or disturbance potential of
individual sites.
The interpretation of information from an assessment of fiber release and its use to reach
decisions on abatement strategies is discussed in the last section of this chapter (Section 3.4).
The factors in Table 1 are expressed in a way which fosters a "yes" or "no" type of response.
The use of "yes" and "no" responses eliminates the need to rate and score each factor and
provides a less ambiguous basis for decision-making.
3.2.3 Measuring Airborne Asbestos
Another proposed approach to assessing the need for corrective action is to measure asbestos
fibers in the air. At best, this approach provides information only on current asbestos
3-8
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Delamination from a beam
Physical damage to ceiling material from a flagpole
*:,', v^*'**^
• **-y»sF-"/> .*" ^rs*->-4'4
^,«» « "Vfr-rt *'< - * *.• ^***»,'«»
Airstream erosion from a heating vent
High activity level near friable asbestos
Figure 6. Example assessment characteristics of asbestos-containing materials.
3-9
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Ceiling of a gymnasium in an elementary school
(no basketball marks)
Ceiling of a gymnasium in a high school showing evidence of
damage from basketballs thrown by students
Figure 7. An example of the effect of a change in building use.
3-10
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contamination and no information about the potential for fiber release and future air levels.
Moreover, the use of air monitoring as an assessment tool involves substantial technical and
economic problems which limit its use even for determining current levels of contamination.
As noted in Chapter 1, a list of procedures (protocol) for measuring asbestos in industrial
settings has been developed by the National Institute for Occupational Safety and Health
(NIOSH) in connection with the OSHA asbestos exposure standard. The NIOSH protocol
employs phase contrast microscopy (PCM) for asbestos measurement. The major short-
comings of PCM are that it cannot distinguish between asbestos and nonasbestos fibers or
resolve fibers with diameters less than 0.3 micrometers.* In addition, the NIOSH measure-
ment protocol is not designed to count fibers shorter than 5 micrometers. Many airborne
fibers in buildings with asbestos-containing materials are likely to have dimensions which fall
outside these limits. In addition, fibers from carpets, clothing, hair, paper, books, and many
other sources are likely to be present. As a result, PCM analyses of air inside these buildings
could be highly misleading.
Methods for measuring small as well as large fibers and for distinguishing asbestos from
nonasbestos fibers have been developed and used in various research studies. They use
electron microscopy (EM) (specifically, transmission electron microscopy) to measure fibers,
and both chemical and crystallographic analyses to identify asbestos minerals.f Air sampling
procedures involve sampling at several sites for extended periods and, frequently, collecting
several samples at each site. EPA has used these sampling procedures and EM under
experimental conditions to establish baseline asbestos levels in various indoor and outdoor
settings, and, as discussed above, to validate subjective rating approaches to assessing fiber
release. Technical bulletins will be issued by EPA as air sampling and EM protocols are
refined. Even then, the difficulty of sampling in occupied buildings and the number of samples
needed to detect peak as well as prevalent airborne levels may preclude the use of air
monitoring for routine assessment. The cost of EM analysis is high (about $500 per sample),
and few laboratories are qualified to perform it. Given these limitations, EPA does not
recommend the use of air monitoring for assessment purposes at this time.
3.3 Asbestos Control Measures
Developing and implementing an effective strategy to correct asbestos exposure problems
requires detailed information on the applicability and relative costs of alternative control
measures. New information on these subjects is presented in this section for each of the four
generic approaches to asbestos control: (1) material removal, (2) material enclosure, (3)
material encapsulation, and (4) special operations and maintenance practices combined with
periodic reassessment of asbestos-containing materials. These approaches are applicable
both to material sprayed or troweled on surfaces and to pipe and boiler insulation. However,
control problems created by the two categories of asbestos-containing materials are different
enough to warrant separate treatment here.
3.3.1 Control Alternatives for Material Sprayed or Troweled on Surfaces
Although each of the four approaches to asbestos control is a distinct alternative, they share
several features. The first is the need to conduct a detailed inspection of both the asbestos-
containing material to be treated and the underlying surface. Such an inspection should be
*A micrometer is one-millionth of a meter. See Appendix A for a simple discussion of measurement
units used to describe and measure asbestos fibers.
fA provisional protocol for EM measurement of asbestos has been developed by EPA (Samudra et at
1977).
3-11
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undertaken for each separate homogeneous area of asbestos-containing material, usually a
single room, hallway, or central space. (Recall the cautions noted previously about the
possibility of seemingly homogeneous areas being composed of different materials and thus
requiring separate inspection.) It is especially important to inspect above a suspended ceiling
with lay-in panels since this may reveal otherwise hidden material (see Figure 8).
The following information should be collected:
• size of the area, since this will affect the cost of asbestos control;
• type of ceiling construction if the ceiling is coated (for example, concrete joist and
beam, concrete waffle slab, steel beam or bar joist, suspended metal lath,
suspended lay-in panels, tile, metal, corrugated steel), since different construction
types present different control problems;
• ceiling height, which may determine the practicality of enclosing the material;
• type of wall (for example, smooth or rough concrete, block or brick, plasterboard),
which may indicate whether an encapsulant is needed if the material is removed;
• thickness of asbestos-containing material and variation in thickness, since encap-
sulants should not be applied to thick material.
Photographs also may be desirable for documenting the current condition of asbestos-
containing material. A building evaluation form developed by EPA's Region VII Office is
included in Appendix E for illustrative purposes.
A second common feature of the four approaches to asbestos control is the need for worker
protection during control activities. Worker protection depends on the strict use of NIOSH-
approved respirators. The OSHA standards specify the use of three different respirators,
depending on the expected concentration of fibers in the work area: a half-face mask with
either a single-use or replaceable filter, a full-face mask with replaceable filter and a pump to
assist breathing, and a full-face mask with a self-contained or remote air supply. NIOSH now
recommends that the first type of respirator not be used, because it does not seal properly
around the face, nor has it (or any other type) been tested for effectiveness specifically against
asbestos fibers.* Supplied air (type "C") units offer the most protection. Respirators are
required for asbestos removal. They are highly recommended for the other control measures,
since enclosure and encapsulation activities may produce fiber levels as high as or higher
than those created during asbestos removal.
A third common feature is that an aggressive program of interim control should be instituted
once the level of exposure or exposure potential has been assessed and before a permanent
control program begins. Consider the following program measures:
• Carpets should be steam cleaned or vacuumed with a high efficiency particulate
air (HEPA)-filtered vacuum cleaner.
• Contaminated books and furniture should be cleaned with HEPA-equipped vacuum
cleaners, or dusted in the manner described below.
• Dusting and mopping should be done with wet or damp cloths and mops. These
should be discarded in sealed plastic bags according to EPA regulations for
asbestos removal and disposal. Workers should be encouraged to wear a respirator
as a precautionary measure.
*A letter setting forth NIOSH's concerns about these respirators was sent to respirator manufacturers
on August 25, 1980. A copy of this letter appeared in the December 1980 issue of the Journal of the
American Industrial Hygiene Association.
3-12
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Figure 8. Asbestos-containing material located above a suspended ceiling
3-13
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• When filters in a central air ventilation system are replaced, they should be treated
as asbestos-contaminated waste. That is, they should be sprayed with a light
water mist before removal and then sealed in plastic bags for disposal.
• Building occupants and maintenance workers should be cautioned about further
damaging the asbestos-containing materials (for example, by hanging plants or
mobiles from the ceiling, rewiring electrical circuits, or installing new fixtures).
• Maintenance people should be warned about disturbing suspended ceilings or
other areas where fibers collect. They should also be told not to patch or repair
damaged material before assessment of alternative abatement techniques.
Fourth, proper work area containment is highly recommended for all abatement techniques
except special operating and maintenance practices. Once abatement work begins, all
uninvolved persons should be kept out of the area. Containment typically means construction
of barriers with 6 mil polyethylene plastic sheets joined with folded seams, and with sealing
tape at the seams and boundaries. Some contractors have experienced problems in securing
plastic sheets to walls. Thinner sheets or a better attachment system (for example, stapling
and taping sheets to furring strips fastened to walls) may be required. (Figure 9 shows the
construction of a typical containment system.) Air locks and worker decontamination facilities
with showers are recommended.* So, too, are negative air pressure systems, as described in
Section 3.3.1.1 below. Without adequate containment, increased exposure for building
occupants is likely. Abatement activities should be conducted during vacations or other times
when few people are in the building.
Detailed descriptions of work area containment and worker protection can be found in Part 1
(Chapter 9) and Part 2 (Section 2, Part II) of the initial EPA guidance on asbestos in schools
(USEPA 1979, Sawyer and Spooner 1979). The above comments are reminders of general
requirements. They also update previous guidance on respirators and the need for work area
containment in enclosure and encapsulation operations. Technical bulletins on work area
containment will be published in the future.
Regardless of the abatement measure selected, a rigorous post-project cleanup is necessary.
This should include wet mopping of all horizontal and vertical surfaces in the work area.
(Again, wet mopheads and cloths should be discarded in sealed plastic bags and treated as
asbestos-contaminated waste.) Cleaning of surfaces outside the work area is highly recom-
mended as a precautionary measure. Two cleanings—the second after suspended fibers have
settled over several days—will provide better assurance of fiber reduction than a single
cleaning.
3.3.1.1 Removal, Disposal, and Replacement
Many asbestos abatement experts believe removal of asbestos-containing material is the only
final and satisfactory solution to the problem of asbestos exposure. Competently performed,
with adequate protection for workers and building occupants, removal can eliminate all
potential for exposure. On the other hand, removal may be more complicated and cost more
initially (although not necessarily in the long run) than other abatement measures.
