ASSESSMENT OF ASSAY METHODS
FOR EVALUATING ASBESTOS
ABATEMENT TECHNOLOGY
AT THE
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
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EP1.2
AAM
ASSESSMENT OF ASSAY METHODS
FOR EVALUATING ASBESTOS
ABATEMENT TECHNOLOGY
AT THE
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
by
PEI Associates, Inc.
Cincinnati, Ohio 45246-0100
Contract No. 68-03-3197
Project Officer
William C. Cain
Manufacturing and Service Industries Branch
Water Engineering Research Laboratory
Cincinnati, Ohio 4526B
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
The information in this document has been funded wholly or in part by
the United States Environmental Protection Agency under Contract No. 68-03-
3197 to PEI Associates, Inc. It has been subject to the Agency’s peer and
administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or corm ercial products does not constitute
endorsement or recomendation for use.
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with
protecting the Nation’s land, air, and water systems. Under a mandate of
national environmental laws, the agency strives to formulate and implement
actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. The Clean Water Act,
the Safe Drinking Water Act, and the Toxic Substances Control Act are three
of the major congressional laws that provide the framework for restoring and
maintaining the integrity of our Nation’s water, for preserving and enhancing
the water we drink, and for protecting the environment from toxic substances.
These laws direct the EP to perform research to define our environmental
problems, measure the impacts, and search for solutions.
The Water Engineering Research Laboratory is that component of EPA’s
Research and Development program concerned with preventing, treating, and
managing municipal and industrial wastewater discharges; establishing prac-
tices to control and remove contaminants from drinking water and to prevent
its deterioration during storage and distribution; and assessing the nature
and controllability of releases of toxic substances to the air, water, and
land from manufacturing processes and subsequent product uses. This publica-
tion is one of the products of that research and provides a vital communica-
tion link between the researcher and the user community.
This publication evaluates a particular aspect of assessing the nature
and controllability of releases of toxic substances to the air. Specifical-
ly, it evaluates the sampling and analytical methods for determining the
concentration of asbestos fibers in buildings that have undergone asbestos
abatement. Aggressive and nonaggressive asbestos sampling methods are eval-
uated and compared, and the phase contrast and transmission electron micro-
scopy analytical methods are evaluated and compared.
Francis T. Mayo, Director
Water Engineering Research Laboratory
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ABSTRACT
Two methods were compared for analyzing the condition of a building
after the removal of asbestos—containing materials: Phase contrast micro-
scopy (PCM), the U.S. Environmental Protection Agency’s (EPA’s) current,
nonaggressive sampling method, and transmission electron microscopy (TEM), an
alternative aggressive sampling technique.
Air sampling was conducted at an EPA office building which had undergone
an asbestos abatement program. The aggressive sampling technique revealed
that air—entrainable asbestos remained in work areas after completion of
abatement actions. The ratio of aggressive to nonaggressive PCM fiber concen-
trations was 7.0, whereas this ratio was 3.7 for TEM analyses. Study results
also confirm that under similar sampling conditions, TEM analysis detects
more fibers than PCM because of TEM’s better resolving capability. The ratio
of TEM/PCM concentrations for nonaggressive sampling was 3.0 for ambient
samples and 3.3 for indoor samples; the ratio for aggressive sampling was
about 2. Because the PCM method does not discriminate between asbestos and
other fibers and cannot resolve fibers thinner than about 0.2 Lim, PCM results
may not accurately reflect the true hazard potential.
Study conclusions led to the following recommendations. Although time-
consuming and expensive, TEM should be recommended as the analytical method
of choice for measuring airborne asbestos fiber concentrations for final
clearance testing 0 f work areas after asbestos abatement. A criterion should
be established that defines an acceptable asbestos fiber concentration in
building areas after asbestos abatement, but not until a standardized TEM
protocol and art aggressive sampling procedure are incorporated into asbestos
guidelines. Continued research should focus on the development of a quicker,
less expensive method for monitoring buildings after asbestos abatement and
on more efficient abatement practices.
This report was submitted in fulfillment of Contract No. 68—03-3197 by
PEI Associates, Inc., under the sponsorship of the EPA. This report covers a
period from August 1984 to October 1985, and work was completed as of April
1986.