The general approach to removal of asbestos-containing material was presented in the initial
EPA guidance documents, Chapter 8 of Part 1 and Section 4, Part II of Part 2 (USEPA 1979,
Sawyer and Spooner 1979). (Figure 10 is a photograph of a typical removal project.) Key
features outlined in the EPA documents include:
*OSHA decontamination requirements specify worker change rooms as a minimum provision for
asbestos removal projects.
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Figure 9. Construction of containment barriers.
3-15
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Figure 10. An asbestos removal project.
3-16
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• Removal of all types of asbestos except amosite must be initiated only after the
material is treated with a solution of water and a wetting agent to reduce fiber
release. Some types of amosite-containing materials will not adsorb either water
or water amended with the wetting agent suggested by EPA (50% polyoxyethylene
ester and 50% polyoxyethylene ether) in Part 1 of the initial guidance document
(USEPA 1979). Wetting agents should be tested on the material for adsorption. If
the material won't adsorb the wetting agent, a dry removal will have to be
undertaken using Type C respiratory protection for the workers. EPA must approve
all dry removal operations.
• Friable asbestos-containing material must be disposed of in "leak-tight con-
tainers," typically 6 mil polyethylene bags. Bags frequently are placed in 55-gallon
drums for additional protection.
• OSHA procedures for worker protection and decontamination, as well as for
measurement of airborne asbestos, must be strictly followed. While not required
by law, EPA procedures for work area containment are likewise a prerequisite for
safe removal operations (see Chapter 9 and Appendices A and B, Part I of previous
EPA guidance [USEPA 1979]).
Research on asbestos removal plus EPA's experience with removal activities in schools since
1979 have pointed up several issues that require more attention when removal is the chosen
course of action.
• Surveillance of work practices at the worksite by a representative of the building
owner is absolutely necessary. Like any other rapidly growing industry, asbestos
removal has attracted companies with varying experience and competence. Even
reputable firms sometimes subcontract work to expedite jobs. Relaxed enforce-
ment of rules and incomplete adherence to contract specifications occur all too
frequently. A worksite supervisor representing the building owner, and with
authority to stop removal activities whenever circumstances dictate, should be
present at all times. The program manager's technical expert is a logical choice for
this role.
• A breach in the containment barrier is a significant exposure hazard for building
occupants and should be repaired immediately. Using negative pressure systems
together with HEPA filtration (that is, low volume exhaust fans with HEPA filters)
to move air from within the work area to outside the building may give some
protection in the event of a breach. Appendix F contains a summary of specifica-
tions for negative air systems.
• Another problem observed at several worksites concerns dismantling of contain-
ment barriers at the end of the removal operation. Sealing tape used to attach the
plastic sheets to walls and ceilings frequently cannot be removed without peeling
paint from these surfaces. It may be wise to include the cost of repainting all walls
(and ceilings, if appropriate) in estimates of asbestos removal costs.
• Disposal and transport of removed material has been a problem. Containers full of
wet material are very heavy and difficult to transport. Spilled material both in and
outside the work area has been observed. Care must be exercised in sealing and
handling these containers. Disposal sites may be difficult to locate. Some states
require a disposal permit before removal begins.
• Amended water (water with wetting agents) from spray operations may leak
through the polyethylene sheets and damage floors, especially tile and wood. A
cost-effective solution might be double plastic sheets carefully sealed.
3-17
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Once removal and disposal operations are finished, the need to apply a sealant on the
exposed surface must be evaluated. This is also the time to decide whether to reinsulate or
resoundproof with asbestos-free materials. In general, sealants are necessary where the
underlying surfaces are porous (for example, concrete blocks or slabs), since a few fibers
usually remain after removal.
Cost of asbestos removal varies widely among regions and among specific jobs. For example,
the cost for both removal and disposal ranges from $2 to $13 per square foot (USEPA 1980).*
Sealant and insulation replacement costs are additional.
3.3.1.2 Enclosure
As the term implies, enclosure involves construction of airtight walls and ceilings around
surfaces coated with asbestos-containing materials. Enclosures should be constructed with
impact-resistant materials. Since the asbestos-containing materials will have to be removed
when the building is remodeled or demolished, enclosure is only a temporary solution. On the
other hand, carefully constructed, airtight enclosures may reduce, if not eliminate, emission
of fibers within the building for its remaining life.f
Figure 11 shows a typical enclosure project. The following observations supplement the
discussion in Part 2 (Section 3, Part II) of initial EPA guidance (Sawyer and Spooner 1979) on
enclosures:
• As noted above, OSHA regulations and EPA recommendations for protecting
workers and building occupants are not binding for enclosure activities. But using
respirators and containment barriers is certainly a good idea. Installing an
enclosure will probably mean drilling and anchoring into dry asbestos-covered
surfaces. This releases dry asbestos fibers and could raise airborne asbestos
concentrations to highly dangerous levels. Drills equipped with HEPA vacuum
filters will reduce fiber release.
• Underlying structures must be able to support new walls and ceilings.
• New construction material should be impact-resistant and assembled to be
airtight. Gypsum panels taped at the seams, tongue and groove boards, and
boards with spline joints all qualify. Suspended ceilings with lay-in panels do not.
Joints between walls and ceilings should be caulked.
• If lights are recessed into asbestos-containing material, they must be removed
carefully to minimize the release of fibers. Lights should be reinstalled in or
beneath the new ceiling.
• Plumbing lines and computer cables may have to be relocated.
• Building records must note the presence of asbestos behind the enclosure to
prevent accidental fiber release during remodeling and building demolition.
Cautionary signs placed on the enclosure may be a good idea.
When appropriate worker protection and worksite containment measures are employed, the
initial cost of constructing enclosures is close to that of asbestos removal and disposal. Since
sealing the substrate and replacing asbestos-containing material are not required, total
project cost for enclosure initially may be somewhat lower. But the cost of periodic
inspections and repair of enclosures for the life of the building, and of asbestos removal
before demolition, may eliminate this cost saving in the long run.
*This cost range also reflects the experience of several Regional Asbestos Coordinators.
fNo enclosure will be literally airtight. The building practices recommended here are designed to
greatly reduce air movement across the enclosure boundary.
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Before enclosure
After enclosure
Figure 11. An asbestos enclosure project.
3-19
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3.3.1.3 Encapsulation with Sealants
Encapsulation involves spraying asbestos-containing material with a sealant. Ideally, this
activity helps bind together the asbestos fibers and other material components and offers
some resistance to impact damage. As with enclosures, encapsulants are, at best, a
temporary control measure. The asbestos-containing materials will still have to be removed
before building demolition. In addition, the presence of encapsulants can make wetting and
thus removing the material more difficult. Figure 12 shows an asbestos encapsulation
project.
Basic information on selecting and applying sealants was given in Parts I (Chapter 8) and 2
(Chapter 3, Part II) of EPA's initial guidance (USEPA 1979, Sawyer and Spooner 1979).
Encapsulation can be used on granular, cementitious material—commonly known as acous-
tical plaster. A sealant should penetrate the asbestos-containing material and adhere to the
substrate (or form a tough skin over the material), withstand moderate impact, be flexible and
flame retardant, resist deterioration over time, and be nontoxic. EPA recently sponsored an
evaluation of over 100 sealants using five criteria: impact resistance, flame spread, smoke
generation, toxic gas release during combustion, and adhesive/cohesive strength (USEPA
1981). The American Society of Testing and Materials (ASTM) also is developing laboratory
testing criteria for sealants. Additional information on the EPA sealant study can be obtained
from EPA's Office of Toxic Substances, Industry Assistance Office, (800) 334-8571.
Although the EPA study can help building owners choose a sealant, each sealant being
considered should be tested on site. In this way, its effectiveness on the materials under
consideration can be seen. Testing should be done over several days. The ASTM activity noted
above will include criteria and procedures for field as well as laboratory tests. Material that is
deteriorated or delaminated, or that shows extensive damage, should not be encapsulated. If
delaminated, the additional weight will pull it down; if deteriorated, it may be blown off by
application of sealant; if extensively damaged, it may be subject to repeated abuse and the
sealant will not hold up. The condition of the sealant on previously encapsulated materials
also should be inspected. Reapplication of sealant may be necessary.
Latex paint also has been used as a sealant. Its applicability is likewise limited to granular,
cementitious materials. If latex paint is to be used, a brand with a high vehicle content (at
least 60 percent by weight) and at least 25 percent (by weight) vehicle resin solids should be
selected. For the purpose of encapsulating asbestos-containing material, paint should be
applied considerably thicker than recommended for painting purposes. Experience suggests
that coverage should be no more than 100 square feet per gallon.
Sealants should be applied with airless spray equipment. One recommended method is to
apply a light (mist) coat, then a full coat applied at a 90 degree angle to the direction of the
first. Latex paint can also be applied by roller following the application of the mist coat before
it dries.
Encapsulation may be as costly as removal and disposal. This is largely due to the need for
work area containment and worker protection measures during sealant application.* As with
enclosure, no additional costs to replace asbestos-containing material are necessary. How-
ever, long-run costs are likely to be more than for removal due to (1) continuing inspection, (2)
periodic reapplication of sealant, and (3) removal of asbestos-containing material before
building demolition. (Encapsulation may make eventual removal more costly and hazardous
since the material will probably need to be removed in dry form.)
*The use of respirators is recommended for the application of any sealant. Solvent-based (as compared
to water-based) sealants may require the use of a supplied air (Type C) respirator due to hazards from
the solvent.