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Foreword .
Abstract
Figures
Tables
Acknowledgment
1. Introduction .
Background
Objective
Report organization
2. Conclusions
3. Recommendations .
4. Project Description
Site selection
Building description
Abatement program
Monitoring approach
5. Methods of Air Sampling and Analysis
Overview of sampling strategy
Sampling methodology
Methods of analysis
Quality assurance
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6. Results
Air monitoring results . . . . .
Statistical comparisons
References
Appendices
A. Methodology for the measurement of airborne asbestos by trans-
mission electron microscopy - Level II analysis protocol.
B. LIT Research Institute structure analysis data report and
summary table for a representative sample . . . . . . .
C. Statistical method .
D. Comparison of nonaggressive and aggressive sampling results
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COrt TENTS
. .
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FIGURES
Number Page
1 Floor plan of the main CERL building . . 10
2 Asbestos-containing insulation on the ceiling of
Room l46 11
3 Asbestos-containing insulation on the ceiling of the
penthouse 11
4 Photograph of a typical sampling apparatus 15
5 Photograph of the electric power blower used for
aggressive sampling 17
6 Photographs showing aggressive sampling in progress . . . 18
7 TEM asbestos analysis report 23
8 Air sampling data sheet 26
9 Chain-of-custody form 27
10 Results of phase-contrast and transmission-electron
microscopy analyses from nonaggressive (NA) and
aggressive (A) sampling conditions 31
11 Comparison of airborne fiber concentrations 32
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TABLES
Number Page
1 Results of PCM and TEM Analyses . 30
2 Comparison of Nonaggressive and Aggressive Sampling
Results for Postabatement Testing 33
3 Comparison of Sampling Results by Sample Location . . . . 34
4 Summary Comparison of PCM and TEM Analyses of Air Samples
Collected During Nonaggressive and Aggressive Condi—
tions 35
5 Expanded TEM Data From Nonaggressive and Aggressive Sam-
pling Conditions 39
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ACKNOWLEDGMENT
Many individuals and groups have been he pfu1 in conducting this study
and preparing this report. The able direction and guidance provided by Mr.
Roger Wilmoth, Chief, Manufacturing and Service Industries Branch, EPA; Mr.
William Cain, EPA Project Officer; and Mr. Tom Powers of the EPA are sin-
cerely appreciated. The cooperation and assistance from Mr. James C. McCarty,
Kr. Robert Trippel, and other staff members of the Corvallis Environmental
Research Laboratory, are also gratefully acknowledged.
Mr. Robert Aniick served as Project Director and Mr. Mark Karaffa as
Project Manager for PEI Associates. Ms. Ann Crone and Mr. Charles Zimmer
assisted in the preparation of this report.
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SECTION 1
INTRODUCTION
BACKGROUND
The Technical Assistance Program of the Office of Pesticides and Toxic
Substances of the U.S. Environmental Protection Agency (EPA) provides guid-
ance and information on the identification of asbestos-containing materials
in buildings and on the correction of potential asbestos hazards. EPA Guid-
ance Documents contain much of the technical information about asbestos in
nonindustrial settings.’ These documents describe how to establish an
asbestos identification and control program, provide background information
and direction to school officials and building owners on exposure assessment,
and describe how to develop and implement an asbestos abatement program. The
most recent asbestos guidance from EPA not only emphasizes recent experience
and new information on asbestos control, but it also introduces and discusses
criteria for developing an appropriate asbestos control plan.
Considerable scientific uncertainty still surrounds the technical con-
siderations involved in assessing specific abatement actions to reduce the
risk of asbestos exposure. One critical concern among the persons responsi-
ble for a program is how clean the asbestos-abatement contractor leaves a
building (or building area) after removing the asbestos material or after
completing work that coulc have disturbed an asbestos-containing material
(e.g., encapsulation, enclosure, or special maintenance operations). The two
criteria recomended in the version of EPA guidance (1983) that was in effect
at the time of this study for evaluating the adequacy of the cleanup at the
worksite are visual inspection of the worksite and air monitoring after com-
pletion of the project. Visual inspection should detect incomplete removal,
any damage caused by abatement activity, and (most important) the presence of
debris or dust that could contain asbestos as a result of inadequate cleanup
of the work area. Air monitoring by the membrane filter collection technique
and phase-contrast microscopic (PCM) analysis are recommended to supplement
the visual inspection and to determine whether elevated levels of airborne
fibers generated during the removal process have been sufficiently reduced.