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Figure 12. An asbestos encapsulation project.
3-21
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Accurate, detailed records on the type of sealant used and the nature of the material and
substrate encapsulated are critical. This information is needed to avoid unintentional release
of fibers during remodeling or demolition.
3.3.1.4 Special Operations and Maintenance Procedures and Periodic Reassessment
An active program of building cleanup followed by proper maintenance and periodic
reassessment of the need for other control measures seerns to be appropriate where the
asbestos-containing material is in good condition and has a low potential for disturbance or
erosion. Other control measures will depend on the results of future reassessments. (In the
past, this option has been called "deferred action.") It minimizes current costs while providing
reasonable assurance of protection to building occupants.
Components of an initial cleanup program are the same as those of the interim control
program described in the introduction to Section 3.3.1. Fibers are removed from carpets,
floors, and all other horizontal surfaces. Building occupants and maintenance personnel are
cautioned about damage to asbestos-containing materials.
All custodial and maintenance personnel should be instructed in special operations pro-
cedures. They should be cautioned about removing suspended ceiling panels, installing
lighting or plumbing fixtures, repairing air handling systems, or, in general, engaging in any
activity that might damage asbestos-containing material or resuspend fibers. Building
occupants should be warned not to disturb the material by such acts as hanging plants from
asbestos-covered ceilings and damaging walls with furniture.
Periodic reassessments should focus on the condition of the asbestos-containing materials,
changes in building use, and changes in occupants' activity patterns. If reassessment
suggests that fiber release has occurred or is likely, then other corrective actions should be
formally evaluated.
3.3.2 Control Measures for Pipe and Boiler Insulation
Controlling asbestos-containing materials used to insulate pipes and boilers is different but
not necessarily more difficult than controlling asbestos-sprayed or -troweled surfaces.
Asbestos-containing pipe insulation takes many forms, including chalky mixtures of magnesia
and asbestos, preformed fibrous asbestos wrapping, asbestos fiber felt, corrugated paper, and
insulating cement. In most cases, the insulating material is covered with a protective jacket
(lagging) made of cloth, tape, paper, metal, or cement. (Figure 13 is a photograph of
deteriorated and damaged pipe insulation.) Boiler insulation may consist of thermal bricks
(refractory) or asbestos insulating blankets, but is usually covered with a finishing cement.
Occasionally, asbestos millboard is used as outside lagging on removable insulating covers
for stiffness. Lagging on pipes and boilers prevents spontaneous fiber release and helps
protect against disturbance. Damage from physical impact or water exfiltration is relatively
easy to observe and repair. On the other hand, not all parts of steam or hot water distribution
networks are readily accessible, and the high temperatures (if the steam cannot be shut off)
can make abatement an arduous task.
Where damage to pipe covering or boiler lagging is limited, the most straightforward approach
to abatement is repair. Duct tape can be used to seal open joints, and plastering with
nonasbestos material can restore large damaged areas or areas around valves and flanges to
their original condition. Where large portions of material must be removed, however, one
should use the same protective measures taken in the removal of materials sprayed or
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Figure 13. Pipe insulation in damaged and deteriorated condition
3-23
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troweled onto surfaces. That is, containment barriers should be erected and the full range of
worker protection devices must be employed. Containment bags with sealed holes for hand
access are alternatives to full room or full work area containment. As shown in Figure 14,
these bags are positioned around the pipe insulation to be removed and sealed to the pipe
with tape. Armholes and an inside pouch for tools let the worker remove insulation without
exposure to asbestos fibers. A sealed side port also can be constructed to allow access for
wetting the asbestos and evacuating the bag with a HEPA-filtered vacuum. These bags are
available commercially.
Figure 14. Custom containment bags for repairing or removing pipe insulation.
To remove individual pipe sections or an entire network, small sections, about an inch wide, of
insulation should be removed. The pipe then can be cut into manageable lengths with a torch.
At a minimum, exposed ends of the insulating material should be sealed with plastic and tape.
If the remaining insulation is not in good condition the entire pipe should be wrapped in 6 mil
plastic. More information on pipe and pipe insulation removal will be provided in a
forthcoming technical bulletin.
Disposal of insulation and lagging material must follow the same EPA procedures discussed
earlier and in Chapter 9 and Appendix A, Part I of the initial EPA guidance (USEPA 1979) for
asbestos waste.
3.4 The Decision-Making Process
Selecting a course of action for controlling asbestos-containing materials is a complicated
task. A large amount of complex information can be generated during the asbestos
assessment process. Evaluating and applying this information to the control alternatives may
be slow and difficult. Moreover, each building owner faces special circumstances involving
building use and conditions. Attempts to develop a set of definitive decision rules with broad
applicability are therefore of little value. However, using a systematic process for organizing
and interpreting relevant information has proven to be of considerable value. This section
outlines the key steps in such a process.
Figure 1 5 presents a sequence of questions which can be used to organize information and
guide decision-makers. Using the information available at each stage of an asbestos
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Figure 15. A guide to selecting a course of action.
Is
asbestos
present'
Are
materials
friable?
Material condition
Evidence of deterioration or
delammation from substrate'
Evidence of physical damage'
or
Evidence of water damage?
Potential for erosion or disturbance
Materials near an air plenum
or airstream'
Materials exposed, accessible'
or
Materials in an area of high activity
or subject to vibration'
Will planned changes in building
use affect the above factors'
Adopt special operations and
maintenance program, remspecl
materials periodically
(see Table 2)
Keep records, schools
prepare a negative
certification"
Keep records for remodeling
and demolition, reinspect
materials periodically
Remove, enclose, or encapsulate
material (see Table 2)
Remove, enclose, or
encapsulate material
(see Table 2}
*A statement certifying that friable asbestos-containing materials are not present.
3-25
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investigation, the decision-maker is guided toward groups of appropriate responses. In
essence, if friable asbestos-containing materials are present and determined to be (1) in bad
condition, or (2) subject to erosion or disturbance, then the material should be removed,
enclosed, or encapsulated. Only if the material is in good condition and unlikely to be
disturbed or eroded should a special operations, maintenance, and periodic reinspection
program be selected as the corrective action. If the asbestos-containing materials are
nonfriable, no corrective action is needed. Instead, the nature and location of these materials
should be documented and their condition should be reassessed periodically.
The questions in Figure 1 5 are based on the assessment factors discussed in Section 3.2.2.2.
The evaluation of factors that indicate material condition and the potential for erosion or
disturbance is subjective. For example, determining if water damage is evident or the material
is accessible requires judgment by trained and/or experienced evaluators. The descriptions of
individual assessment factors in Appendix D are an excellent starting point for training
evaluators.
Once Figure 15 has been used to choose between a special operations and maintenance
program or the direct treatment of asbestos-containing materials, the decision-maker is
directed to Table 2, which summarizes asbestos control alternatives. Advantages and
disadvantages of each control measure are presented together with information on approp-
riate and inappropriate applications.
Several items in Table 2 are particularly important:
• Removal has the widest applicability of all control alternatives. It also is the only
truly permanent solution, since no building containing asbestos can be demolished
without first removing the asbestos. It is the only control measure which can
guarantee elimination of asbestos exposure.
• Enclosure and encapsulation must be followed with a special operations program
and with periodic reinspection of the enclosed or encapsulated materials.
• Removal, enclosure, and encapsulation should be undertaken only after construc-
tion of sealed containment barriers.
• Proper worker protection is mandated by OSHA for removal operations, and is
needed for enclosure and encapsulation activities as well.
Table 2 shows that the initial cost of removal may be higher than for the other control
measures. However, several building owners have found that long-term costs of removal may
be lower when considering the need for special operations practices, periodic reinspection,
and repairs if the material is enclosed or encapsulated. The cost of eventually removing
enclosed or encapsulated materials prior to demolition must also be considered.
3-26
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-------
CHAPTER 4 - DETERMINING ABATEMENT COMPLETION
Determining successful performance on individual abatement projects is one of the most
difficult problems faced by the asbestos program manager. Insistence on specific work
practices and continuing surveillance during abatement are essential to a successful
abatement project. Releasing the contractor from a project depends on specific criteria being
met. This chapter discusses two types of criteria—visual inspection of the worksite and air
monitoring after completion of the project. Major points in this chapter are summarized
below.
Visual Inspection: Regardless of other abatement performance measures con-
sidered, a visual inspection should always be made. The nature of visual inspection
will vary with the type of abatement activity. The inspection should detect incomplete
work, damage caused by the abatement activity, and inadequate cleanup of the
worksite.
Air Monitoring: Measurement of total airborne fibers by phase contrast microscopy
should supplement visual inspection to confirm adequate job cleanup. Such
measurement can determine whether elevated levels of airborne fibers generated
during the abatement project have been sufficiently reduced.
4.1 Visual Inspection
Every abatement contract should require a thorough visual inspection of the worksite after
project completion. The inspection should be conducted before the containment barriers have
been taken down but after the plastic sheets have been cleaned with damp mops and cloths.
Only after the worksite has passed inspection should the contractor be released. The
inspector (program manager or technical expert) first should check on the completeness of the
job. If asbestos-containing material has been removed, all substrate surfaces should be
inspected for adhering material. Special attention should be given to pipes, beams, and
irregular surfaces that may have corners and areas that are difficult to reach. Enclosures
should be checked for tight construction (for example, no stray drill holes or openings at
enclosure corners). Encapsulated surfaces should be inspected for thin application of sealant.
Surfaces behind obstructions (for example, pipes or ducts) are suspect areas and should be
checked.