This currently recommended optical microscopic technique, one of two methods
specified by the National Institute for Occupational Safety and Health
(NIOSH) for determining airborne fiber concentrations, is used by the Occupa-
tional Safety arid Health Administration (OSHA) for measurement of total
airborne fibers in occupational environments.
The EPA-recommended air-monitoring methodology for determining abatement
completion (NIOSH Method No. P&CAN 239) was as follows:
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Air sampling should begin after the project has been completed and all
surfaces in the abatement site have been cleaned, preferably within 48
hours after abatement work is finished. A minimum of three air monitors
per worksite and at least one per room is recommended. Air is drawn
through a membrane filter for about 8 hours at a flow rate of approxi-
nately 2 liters per minute. A total air volume of approximately 1,000
liters collected at the specified flow rate should be sampled. After
the sampling, a section of the filter is mounted on a microscope slide
and treated to form a transparent, optically homogenous gel. The fibers
are sized and counted by using a phase—contrast microscope at 400 to
450X magnification. For counting purposes, a fiber is defined as a
particle with a physical dimension longer than 5 micrometers and a
length—to-diameter ratio of 3 to I or greater. 3
This method is intended to give an index of the airborne concentration of
asbestos fibers of specified dimensional characteristics in an atmosphere
known or suspected to contain asbestos. It is not designed to count fibers
less than 5 micrometers long or to differentiate asbestos fibers from other
fibrous particulates.
The most significant limitation of the PCM method compared with the use
of transmission electron microscopy (TEM) and scanning electron microscopy
(SEM) is that the PCM method is limited in detecting fine particles (i.e.,
particles with subinicron diameters, or lengths less than 5 urn) that are
potentially toxicologically significant. For example, in glove-box tests of
simulated industrial mechanical operations on asbestos-containing products
(drilling, sawing, and sanding), the PCM methodology counted less than one
percent of the fibers counted by TEM. 5 Although conditions of this glove box
study are obviously different from asbestos-abatement activities, some con-
cern existed about the relative merits and capabilities of the different
analytical methods used to determine representative fiber concentrations. In
another study, it was estimated that 50 to 100 times smaller asbestos fibers
(i.e., fibers less than 0.2 jim wide and 5 jim long that are not detected by
the PCM method) are present than the larger, optically visible fibers. 6
The conditions in a work area during the time the final air samples are
collected can influence the results of a post-abatement assessment. After an
abatement action, the air is sampled while the area is sealed off, before
ventilation is restored, and usually after at least a 24-hour settling period
following the final wet cleaning. Consequently, this monitoring technique
may not detect residual fibers that were missed by the cleaning or that have
settled on horizontal surfaces during this static condition.
Residual asbestos fibers constitute a potential exposure hazard because
they could be reentrained later when the air in the area is agitated by per-
sonnel traffic, air flow from ventilation systems, and custodial activities.
Thus for more accurate characterization of postabatement fiber concer tra-
tions, the work area should have appreciable air movement, simulating actual
use conditions while air monitoring is being conducted, to determine whether
any reentrainable asbestos fibers remain in the area after completion of
abatement activities. This introduction of air turbulence into the work area
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during the collection of stationary air samples is termed “aggressive sam-
pling.” This method entails the creation of air movement by the use of
blowers, fans, brooms, or compressed air streams to entrain any particulate
matter that may be present. Air sampling methods are further described in
Section 5. The advantage of the aggressive sampling technique over the
static (or nonaggressive) sampling is that the former reflects worst—case
conditions and the testing requires a relatively short period. The disadvan-
tages are that this technique is not readily standardized or reproducible,
nor does it reflect normal exposure levels to occupants. As with the non-
aggressive sampling method, no criteria have been established to define an
acceptable or “safe” level of fibers in a nonoccupational environment.
“Guidance for Controlling Asbestos—Containing Materials in Buildings,” 4
issued by EPA in July 1985, recommends aggressive sampling and TEM analysis
of air samples taken after an abatement action. These new guidelines contain
a recommended protocol for aggressive sampling, a sampling strategy for post-
abatement clearance monitoring, and a statistical method for evaluating the
TEM results and the adequacy of the contractor’s cleanup.