Visual inspection also should include a check for damage. Wet removal with inadequate floor
protection may cause warping of wooden floors. Also, disassembling the containment
barriers sometimes causes wall or ceiling paint to peel.
A third function of the visual inspection is to ensure that the worksite has been adequately
cleaned. Any activity which disturbs asbestos-containing material will release fibers. There-
fote, worksite cleanup after removal, enclosure, or encapsulation activities is critical. All
surfaces should be checked for dust and debris, especially overhead surfaces such as tops of
suspended light fixtures. Use a damp cloth to collect dust from these surfaces and then
inspect the cloth for visible evidence of dust. This is a convenient way to establish that the "no
dust requirement has been met.
4.2 Air Monitoring
Visual inspection can be used to check for fiber accumulation (as well as general debris) on
floors and other surfaces. It cannot measure the level of residual asbestos fibers in the air. Air
monitoring thus can be used along with visual inspection to be sure the worksite is clean.
Monitoring should be conducted only after the worksite has passed a thorough visual
inspection.
4-1
-------
As discussed in Chapter 3 (Section 3.3.2), the direct measurement of airborne asbestos fibers
requires the use of electron microscopy (EM) and is both technically complex and expensive.
However, the NIOSH recommended air monitoring method based on phase contrast micro-
scopy (PCM) is a practical alternative to EM for this application. The detection limit of PCM can
be used to establish that levels of total (asbestos and nonasbestos) fibers generated during an
abatement action have been sufficiently reduced. Using the sampling specifications described
below coupled with PCM measurement provides a practical air monitoring test to complement
visual inspection as criteria for releasing abatement contractors.
The following sampling and analysis specifications are suggested for air monitoring after
project completion and before containment barriers are dismantled:
• Sampling should begin after all surfaces at the worksite have dried but preferably
within 48 hours after abatement work is finished.
• A total of approximately 1,000 liters or more of air should be sampled at a rate of
no more than 2 liters per minute. (Thus, an 8-hour sampling period would produce
a sample volume of 960 liters.)
• A minimum of three monitors per worksite and at least one per room should be
used.
For a sample volume of approximately 1,000 liters of air, the lower detection limit for phase
contrast microscopy is about 0.03 fibers per cubic centimeter.* It must be noted that the lower
detection limit decreases as the volume of air sampled increases. Therefore, if the lower
detection limit is used as a standard for releasing the contractor, the standard can be made
more stringent (lower than 0.03 fibers per cubic centimeter) by increasing the volume of air
sampled.
Table 3 shows calculated detection limits for various sampling volumes. As shown, a
sampling volume of almost 3,000 liters will decrease the detection limit of PCM to 0.01 fibers
per cubic centimeter. This table also can serve as a guide for determining whether levels of
airborne fibers reported by air monitoring contractors are reliable for sampling volumes less
than 1,000 liters, even though such low volumes are not recommended. More information on
detection limits can be found in Appendix G.
Table 3. Total Airborne Fiber Detection Limits and Associated
Sampling Volumes (for the NIOSH P&CAM 239 Method)
Sampling time @ Volume collected
2 liters per minute (liters)
(hours)
2
6
8
24
Not ( 240
recommended j 720
960
2,880
Detection limit3
(fibers per cubic
centimeter)
0
0
0
0
119
041
030
010
aAssumes a microscopic field area of 0 003 square millimeters Some
microscopes have field areas as large as 0.006 square millimeters,
which would decrease the detection limits shown by half See
Appendix G for details.
*This determination is based on a minimum detection limit of 10 fibers per 100 microscopic fields for
PCM reported in Leidel, et al 1 979. See Appendix G for additional information on calculating detection
limits.
4-2
-------
Regardless of what air level is selected as the standard for releasing abatement contractors, it
should be applied at each monitor. If any monitor shows a total fiber level higher than that
allowed, the worksite should be recleaned with a HEPA-filtered vacuum cleaner and/or damp
cloths and mops. A new set of air samples for the entire worksite should be collected and
analyzed.
It is important to acknowledge that PCM measurements of airborne fibers at the worksite
following project completion serve only to indicate that the elevated levels of total fibers
observed during the abatement action have been reduced. The PCM measurements cannot be
used to document the absolute levels of asbestos in the building.
4-3
-------
References
Constant PC Jr, Bergman FJ, Atkinson GR, Rose DR, Watts DL, Logue EE, Hartwell TD,
Price BP, Ogden JS. 1982. Airborne Asbestos Levels in Schools. Draft report. Washington,
DC: Office of Pesticides and Toxic Substances. U.S. Environmental Protection Agency,
Contracts 68-01-5915 and 68-01-5848.
Lory EE. 1980. Asbestos Friable Insulation Material (FIM) Risk Evaluation Procedure for Navy
Facilities. Port Hueneme, CA: Civil Engineering Laboratory, U.S. Navy.
Lucas D, Hartwell T, Rao AV. 1980a. Asbestos-Containing Materials in School Buildings:
Guidance for Asbestos Analytical Programs. Washington, DC: Office of Toxic Substances,
U.S. Environmental Protection Agency.
Lucas D, Hartwell T, Rao AV. 1980b. Asbestos-Containing Materials in School Buildings:
Guidance for Asbestos Analytical Programs, Statistical Background Document. Washington,
DC: Office of Toxic Substances, U.S. Environmental Protection Agency.
Nicholson WJ, Rohl AM, Ferrand EF. 1971. "Asbestos Air Pollution in New York City." In:
Proceedings of Clean Air Congress. England HM, Barry WT, eds. New York: Academic.
Nicholson WJ, Rohl AM, Weisman I. 1975. Asbestos Contamination of the Air in Public
Buildings. Washington, DC: U.S. Environmental Protection Agency.
Pinchin DJ. 1982 (June). Asbestos in Buildings. Mississauga, Ontario, Canada: Ontario
Research Foundation.
Samudra AV, Horwood CF, Stockham JD. 1977 (revised June 1978). Electron Microscope
Measurement of Airborne Asbestos Concentrations. Research Triangle Park, NC: Office of
Research and Development, U.S. Environmental Protection Agency.
*
Sawyer RN, Spooner DM. 1979b. Asbestos-Containing Materials in School Buildings: A
Guidance Document, Part 2. Washington, DC. Office of Toxic Substances, U.S. Environmental
Protection Agency.
Sebastien P, Bellon-Galland MA, Dufour G, Petit G, Goudichet A. 1982. Assessment of
Asbestos Exposure in Buildings with Sprayed Materials Using Both the Algorithm Method and
the ATEMMeasurement Method. Paris, France: Direction des Affaires Sanitaires et Sociales
de Paris.
USEPA. 1979. U.S. Environmental Protection Agency. Asbestos-Containing Materials in
School Buildings: A Guidance Document, Part 1. Washington, DC: Off ice of Toxic Substances,
USEPA.
USEPA. 1980. U.S. Environmental Protection Agency. Asbestos-Containing Materials in
Schools, Economic Impact Analysis of Identification and Notification Proposed Rule, Sec. 6,
TSCA. Washington, DC: Office of Toxic Substances, USEPA. EPA-560/1 2-80-004.
USEPA. 1981. U.S. Environmental Protection Agency. Evaluation of Encapsulants for
Sprayed-On Asbestos-Containing Materials in Buildings. Summary. Cincinnati, OH: Office of
Research and Development, USEPA.
R-1
-------
USEPA. 1982. U.S. Environmental Protection Agency. Support Document for Final Rule on
Friable Asbestos-Containing Materials in School Buildings: Health Effects and Magnitude of
Exposure. Washington, DC: Office of Toxic Substances, USEPA.
Versar Inc. 1 980. Exposures to Commercial Asbestos. Sec. 3: Comparability of Asbestos Data.
Preliminary draft report. Washington, DC: Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency. Contract No. 68-01-5791.
R-2
-------
Appendix A. Common Units Used in Measuring
Airborne Asbestos Concentrations
Length
1 meter (m) = 39.37 inches or 3.28 feet
100 centimeters (cm) = 1 meter
1,000,000 micrometers (/urn) = 1 meter
Volume
1 cubic m (m3) = 35.3 cubic feet
1,000,000 cm3 = 1 m3
1,000cm3 = 1 liter
Weight (mass)
454 grams (g) = 1 pound
1,000,000,000 nanograms (ng)
1 gram
Concentration (mass contained in a stated volume)
2 fibers per cm3 (the current 8-hour OSHA industrial standard) means that 2 fibers are
present in each cm3 of air. Since there are 1,000,000 cm3 in 1 m3, there would be 2,000,000
fibers in a m3.
If each fiber is chrysolite asbestos (density of 0.0026 ng//ym3) and is just long and thick
enough to be detected by the NIOSH procedure for determining compliance with the OSHA
standard (5 //m in length and 0.3 //m in diameter), it would weight 0.0092 ng:
Mass = 7T/4 (diameter)2 (length) (density)
7T/4 (0.3 //m)2 (5 /urn) (0.0026 ng///m3) = 0.0092 ng
A total-of 2,000,000 of these fibers would weigh about 1,800 ng.
Since the fibers in the above example are the smallest (shortest and thinnest) counted by the
NIOSH procedure, fibers actually measured using this protocol are typically larger and thus
weigh more. Comparison of fibers in this example with those actually measured is further
complicated since nonasbestos as well as asbestos fibers are counted by the NIOSH protocol.
As noted in the footnote to Figure 1, comparisons of total fibers counted with the mass of
A-1
-------
asbestos measured in air samples indicate that, on an average, about 30 fibers counted by the
NIOSH procedures equal one nanogram of asbestos. This relationship applies to samples
collected during the spray application of asbestos insulation. For these samples, each fiber
counted weighs an average of 0.033 ng, or about 37 times more than those in the example,
and 2,000,000 of them would weigh about 67,000 ng.