OBJECT! VE
This study posed a problem-defining task designed to assess the adequacy
of EPA’s currently recommended optical microscopic method of analysis and
sample collection technique compared with an electron microscopic method
(TEM) and an alternative aggressive sampling technique. The results of this
study will help to evaluate the advantages and/or technical limitations that
could affect the application of the TEM analytical method and aggressive
sampling technique in the assessment of air quality following asbestos abate-
ment operations. In addition, the establishment of reliable methods of air
sampling and analysis will permit the use of postabatement monitoring results
to evaluate the efficacy of the methods for asbestos abatement and to develop
better technical guidance for abatement contractors, building owners, and
other parties directly responsible for remedial asbestos programs.
Because of the problem—defining nature of the study, the schedule and
limited funding for this task did not allow for the development and implemen-
tation of a quality assurance project plan, which normally precedes such a
field study. Active or recently completed abatement sites were selected for
monitoring in this problem-defining study because they provided an excellent
opportunity to collect real—world data and because the monitoring tasks could
be arranged with minimum lead time and coordination.
REPORT ORGANiZATION
Section 2 of this report presents the study’s conclusions, and Section 3
presents the recommendations. Section 4 describes the site selection crite-
ria, sampling site, abatement program, and monitoring approach. Section 5
describes the nonaggressive and aggressive sampling procedures and the PCM
and TEM methods used to analyze the filter samples collected at this site.
Section 6 presents the air monitoring data, discusses their significance, and
describes the statistical methods used for comparing the monitoring results.
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SECTION 2
CONCLUSIONS
The following conclusions resulted from this study:
1. The aggressive sampling technique used in this problem-definition
study revealed that air—entrainable asbestos fibers were present in
previously abated areas. TEM analysis of ag9ressive samples from
building areas that were never treated with asbestos insulation
also revealed detectable levels of asbestos fibers. The levels
found in the abated areas were not significantly higher than those
in other areas of the building that had never been treated with
asbestos material. These results suggest that 1) the abatement
efforts had reduced asbestos fiber levels to an ‘equilibrium” level
(i.e., fiber concentrations in the abated areas were the same as in
other building areas), or 2) untreated building areas have been
“contaminated to some extent by asbestos from other areas via some
transport mechanism.
2. Regardless of the analytical method used, the concentrations of
fibers measured under aggressive sampling conditions were signifi-
cantly higher than those measured under nonaggressive conditions.
The ratios of aggressive to nonaggressive PCM fiber concentrations
in abated and rionasbestos areas were 7.0 and 8.0, respectively 1
while these ratios by TEfr analysis were 3.7 and 2.0. The PCM fiber
concentrations during aggressive sampling conditions (0.002 to
0.057 fiber/cm 3 ) were well below the NJOSH-recommended occupational
limit of 0.1 fiber/cm 3 , an 8—hour, time-weighted average that is
frequently cited in abatement contractor specifications as the
final, post-abatement acceptance criterion. Alternatively, accord-
ing to the 1983 EPA guidance document, 3 the lower detection limit
was recommended as a standard for releasing the abatement contrac-
tor. The detection limit for a typical 1000-liter air sample ana-
lyzed by the NIOSH P&CAM 239 method would be about 0.03 fiber/cm 3 .
The most recent EPA guidance (1985) now recommends that all PCM
saniple analyses collected under aggressive conditions be less than
0.01 fiber/cm 3 and that the testing parameters be sufficient for
reliable detection of such low levels. Thus, the PCM concentra-
tions measured in the abated areas at this site during aggressive
conditions exceed the EPA criteria for clearance monitoring. Under
nonaggressive conditions, the PCM fiber concentrations in the
abated work areas are all less than 0.01 fiber/cm 3 and thus would
have met the former nonaggressive criterion.
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3. The results of the study clearly demonstrate that, under similar
sampling conditions, TEM analysis identifies more fibers than PCM.
(The ratio of TEM/PCM fiber concentrations for nonaggressive sam-
pling was 3.0 for ambient samples, 7.5 for indoor nonasbestos
areas, and 3.3 for indoor abated samples; the ratios for aggressive
sampling in indoor areas were about 2.) The PCM counting protocol
specifies that only fibers 5 um or longer are to be recorded.
Because only fibers thicker than about 0.2 urn can be resolved by
the light microscope, regardless of their lengths, thin fibers on
the filter may not be detected or recorded by PCM. The TEN dimen-
sional analysis reports on samples taken at the Corvallis site
revealed that many of the asbestos fibers identified on the filters
have widths less than 0.2 um and lengths less than 5 vu ’.
In addition, the PCM method does not discriminate between asbestos
fibers and any other types of fibrous particulate. Thus, the value
obtained from an environmental (nonoccupational) sample analyzed by
only PCM may be totally unrelated to the presence or absence of any
asbestos fibers. After an asbestos-removal project, any fibers
left in the work area might reasonably be expected to be asbestos;
however, it is not unusual for asbestos-containing building mate-
rials to contain other fibrous components, such as mineral wool,
cellulose, or fibrous glass. Thus, the fibers detected by PCN
after an abatement action are not always asbestos and may not
accurately reflect the true hazard potential.
4. Concentrations of asbestos fibers in abated areas (as determined by
TEN), measured by the aggressive sampling method, were significant-
ly (6.2 times) higher than ambient TEM concentrations. The TEM
concentrations under aggressive conditions in the nonasbestos areas
were 5 times higher than ambient TEM concentrations; however, this
difference was not statistically significant. The actual environ-
mental conditions that exist in a building after reoccupancy, reac-
tivation of ventilation systems, and the return to typical usage
patterns are somewhere between the nonaggressive and aggressive
sampling conditions. it is not likely that indoor conditions would
ever be as rigorous as those created during the aggressive sampling
conditions for this project. In addition, finishes applied during
renovation of the building’s interior subsequent to abatement
(e.g., paint, carpeting, and suspended ceiling system), repeated
cleanings, and continuous dilution of indoor air with ambient air
would be expected to further reduce the possibility of residual fi-
ber reentrainment and result in lower indoor concentrations. Over
time, these concentrations would be expected to approach ambient
levels. No data were obtained during this project to verify this
theory.
In summary, this study, which was essentially completed before issuance
of the 1985 EPA guidelines (Purple Book),’ was designed to evaluate the meth-
ods of air sampling and analysis in the 1983 EPA guidance document. 3 The
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conclusions presented in this report, which were based on actual air monitor-
ing data from a large-scale asbestos—abatement project, support the recomnien-
dations for aggressive air sampling and TEM analysis for post-abatement air
quality evaluations presented in the latest EPA guidance docunient.
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SECTION 3
RECOMMENDATIONS
Based on the findings of this study, the following recommendations are
made:
1. TEM should be recommended as the analytical method of choice for
measuring airborne asbestos fiber concentrations for final clear-
ance testing in atmospheres of buildings that have undergone as-
bestos abatement. The current TEM protocols, however, are very
time—consuming and expensive for routine use in large abatement
projects.
2. PCM analyses should be conducted as a preliminary check to deter-
mine whether additional cleanings are necessary before final clear-
ance testing by TEM because PCM analyses are relatively inexpensive
and can be performed quickly.
3. A criterion should be established that defines an acceptable asbes-
tos fiber concentration in building areas after asbestos abatement,
but not until a standardized TEM protocol and an aggressive Sam-
pling procedure have been developed and validated. Once developed,
these methods should be required for all postabatement assessments.
4. Research should continue in the areas of asbestos measurement, sam-
pling, hazard assessment, and abatement control technology so that
asbestos hazards in buildings can be effectively reduced. One iiii-
portant research avenue should be the development of quicker, less
expensive methods for monitoring the atmosphere in buildings after
asbestos abatement.
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SECTION 4
PROJECT DESCRIPTION
SITE SELECTION
Air monitoring was conducted at two sites where friable asbestos build-
ing materials had been removed:
Site 1. Columbus East High School
230 South Marr Road
Columbus, Indiana
Site 2. U.S. EPA Corvallis Environmental Research Laboratory
200 S.W. 35th Street
Corvallis, Oregon
This report describes only the results of the air monitoring survey
conducted at Site 2. The monitoring data from Site 1 and the significance of
these data are the subject of a separate report. The sites selected met the
following criteria:
o The abatement plan involved the removal of friable, spray—applied,
asbestos-containing material.