A-2
-------
Appendix B. Addresses of EPA Regional Asbestos Coordinators
EPA Region I
Asbestos Coordinator
Air and Hazardous Material Division
JFK Federal Building
Boston, Massachusetts 02202
(617)223-0585
EPA Region II
Asbestos Coordinator
Woodbridge Avenue
Edison, New Jersey 08837
(201)321-6668
EPA Region III
Asbestos Coordinator
Curtis Building
6th and Walnut Street
Philadelphia, Pennsylvania 19106
(215)597-9859
EPA Region IV
Asbestos Coordinator
345 Cortland Street
Atlanta, Georgia 30365
(404)881-3864
EPA Region V
Asbestos Coordinator
230 S. Dearborne Street
Chicago, Illinois 60604
(312)886-6003
EPA Region VI
Asbestos Coordinator
First International Building
1219 Elm Street
Dallas, Texas 75270
(214)767-2734
EPA Region VII
Asbestos Coordinator
324 E. 11th Street
Room 1411
Kansas City, Missouri 64106
(816)374-6538
EPA Region VIII
Asbestos Coordinator
1860 Lincoln Street
Denver, Colorado 80295
(303) 837-3926
EPA Region IX
Asbestos Coordinator
215 Fremont Street
San Francisco, California 94105
(415)974-8123
EPA Region X
Asbestos Coordinator
1200 6th Avenue
Seattle, Washington 98101
(206) 442-2632
B-1
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Appendix C. Asbestos-Containing Materials Found in Buildings*
Asbestos-containing construction materials and products
can be divided into two categories:
• Category I — Friable materials; and
• Category II — Nonfriable matrix-bonded composite products, and textile products.
Friable materials are those which can be crumbled, pulverized, or reduced to powder in the
hand—readily releasing fibers with minimal mechanical disturbance. Most insulating mate-
rials sprayed or troweled onto surfaces are friable.
Nonfriable, matrix-bonded composite products are prepared by mixing fibers with various
bonding agents (e.g., starch, glue, plastics, cements, asphalt). The degree of asbestos fiber
immobilization and the degree of release vary according to use, environmental conditions,
and physical damage. Friable materials covered with a hard wrap or coating, such as pipe
insulation, are considered nonfriable unless damage to the wrap exposes the friable material.
In asbestos textile products, raw asbestos fibers and fibers of numerous other materials, both
of organic and inorganic origin, are worked into rovings, yarns and cords and can be woven,
braided, or knitted. Usually, binding agents are not used in these products but many are
coated.
Each of the two major categories can be subdivided into several more specific groups of
products. Table C-1 contains information on the percent asbestos, generic name, dates of use,
and binder/sizing of the subdivision.
'The information in this Appendix is taken, with modification, from: Lory EE, Coin DC. February 1981.
Management Procedure for Assessment of Friable Asbestos Insulating Material. Port Hueneme, CA:
Civil Engineering Laboratory Naval Construction Battalion Center. The U.S. Navy prohibits the use of
asbestos-containing materials when acceptable nonasbestos substitutes have been identified.
C-1
-------
Table C-1. Various Types of Friable and Nonfriable Materials and Products (as of 1977)
Subdivision
Friable insulation material
Preformed thermal
insulating products
Textiles
Cementitious
concrete-like products
Paper products
Roofing felts
Generic name
spray-applied insulating
batts, blocks, and
pipe covering
85% magnesia
calcium silicate
cloth8
blankets (fire)a
felts
blue stripe
red stripe
green stripe
sheets
cord/rope/yarn9
tubing
tape/strip
curtains3
(theatre, welding)
extrusion panels
corrugated
flat
flexible
flexible perforated
laminated
(outer surface)
roof tiles
clapboard and shingles
clapboard
siding shingles
roofing shingles
pipe
corrugated
high temperature
moderate temperature
indented
millboard
smooth surface
mineral surface
shingles
pipeline
Asbestos (%)
1-95
15
6-8
100
90-95
80
90
95
50-95
80- 1 00
80-85
90
60-65
8
20-45
40-50
30-50
30-50
35-50
20-30
12-15
12-14
20-32
20-15
90
35-70
98
80-85
10-15
10-15
1
10
Dates of use
1935-1970
1926-1949
1949-1971
1910-present
1920-present
1920-present
1920-present
1920-present
1920-present
1920-present
1920-present
1920-present
1 945-present
1965-1977
1930-present
1930-present
1930-present
1930-present
1930-present
1930-present
1944-1945
unknown- present
unknown-present
1 935-present
1935-present
1910-present
1935-present
1 925-present
1910-present
1910-present
1971-1974
1920-present
Binder/sizing
sodium silicate,
Portland cement,
organic binders
magnesium carbonate
calcium silicate
none
cotton/wool
cotton
cotton
cotton
cotton/wool
cotton/wool
cotton/wool
cotton /wool
cotton
Portland cement
Portland cement
Portland cement
Portland cement
Portland cement
Portland cement
Portland cement
Portland cement
Portland cement
protland cement
Portland cement
sodium silicate
starch
cotton and organic binder
starch, lime, clay
asphalt
asphalt
asphalt
asphalt
C-2
-------
Table C-1. (continued)
Subdivision
Asbestos-containing
compounds
Asbestos ebony products
Flooring tile and
Sheet Goods
Wallcovering
Paints and coatings
Generic name
caulking putties
adhesive (cold applied)
joint compound
roofing asphalt
mastics
asphalt tile cement
roof putty
plaster/stucco
spackles
sealants fire/water
cement, insulation
cement, finishing
cement, magnesia
vinyl/asbestos tile
asphalt/asbestos tile
sheet goods/resilient
vinyl wallpaper
roof coating
air tight
Asbestos (%)
30
5-25
5
5-25
13-25
10-r25
2-10
3-5
50-55
20-100
55
15
50
21
26-33
30
6-8
4-7
15
Dates of use
1 930-present
1945-present
1945-1975
unknown-present
1920-present
1959-present
unknown-present
unknown-present
1930-1975
1935-present
1900-1973
1920-1973
1926-1950
1 930-present
1950-present
1920-present
1950-present
unknown-present
1 900-present
1 940-present
Binder/sizing
linseed oil
asphalt
asphalt
asphalt
asphalt
asphalt
asphalt
Portland cement
starch, casein, synthetic
resins
caster oil or polyisobutylene
clay
clay
magnesium carbonate
Portland cement
poly(vmyl)cnloride
asphalt
dry oils
—
asphalt
asphalt
laboratory aprons, gloves, cord, rope, fire blankets, and curtains may be common in schools.
C-3
-------
Appendix D. Definition and Description of Factors for
Assessing the Need for Corrective Action*
D.1 Condition of the Asbestos-Containing Material
D.I .1 Factors 1 and 2: Deterioration or Delamination and Physical Damage
An assessment of the condition should evaluate: the quality of the installation, the adhesion
of the friable material to the underlying substrate, deterioration, and damage from vandalism
or any other cause. Evidence of debris on horizontal surfaces, hanging material, dislodged
chunks, scrapings, indentations, or cracking are indicators of poor material condition.
Accidental or deliberate physical contact with the friable material can result in damage.
Inspectors should look for any evidence that the asbestos-containing material has been
disturbed: finger marks in the material, graffiti, pieces dislodged or missing, scrape marks
from movable equipment or furniture, or accumulation of the friable material on floors,
shelves, or other horizontal surfaces.
Asbestos-containing material may deteriorate as a result of either the quality of the
installation or environmental factors which affect the cohesive strength of the asbestos-
containing material or the strength of the adhesion to the substrate. Deterioration can result
in the accumulation of dust on the surface of the asbestos-containing material, delamination
of the material (i.e., separating into layers), or an adhesive failure of the material where it
pulls away from the substrate and either hangs loosely or falls to the floor and exposes the
substrate. Inspectors should touch the asbestos-containing material and determine if dust is
released when the material is lightly brushed or rubbed.
If the coated surface "gives" when slight hand pressure is applied or the material moves up
and down with light pushing, the asbestos-containing material is no longer tightly bonded to
its substrate.
D.I .2 Factor 3: Water Damage
Water damage is usually caused by roof leaks, particularly in buildings with flat roofs or a
concrete slab and steel beam construction. Skylights can also be significant sources of leaks.
Water damage can also result from plumbing leaks and water or high humidity in the vicinity
of pools, locker rooms, and lavatories.
Water can dislodge, delaminate, or disturb friable asbestos-containing materials that are
otherwise in good condition and can increase the potential for fiber release by dissolving and
washing out the binders in the material. Materials which were not considered friable may
become friable after water has dissolved and leached out the binders. Water can also act as a
slurry to carry fibers to other areas where evaporation will leave a collection of fibers that can
become suspended in the air.
Inspect the area for visible signs of water damage, such as discoloration of or stains on the
asbestos-containing material; stains on adjacent walls or floors; buckling of the walls or
*The information in this Appendix is taken, with modification, from: Brandner, W. October 1982.
Asbestos Exposure Assessment in Buildings Inspection Manual. Kansas City, MO: U.S. Environ-
mental Protection Agency, Region VII.
D-1
-------
floors; or areas where pieces of the asbestos-containing material have separated into layers
or fallen down, thereby exposing the substrate.
Close inspection is required. In many areas, staining may occur only in a limited area while
water damage causing delamination may have occurred in a much larger area. In addition, the
water damage may have occurred since the original inspection for friable material, causing
new areas to become friable and require a reinspection.
Delamination is particularly a problem in areas where the substrate is a very smooth concrete
slab. Check to see if the material "gives" when pressure is applied from underneath.
D.2 Potential for Disturbance or Erosion
D.2.1 Factor 4: Air Plenum or Direct Airstream
An air plenum exists when the return (or, in rare cases, conditioned) air leaves a room or hall
through vents in a suspended ceiling and travels at low speed and pressure through the space
between the actual ceiling and the suspended ceiling or ducts. The moving air may erode any
asbestos-containing material in the plenum. In evaluating whether an air plenum or direct
airstream is present, the inspector must look for evidence of ducts or cavities used to convey
air to and from heating or cooling equipment or the presence of air vents or outlets which
blow air directly onto friable material.
A typical construction technique is to use the space between a suspended ceiling and the
actual ceiling as a return air plenum. In many cases, the tiles in the suspended ceiling must be
lifted to check if this is the case. Inspection of the air handling or HVAC equipment rooms may
also provide evidence (such as accumulated fibers) of the presence of this material in the
plenums.
Special attention should be paid to whether frequent activities (such as maintenance) disturb
the material in the plenum. It is also important to check for evidence that the material is being
released or eroded (i.e., has it deteriorated or been damaged so that the material is free to
circulate in the airstream?).
D.2.2 Factor 5: Exposure, Accessibility, and Activity
These three considerations are highly interrelated and have been combined into a single
factor. In general, for a site to show a high potential for disturbance, it must be exposed
(visible) and accessible, and be located near movement corridors or subject to vibration.
The amount of asbestos-containing material exposed to the area occupied by people will
contribute to the likelihood that the material may be disturbed and determines whether the
fibers can freely move through the area. An asbestos-containing material is considered
exposed if it can be seen. For a material not to be exposed, a physical barrier must be
complete, undamaged, and unlikely to be removed or dislodged. An asbestos-containing
material should be considered exposed if it is visible, regardless of the height of the material.
If the asbestos-containing material is located behind a suspended ceiling with movable tiles, a
close inspection must be made of the condition of the suspended ceiling; the likelihood and
frequency of access into the suspended ceiling, and whether the suspended ceiling forms a
complete barrier or is only partially concealing the material.
D-2
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Asbestos-containing material above a suspended ceiling is considered exposed if the space
above the suspended ceiling is an air plenum. Suspended ceilings with numerous louvers,
grids, or other open spaces should be considered exposed.
If friable asbestos-containing material can be reached by building users or maintenance
people, either directly or by impact from objects used in the area, it is accessible and subject to
accidental or intentional contact and damage. Material which is accessible is likely to be
disturbed in the future.
Height above the floor is one measure of accessibility. However, objects have been observed
embedded in ceilings 25 feet or more high. Nearness of the friable asbestos-containing
material to heating, ventilation, lighting and plumbing systems requiring maintenance or
repair may increase the material's accessibility.
In addition, the activities and behavior of persons using the building should be included in the
assessment of whether the material is accessible. For example, persons involved in athletic
activities may accidentally damage the material on the walls and ceilings of gymnasiums with
balls or athletic equipment. To become fully aware of occupants' use of the building, the
inspector should consult with building staff or personnel.
When assessing activity levels, consider not only the movement caused by the activities of
people but also movement from other sources such as high vibration from mechanical
equipment, highways, and airplanes. Another source of vibration is sound, such as music and
noise, which sets airwaves in motion at certain frequencies. As these sound waves impact on
asbestos-containing material, they may vibrate the material and contribute to fiber release.
Therefore, more fibers may be released in a music practice room or auditorium than in the
rest of the building.
The amount of activity of the occupants can best be described by identifying the purpose of the
area as well as estimating the number of persons who enter the area on a typical day.
D.2.3 Factor 6: Change in Building Use
A planned change in the use of the building from, for example, a junior to a senior high school
may imply significant changes in the potential for erosion or disturbance. Of particular note is
the increased potential for damage from balls to previously inaccessible ceilings in gymna-
siums. The addition of machinery (such as dust collectors in wood or metal shops) to a school
or office building may introduce vibrations which, again, may be a future cause of concern.
The inspector should exercise judgement and draw on experience in evaluating the likely
effect of such changes.
D-3
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Appendix E. Example Building Inspection Form
BUILDINGS EVALUATION FORM #2
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VII - TOXICS AND PESTICIDES SECTION Date:
324 EAST 11TH STREET
KANSAS CITY, MISSOURI 64106 Dist. No.:
Room: Sample Number(s):
Building: Address:
Evaluator: Phone No.:
Coated Area: Ceiling Wall(s) Structural Members Above Suspended Ceiling
Pipe Lagging Boiler Insul. Other:
Type of
Ceiling: Concrete 3 Coat Plaster System Suspended Metal Lath
Concrete Joists and Beams Tile Suspended Lay-In Panels
Metal Deck Corrugated Steel Steel Beam or Bar Joists
Ceiling Height: ft.
r\
Ceiling Shape: Flat Dome Other
(draw):
Folded Plate Barrel
Type of Wall (If Coated): Smooth Concrete Rough Concrete Masonry
Plasterboard Other:
Amount of Friable Material in Area being Evaluated: sq. ft.
Description Fibrous Granular/Cementitious Concrete Like
of Coating: (highly friable) (soft) (hard)
Thickness: inch(s) Is thickness uniform: Yes No
Coating debris on Floor/Furniture/Work Surfaces: Yes No
Curtains, expandable partitions, etc. being pulled across coating: Yes No
Type of Lighting: Surface Mounted Suspended Recessed
No. of Lights: Type of Heating/Cooling Systems: __
Type of Floor: Concrete Tile Wood Carpet Other:
What is above the room being evaluated?
Comments:
E-1
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E.1 Notes to Appendix E
The need for collecting most of the information on this form is discussed in Chapter 3 (Section
3.3.1). The form requires one additional piece of information: the presence of curtains or
expandable partitions which are pulled across asbestos-containing material. Where this
situation is found, the curtains or partitions should be removed or repositioned to eliminate
contact with the material. Any damage to the asbestos-containing material then can be
repaired.
This form was provided by Wolfgang Brandner, the Regional Asbestos Coordinator in Region
VII.
E-2
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Appendix F. Recommended Specifications and Operating
Procedures for the Use of Negative Pressure
Systems for Asbestos Abatement*
F.1. Introduction
This appendix provides guidelines for the use of negative pressure systems in removing
asbestos-containing materials from buildings. A negative pressure system is one in
which static pressure in an enclosed work area is lower than that of the environment outside
the containment barriers.
The pressure gradient is maintained by moving air from the work area to the environment
outside the area via powered exhaust equipment at a rate that will support the desired air flow
and pressure differential. Thus, the air moves into the work area through designated access
spaces and any other barrier openings. Exhaust air is filtered by a high-efficiency particulate
air (HEPA) filter to remove asbestos fibers.
The use of negative pressure during asbestos removal protects against large-scale release of
fibers to the surrounding area in case of a breach in the containment barrier. A negative
pressure system also can reduce the concentration of airborne asbestos in the work area by
increasing the dilution ventilation rate (i.e., diluting contaminated air in the work area with
uncontaminated air from outside) and exhausting contaminated air through HEPA filters. The
circulation of fresh air through the work area reportedly also improves worker comfort, which
may aid the removal process by increasing job productivity.
F.2 Materials and Equipment
F.2.1 The Portable, HEPA-Filtered, Powered Exhaust Unit
The exhaust unit establishes lower pressure inside than outside the enclosed work area
during asbestos abatement. Basically, a unit (see Figure F-1) consists of a cabinet with an
opening at each end, one for air intake and one for exhaust. A fan and a series of filters are
arranged inside the cabinet between the openings. The fan draws contaminated air through
the intake and filters and discharges clean air through the exhaust.
Portable exhaust units used for negative pressure systems in asbestos abatement projects
should meet the following specifications.
F.2.1.1 Structural Specifications
The cabinet should be ruggedly constructed and made of durable materials to withstand
damage from rough handling and transportation. The width of the cabinet should be less than
30 inches to fit through standard-size doorways. The cabinet must be appropriately sealed to
prevent asbestos-containing dust from being emitted during use, transport, or maintenance.
There should be easy access to all air filters from the intake end, and the filters must be easy
* Information in this Appendix is taken, with modification, from PEDCo Environmental, Inc., April 1982.
Continued Evaluation of Asbestos Removal Technologies and Recommended Specifications of
Negative Pressure Systems. Washington, DC: Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency. Contract No. 68-02-3173.
F-1
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Inlet
__
—
_
_— ^
0 OOOOOOOOOOOOO
Prefilter
Intermediate
filter
Exhaust
HEPA filter
Rubber
gasket
Figure F-1 Sketch of HEPA-filtered exhaust unit
to replace. The unit should be mounted on casters or wheels so it can be easily moved. It also
should be accessible for easy cleaning.
F.2.1.2 Mechanical Specifications
F. 2.1.2.1 Fans
The fan for each unit should be sized to draw a desired air flow through the filters in the unit
at a specified static pressure drop. The unit should have an air-handling capacity of 1,000 to
2,000 ftVmin (under "clean" filter conditions). The fan should be of the centrifugal type.
For large-scale abatement projects, where the use of a larger capacity, specially designed
exhaust system may be more practical than several smaller units, the fan should be
appropriately sized according to the proper load capacity established for the application, i.e..