O The contractors carried Out the work area preparation, removal, and
decontamination in accordance with EPA—recommended specifications
and requirements. 1
o Multiple work areas containing homogeneous asbestos material were
available for monitoring.
O The building owner and abatement contractor agreed to cooperate
with EPA and to provide access to selected areas of the building.
The EPA Laboratory site was made available for this work as a result of
collaborative agreement between the EPA Project Officer and the CERL Direc-
tor, who had expressed interest in participating in this study.
BUILDING DESCRIPTION
The Corvallis Environmental Research Laboratory (CERL) is housed in a
two-story, reinforced—concrete structure built in 1966. The building con-
tains a total gross area of approximately 45,000 ft 2 (465 rn2). A single-pass
HVAC system supplies the occupied building areas with 100 percent outside
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air. The outside air enters through intakes on the roof 1 is tempered by
heating or chilling coils, and is distributed by a closed—duct system to
ceiling-mounted diffusers in all rooms and laboratories. Air flows through
louvers in the bottom of interior doors and passes into the hallways (which
serve as air plenums to the outside) or is exhausted through laboratory fume
hoods. Figure 1 shows the floor plan of the main CERL facility.
Asbestos-containing Materials
Asbestos-containing insulation had been spray-applied and tamped on the
concrete ceilings (beams and deck) of four rooms (Rooms 146, 155, 157, and
159) and the penthouse in the main CERL facility and on beams in the boiler
room (Room 163). The large air intakes located under the building, which
supply ventilating air to the boiler and chiller room, were also lined with
asbestos. The insulation material on the ceilings of Rooms 155, 157, and 159
and in the air ducts was removed in 1984 during a controlled abatement pro-
gram. The asbestos-containing insulation in Room 146 (deionizer room), the
boiler room, and the penthouse is still in place.
Samples collected from Room 146 and the penthouse were analyzed by
polarized light microscopy and dispersion staining. The results indicated 80
percent amosite asbestos in each of the two bulk samples analyzed. At the
time of the survey, the remaining insulation material was characterized as
highly friable, loosely packed, and showing some signs of deterioration
(loose, hanging pieces visible). Refer to Figures 2 and 3.
ABATEMENT PROGRAM
The asbestos—containing insulation in Rooms 155, 157, and 159 and in the
air intakes was removed between May 21 and July 2, 1984. The abatement plan
and schedule prepared by the contractor and submitted to CERL were reviewed
and approved by EPA before work was begun. The work plan was in accordance
with the EPA guidelines and EPA and OSHA asbestos regulations for asbestos
removal and decontamination in effect at the time. Upon completion of the
abatement effort, CERL personnel surveyed the work performed by the abatement
contractor, performed additional clearing of the work areas, and made arrange-
ments for the painting of all ceiling surfaces from which the asbestos insula-
tion had been removed.
According to CERL accounts, each work area was isolated from the rest of
the building by temporary barriers. Ventilation ducts and openings to the
outside or to adjacent rooms were sealed. Walls and floors were covered with
plastic sheeting. Fully protected abatement workers first wetted the insula-
tion with amended water and then scraped it off. The asbestos-containing
debris was placed in sealable plastic bags and disposed of at a local EPA-
approved sanitary landfill. Each work area was repeatedly wet-cleaned, and a
settling period was allowed between cleanings. The ceiling surfaces were
painted to bond any residual fibers that may have not been removed by the
scraping, brushing, and wet-cleaning.
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Figure 1. Floor plan of the main CERL building.
MAIN BUILDING, FIRST FLOOR
MAIN BUILDING. SECOND FLOOR
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Figure 3. Asbestos-containing insulation on the
ceiling of the penthouse.
Figure 2. Asbestos-containing insulation on the
ceiling of Room 146.
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MONITORING APPROACH
The sampling strategy for this study was to collect representative PCM
and TEM samples 1) in rooms where friable asbestos-containing insulation had
been removed, 2) in rooms that were never treated with asbestos-containing
materials, and 3) outdoors. Samples for subsequent PCM and TEll analyses were
collected from two or three representative locations in each room approxi-
mately 6 weeks after completion of all abatement activities. Two of the
three monitored rooms from which asbestos insulation had been removed had
been reoccupied. (Room 159 was vacant at the time of the survey.) Both
nonaggressive and aggressive sampling techniques were used in each room. The
nonaggressive or static sampling was conducted first, followed by the aggres-
sive sampling. The nonaggressive sampling was performed on a weekday during
regular working hours while the facility was in use and occupied. The ag-
gressive sampling was conducted on a Saturday when the sampling areas were
unoccupied. (The sampling procedures and analytical methods used in this
study are described fully in Section 5 of this report.) To sumarize brief-
ly, filter holders containing either 0.8-pm Mhllipore mixed-cellulose ester
(PCM) or 0.4-pin Nuclepore polycarbonate filters (TEM) were positioned 4 to 5
feet above the floor at arbitrary locations. Battery—powered sampling pumps
were used to draw air through the filters. The constant-flow pumps were
calibrated to 2.5 liters per minute and were operated for 8 hours per test.
Samples were collected concurrently at outdoor locations during each monitor-
ing period.
Upon completion of each monitoring survey, samples were submitted to the
appropriate laboratory for preparation or analysis. The Nuclepore filters
were carbon—coated before they were transported to the laboratory for TEM
analysis.
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SECTION 5
METHODS OF AIR SAMPLING AND ANALYSIS
OVERVIEW OF SAMPLING STRATEGY
Samples designated for PCM and TEM analysis were collected both ag-
gressively and nonaggressively in six different rooms. Samples were also
collected in the surrounding environment outside the building. The areas
sampled included three rooms that had been treated previously with asbestos
insulation and have since been abated, and rooms that have never been treated
with asbestos. Representative PCM and TEll samples were collected approxi-
mately six weeks after all abatement activities had been completed. Outdoor
air samples were collected on the roof of the building or at ground level in
the open field west of the main building concurrently with the indoor sam-
ples.
Side-by-side (one PCM, one TEll) samples were collected in each room
under nonaggressive and aggressive sampling conditions. The number of sam-
ples per room was not specified by study design; however, three of each type
of sample were collected within each room. The nonaggressive sampling was
performed first, during regular working hours with the building occupied and
the HVAC system operating. The aggressive sampling was performed on a Satur-
day while the sampling areas were unoccupied and the HVAC system was not
operating. Placement of the sampling equipment within each work area was the
same during both nonaggressive and aggressive sampling.
SAMPLING METHODOLOGY
Sampling EQui pment
Samples for subsequent PCM analysis were collected on 37-mm Millipore
Type AA, mixed-cellulose ester membrane filters (0.8—pm pore size). The
filters were preassembled by the manufacturer in three—stage polystyrene
cassettes. Samples for TEll analysis were collected on 37-mm Nuclepore poly-
carbonate membrane filters (0.4-pm pore size). The polycarbonate membrane
filter was supported within a three—stage polystyrene cassette by means of a
support pad and backup filter (mixed-cellulose ester membrane, 5-pm pore
size). Each sample cassette was sealed with a cellulose shrink band to
prevent air from entering the sides of the unit during sampling.
Battery-operated personal sampling pumps equipped with rotameters and/or
constant-flow controls were used to draw air through the sample filters. All
sampling pumps were calibrated before and after sample collection with a
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Magnehelic air flow gauge that had been calibrated by a soap—film flowmeter.
The rotameter setting of each calibrated sampling pump was noted to provide a
visual indication of proper pump functioning, and the settings were checked
periodically throughout the sampling period.
Sample Collection and Handling
Samples designated for both PCM and TEM analyses were collected at a
known flow rate of approximately 2.5 liters per minute (LPM). Sampling
duration was 8 hours. The average sample volume per filter was 1200 liters.
All samples were collected open-faced (i.e., with the face cap of the
cassette device removed) to expose the entire surface area of the filter.
During sampling, the face caps were carefully stored in clean, resealable,
plastic bags. The filter cassettes were positioned at breathing zone height
[ 4.5 to 5.5 feet (1.4 to 1.7 ni) above the floor] and were supported by taping
the end of the sampling hose to the wall or clipping it to an adjustable
tripod. The sample cassettes were also positioned so that the faces of the
membrane filters were angled slightly toward the floor. Figure 4 shows a
typical sampling apparatus.