Total ftVmin (load) =
Volume of air in ft3 x air changes/hour
60 min/hour
F-2
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Smaller-capacity units (e.g., 1,000 ftVmin) equipped with appropriately sized fans and filters
may be used to ventilate smaller work areas. The desired air flow could be achieved with
several units.
F.2.1.2.2 Filters
The final filter must be the HEPA type. Each filter should have a standard nominal rating of at
least 1,100ft3/min with a maximum pressure drop of 1 inch H2O clean resistance. The filter
media (folded into closely pleated panels) must be completely sealed on all edges with a
structurally rigid frame and cross-braced as required. The exact dimensions of the filter
should correspond with the dimensions of the filter housing inside the cabinet or the
dimensions of the filter-holding frame. The recommended standard size HEPA filter is 24
inches high x 24 inches wide x 11-1/2 inches deep. The overall dimensions and squareness
should be within 1 /8 inch.
A continuous rubber gasket must be located between the filter and the filter housing to form a
tight seal. The gasket material should be 1 /4 inch thick and 3/4 inch wide.
Each filter should be individually tested and certified by the manufacturer to have an
efficiency of not less than 99.97 percent when challenged with 0.3-fjm dioctylphthalate (OOP)
particles. Testing should be in accordance with Military Standard Number 282 and Army
Instruction Manual 136-300-175A. Each filter should bear a UL586 label to indicate ability to
perform under specified conditions.
Each filter should be marked with: the name of the manufacturer, serial number, air flow
rating, efficiency and resistance, and the direction of test air flow.
Prefilters, which protect the final filter by removing the larger particles, are recommended to
prolong the operating life of the HEPA filter. Prefilters prevent the premature loading of the
HEPA filter. They can also save energy and cost. One (minimum) or two (preferred) stages of
prefiltration may be used. The first-stage prefilter should be a low-efficiency type (e.g., for
particles 10 //m and larger). The second-stage (or intermediate) filter should have a medium
efficiency (e.g., effective for particles down to 5 /um). Various types of filters and filter media
for prefiltration applications are avaj]aj)le_fmm_many manufacturers. Prefilters and inter-
mediate filters should be installed either on or in the intake grid of the unit and held in place
with special housings or clamps.
F.2.1.2.3 Instrumentation
Each unit should be equipped with a Magnehelic gauge or manometer to measure the
pressure drop across the filters and indicate when filters have become loaded and need to be
changed. The static pressure across the filters (resistance) increases as they become loaded
with dust, affecting the ability of the unit to move air at its rated capacity.
F.2.1.3 Electrical
F.2.1.3.1 General
The electrical system should have a remote fuse disconnect. The fan motor should be totally
enclosed, fan-cooled, and the nonoverloading type. The unit must use a standard 115-V,
F-3
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single-phase, 60-cycle service. All electrical components must be approved by the National
Electrical Manufacturers Association (NEMA) and Underwriter's Laboratories (UL).
F.2.1.3.2 Fans
The motor, fan, fan housing, and cabinet should be grounded. The unit should have an
electrical (or mechanical) lockout to prevent'the fan from operating without a HEPA filter.
F.2.1.3.3 Instrumentation
An automatic shutdown system that would stop the fan in the event of a major rupture in the
HEPA filter or blocked air discharge is recommended. Optional warning lights are recom-
mended to indicate normal operation, too high of a pressure drop across the filters (i.e., filter
overloading), and too low of a pressure drop (i.e., major rupture in HEPA filter or obstructed
discharge). Other optional instruments include a timer and automatic shut-off and an elapsed
time meter to show the total accumulated hours of operation.
F.3 Setup and Use of a Negative Pressure System
F.3.1 Preparation of the Work Area
F.3.1.1 Determining the Ventilation Requirements for a Work Area
Experience with negative pressure systems on asbestos abatement projects indicates a
recommended rate of one air change every 15 minutes. The volume (in ft3) of the work area is
determined by multiplying the floor area by the ceiling height. The total air flow requirement
(in ftVmin) for the work area is determined by dividing this volume by the recommended air
change rate (i.e., one air change every 15 minutes).*
Total ftVmin = Volume of work area (in ft3)/15 min
The number of units needed for the application is determined by dividing the total ftVmin by
the rated capacity of the exhaust unit.
Number of units needed = [Total ft3/min]/[Capacity of unit (in ft3)]
F.3.1.2 Location of Exhaust Units
The exhaust unit(s) should be located so that makeup air enters the work area primarily
through the decontamination facility and traverses the work area as much as possible. This
may be accomplished by positioning the exhaust unit(s) at a maximum distance from the
worker access opening or other makeup air sources.
Wherever practical, work area exhaust units can be located on the floor in or near unused
doorways or windows. The end of the unit or its exhaust duct should be placed through an
opening in the plastic barrier or wall covering. The plastic around the unit or duct should then
be sealed with tape.
'The recommended air exchange rate is based on engineering judgment.
F-4
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Each unit must have temporary electrical power (115V AC). If necessary, three-wire extension
cords can supply power to a unit. The cords must be in continuous lengths (without splice), in
good condition, and should not be more than 100 feet long. They must not be fastened with
staples, hung from nails, or suspended by wire. Extension cords should be suspended off the
floor and out of workers' way to protect the cords from damage from traffic, sharp objects, and
pinching.
Wherever possible, exhaust units should be vented to the outside of the building. This may
involve the use of additional lengths of flexible or rigid duct connected to the air outlet and
routed to the nearest outside opening. Windowpanes may have to be removed temporarily.
If exhaust air cannot be vented to the outside of the building or if cold temperatures
necessitate measures to conserve heat and minimize cold air infiltration, filtered air that has
been exhausted through the barrier may be recirculated into an adjacent area. However, this
is not recommended.
Additional makeup air may be necessary to avoid creating too high of a pressure differential,
which could cause the plastic coverings and temporary barriers to "blow in." Additional
makeup air also may be needed to move air most effectively through the work area.
Supplemental makeup air inlets may be made by making openings in the plastic sheeting that
allow air from outside the building into the work area. Auxiliary makeup air inlets should be as
far as possible from the exhaust unit(s) (e.g., on an opposite wall), off the floor (preferably near
the ceiling), and away from barriers that separate the work area from occupied clean areas.
They should be resealed whenever the negative pressure system is turned off after removal
has started. Because the pressure differential (and ultimately the effectiveness of the system)
is affected by the adequacy of makeup air, the number of auxiliary air inlets should be kept to a
minimum to maintain negative pressure. Figure F-2 presents examples of negative pressure
systems denoting the location of HEPA-filtered exhaust units and the direction of airflow.
F.3.2 Use of the Negative Pressure System
F.3.2.1 Testing the System
The negative pressure system should be tested before any asbestos-containing material is
wetted or removed. After the work area has been prepared, the decontamination facility set
up, and the exhaust unit(s) installed, the unit(s) should be started (one at a time). Observe the
barriers and plastic sheeting. The plastic curtains of the decontamination facility should move
slightly in toward the work area. The use of ventilation smoke tubes and a rubber bulb is
another easy and inexpensive way to visually check system performance and direction of air
flow through openings in the barrier. Another test is to use a Magnehelic gauge (or other
instrument) to measure the static pressure differential across the barrier. The measuring
device must be sensitive enough to detect a relatively low pressure drop. A Magnehelic gauge
with a scale of 0 to 0.25 or 0.50 inch of H2O and 0.005 or 0.01 inch graduations is generally
adequate. The pressure drop across the barrier is measured from the outside by punching a
small hole in the plastic barrier and inserting one end of a piece of rubber or Tygon tubing. The
other end of the tubing is connected to the "low pressure" tap of the instrument. The "high
pressure" tap must be open to the atmosphere. The pressure is read directly from the scale.
After the test is completed, the hole in the barrier must be patched.
F-5
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DF
Exhaust duct
vented
window
i WA C WA Auxiliary
T 1 makeup air
i — 1— i 1 i 1 1 i 1 1 i 1 — |— i
r LJEU i
\ *
;EU| i
DF
Figure F-2. Examples of negative pressure systems. DF, Decontamination Facility; EU, Exhaust Unit; WA, Worker
Access; A, Single-room work area with multiple windows; B, Single-room work area with single window near
entrance; C, Large single-room work area with windows and auxiliary makeup air source (dotted arrow). Arrows
denote direction of air flow. Circled numbers indicate progression of removal sequence.
F-6
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F.3.2.2 Use of System During Removal Operations
The exhaust units should be started just before beginning removal (i.e., before any asbestos-
containing material is disturbed). After removal has begun, the units should run continuously
to maintain a constant negative pressure until decontamination of the work area is complete.
The units should not be turned off at the end of the work shift or when removal operations
temporarily stop.
Employees should start removing the asbestos material at a location farthest from the
exhaust units and work toward them. If an electric power failure occurs, removal must stop
immediately and should not resume until power is restored and exhaust units are operating
again.
Because airborne asbestos fibers are microscopic in size and tend to remain in suspension for
a long time, the exhaust units must keep operating throughout the entire removal and
decontamination processes. To ensure continuous operation, a spare unit should be available.
After asbestos removal equipment has been moved from the work area, the plastic sheeting
has been cleaned, and all surfaces in the work area have been wet-cleaned, the exhaust units
can be allowed to run for at least another 4 hours to remove airborne fibers that may have
been generated during wet removal and cleanup and to purge the work area with clean
makeup air. The units may be allowed to run for a longer time after decontamination,
particularly if dry or only partially wetted asbestos material was encountered during removal.
F.3.2.2.1 Filter Replacement
All filters must be accessible from the work area or "contaminated" side of the barrier. Thus,
personnel responsible for changing filters while the negative pressure system is in use should
wear approved respirators and other protective equipment. The operating life of a HEPA filter
depends on the level of paniculate contamination in the environment in which it is used.
During use, filters will become loaded with dust, which increases resistance to air flow and
diminishes the air-handling capacity of the unit. The difference in pressure drop across the
filters between "clean" and "loaded" conditions (AP) is a convenient means of estimating the
extent of air-flow resistance and determining when the filters should be replaced.
When AP across the filters (as determined by the Magnehelic gauge or manometer on the
unit) exceeds 1.0 inch of H20, the prefilter should be replaced first. The prefilter, which fan
suction will generally hold in place on the intake grill, should be removed with the unit
running by carefully rolling or folding in its sides. Any dust dislodged from the prefilter during
removal will be collected on the intermediate filter. The used prefilter should be placed inside
a plastic bag, sealed and labeled, and disposed of as asbestos waste. A new prefilter is then
placed on the intake grill. Filters for prefiltration applications may be purchased as individual
precut panels or in a roll of specified width that must be cut to size.
If the AP still exceeds 1.0 inch of H2O after the prefilter has been replaced, the intermediate
filter is replaced. With the unit operating, the prefilter should be removed, the intake grill or
filter access opened, and the intermediate filter removed. Any dust dislodged from the
intermediate filter during removal will be collected on the HEPA filter. The used intermediate
filter should be placed in a scalable plastic bag (appropriately labeled) and disposed of as
asbestos waste. A new replacement filter is then installed and the grill or access closed.
Finally, the prefilter on the intake grill should be replaced.
F-7
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The HEPA filter should be replaced if prefilter and/or intermediate filter replacement does not
restore the pressure drop across the filters to its original clean resistance reading or if the
HEPA filter becomes damaged. The exhaust unit is shut off to replace the HEPA filter, which
requires removing the prefilter first, then opening the intake grill or filter access, and finally
removing the HEPA filter from the unit. Used HEPA filters should be placed in a scalable
plastic bag (appropriately labeled) and disposed of as asbestos waste. A new HEPA filter
(structurally identical to the original filter) should then be installed. The intake grill and
intermediate filter should be put back in place, the unit turned on, and the prefilter positioned
on the intake grill. Whenever the HEPA filter is replaced, the prefilter and intermediate filter
should also be replaced.
When several exhaust units are used to ventilate a work area, any air movement through an
inactive unit during the HEPA filter replacement will be into the work area. Thus, the risk of
asbestos fiber release to the outside environment is controlled.
Any filters used in the system may be replaced more frequently than the pressure drop across
the filters indicates is necessary. Prefilters, for example, may be replaced two to four times a
day or when accumulations of particulate matter become visible. Intermediate filters must be
replaced once every day or so, and the HEPA filter may be replaced at the beginning of each
new project. (Used HEPA filters must be disposed of as asbestos-containing waste.) Condi-
tions in the work area dictate the frequency of filter changes. In a work area where fiber
release is effectively controlled by thorough wetting and good work practices, fewer filter
changes may be required than in work areas where the removal process is not well controlled.
It should also be noted that the collection efficiency of a filter generally improves as
particulate accumulates on it. Thus, filters can be used effectively until resistance (as a result
of excessive particulate loading) diminishes the exhaust capacity of the unit.
F.3.2.3 Dismantling the System
When a final inspection and the results of final air tests indicate that the area has been
decontaminated, all filters of the exhaust units should be removed and disposed of properly
and the units shut off. The remaining barriers between contaminated and clean areas and all
seals on openings into the work area and fixtures may be removed and disposed of as
contaminated waste. A final check should be made to be sure that no dust or debris remain on
surfaces as a result of dismantling operations.
F-8
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Appendix G. Estimation of Fiber Detection Limit Using
the NIOSH Membrane Filter Method (P&CAM 239}
The NIOSH Membrane Filter Method for measuring airborne fibers is used to determine
compliance with the OSHA exposure standard for asbestos. The lowest level at which fibers
can be reliably detected (detection limit) is reported to be 0.1 fibers per cubic centimeter.*
However, the detection limit depends on total volume of air sampled and decreases as the
volume increases. For uses of this method other than determining compliance with OSHA, a
detection limit should be calculated in conjunction with specifying a sampling time and a
sampling rate.
Based on a study of counting fibers with phase contrast microscopy, NIOSH has specified that
at least 10 fibers must be observed in 100 microscopic fields.f The lower detection limit
(expressed in fibers per cubic centimeter) can be calculated from this value as follows:
DL= [(10 fibers/100 fields)/V] (FA/MFA) (1 liter/1,000 cm3)
where:
DL = detection limit in fibers/cubic centimeter
V = volume of air sampled in liters
FA = effective collecting area of the filter in square millimeters (typically 855 mm2)
MFA = microscopic field area in square millimeters (typically 0.003-0.006 mm2)
For a sampling time of 8 hours at a rate of 2 liters per minute, the V is 960 liters and,
assuming FA is 855 and MFA is 0.003 square millimeters, the DL is approximately 0.03 fibers
per cubic centimeter:
V = (2 liters/min) (60 min/hour) (8 hours) = 960 liters
(10 fibers/100 fieldsX / 855 mmVfilter \ / 1 liter \
960 liters/filter )l 0.003 mm2/field H1,000 cm3 /
DL = 0.0297 fibers/cm3
Because of differences between microscopes, the size of field of view may vary. Most
microscopes have an MFA at the 100 x magnification between 0.003 and 0.006 mm2. For an
MFA of 0.006 mm2, the DL in the above example would be 0.0148 fibers/cm3.
The effective collecting area will also vary with the filter size. The FA is 855 mm2 for a 37 mm
filter.
*Leidel NA, Boyer SG, Zumwalde RD, Busch KA. February 1979. USPHS/NIOSH Membrane Filter
Method for Evaluating Airborne Asbestos Fiber. Washington, DC: National Institute of Occupational
Safety and Health.
tThe coefficient of variation (standard deviation divided by the mean) is reported to be 41 percent when
counting an average of 10 fibers per 100 fields. (Leidel, op cit.)
G-1
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Asbestos
Cementitious
Delaminate
(Human) Exposure
(Material) Exposure
Fibrous
Friable
Homogeneous
Peak levels
Prevalent levels
Resolve
Risk
Appendix H. Glossary
A group of naturally occurring minerals that separate into fibers.
There are six asbestos minerals used commercially: Chrysotile,
Amosite, Crocidolite, Anthophyllite, Tremolite, and Actinolite.
Friable materials that are densely packed and nonfibrous.
To separate into layers. As used here, to separate from the
substrate.
The presence of people in an area where levels of an airborne
contaminant are elevated. A more technical definition sometimes
found in scientific literature is: The total amount of airborne
contaminant inhaled by a person, typically approximated by the
product of concentration and duration.
The amount or fraction of material visible.
Spongy, fluffy, composed of long strands of fibers.
Capable of being crumbled, pulverized, or reduced to powder by
hand pressure.
Similar in appearance and texture.
Levels of airborne containment which are much higher than
average and occur for short periods of time in response to sudden
release of the contaminant.
Levels of airborne contaminant occurring under normal conditions.
To distinguish different objects with a microscope.
The likelihood of developing a disease as a result of exposure to a
contaminant.
H-1
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30272 -101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA 560/5-83-002
4. Title and Subtitle
Guidance for Controlling Friable Asbestos-Containing
Materials in Buildings
3. Recipient's Accession No
5. Report Date
March 1983
7. Author(s)
8. Performing Organization Rept. No
DALE L. KEYES, BERTRAM P. PRICE
9. Performing Organization Name and Address
BATTELLE MEMORIAL INSTITUTE
Columbus Division
2030 M Street, N. W.
Washington, D. C. 20036
10. Proiect/Task/Work Unit No
11. Contract(C) or GranUG) No
68-01-5915
68-01-6721
(G)
12. Sponsoring Organization Name and Address
13. Type of Report & Period Covered
Environmental Protection Agency
Office of Pesticides and Toxic Substances
Washington, D. C. 20460
15. Supplementary Notes
This report was prepared for The Exposure Evaluation Division of The Office
of Toxic Substances. Questions about information in the document should be
directed to Joe Breen or Cindy Stroup (202)382-3569/3891.
16. Abstract (L.mit: 200 words)
This document provides information that supplements previous EPA guidance
on controlling asbestos-containing materials found in buildings. The docu-
ment (1) provides a current summary of data on exposure to airborne
asbestos, (2) identifies organizational and procedural issues in establish-
ing an asbestos control program, (3) reviews technical issues confronted
when assessing the potential for exposure to airborne asbestos in particular
indoor settings, (4) summarizes and updates information on applicability,
effectiveness, and relative costs of alternative remedial actions, (5)
suggests a structured process for selecting a particular course of action
given information on exposure levels, assessment methods, and abatement
techniques, (6) introduces and discusses criteria for determining successful
asbestos control. The material presented is a summary of information and
experience gained over the 4 years since previous guidance was published.
17. Document Analysis a. Descriptors
b. Identifiers/Open-Ended Terms
Airborne Asbestos
Asbestos Abatement
Asbestos-Containing Materials
Asbestos Control Program
Asbestos Exposure
c. COS.'TI F.elc/G.C'Jp
18. Availability Statement
19. Security Class (This Report)
21. No. of Pages
', 20. Security Class (This Page)
(See ANSI-239.18)
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
, U S GOVERNMENT PRINTING OFFICE 1984 447-487/18814
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