At the end of the sampling period, each filter cassette was turned
upright (i.e., the filter plane was parallel to the floor), the sampling pump
was turned off, the face cap of the three-stage filter cassette was reposi-
tioned tightly on the cassette, the cassette was disconnected from the sam-
pling hose, a plastic plug was inserted into the cassette outlet, and the
cassette was placed face-up in a box for transport. All PCM and TEM filter
samples were maintained in this upright position from the time of collection
until they were carbon—coated or were analyzed by the appropriate laboratory.
The PCM filters were hand—carried to the PEI Laboratory in Cincinnati, where
they were subsequently analyzed.
The TEM samples were carbon-coated at the Electron Microscope Facility
at Oregon State University in Corvallis and hand—carried to EPA in Cincinnati.
The TE samples were later shipped via overnight courier or hand—carried to
the TEM laboratory in Chicago for analysis.
Nonaggressive Sarnpl ing
Samples for PCM and TEM analyses were collected under nonaggressive
conditions for comparison with similar samples collected under aggressive
conditions. The sampling condition was considered nonaggressive when air
movement in the work area was negligible and/or minimized to the greatest
possible extent. It is postulated that under this condition asbestos fibers
(or any other particulate matter) will “settle out” if given sufficient time.
The probability of reentrainment of these asbestos fibers is much lower
during nonaggressive conditions than during conditions of typical building
use or aggressive sampling conditions. In this study, nonaggressive sampling
conditions existed when the work area was sealed off, all ventilation was
14
-------
Figure 4. Photograph of a typical sampling apparatus. Personal sampling
pump and filter cassette are positioned on ar adjustable tripod.
15
-------
shut off, and personnel access was prohibited. These are the typical condi-
tions under which air monitoring is conducted at a work site following asbes-
tos removal and decontamination.
Aggressive Sampling
Samples for PCM and TEM analyses were also collected under aggressive
sampling conditions. Aggressive conditions were created by introducing air
turbulence into the sampling area by intermittent use of a hand-held electric
blower. The air movement created was much greater than would exist under
conditions of normal building use. Under these aggressive sampling condi-
tions, it is postulated that most asbestos fibers susceptible to entrainment
would become airborne and remain suspended for the duration of the sampling
period, as long as the fans were operated or the hourly introduction of air
turbulence was continued. Thus 1 an aggressive environment provided the best
possible setting for high or “worst-case” airborne asbestos fiber concentra-
tions following abatement.
The blower used in this study was a 1—hp, electric power blower, as
shown in Figure 5 and in the background in Figure 4. The airflow rate at the
blower outlet is approximately 300 ft /min (8.5 m 3 /min). The electric blower
was equipped with a two—piece plastic tube extension and concentrator nozzle
that enabled the operator to direct the airstream at objects and surfaces
within the sampling area.
Aggressive sampling conditions were created in each of the work areas
sampled by an initial “blow-down” of all surfaces, followed by hourly agita-
tion with the blower throughout the duration of the sampling period. During
aggressive sampling, the doors of the rooms were closed and building air
handling systems were shut off. Figure 6 shows photographs of an aggressive
sampling procedure in progress. The sequence of operations is sumarized
below.
1. A technician wearing full-body protective clothing and respiratory
protection entered the work area, positioned the sampling equip-
ment, and started the sampling pumps.
2. Using a back—and—forth motion, the technician directed the air-
stream of the electric blower at all surfaces within the sampling
area (walls; floors; ceilings; all junctures between walls, ceil-
ings, and floors; and any other exposed surfaces within the area
enclosure). The technician then exited the sampling area.
3. After an elapsed time of approximately 1 h6ur, the technician
reentered the room and directed the air steam from the blower back
and forth across the floor for about a minute. This procedure was
repeated hourly for the duration of the sampling period. Unless
actively engaged in manipulating the electric blower or checking
the sampling apparatus, the technician did not remain the room.
16
-------
Figure 5. Photograph of the electric power blower
used for aggressive sampling.
17
-------
. Figure 6. Photographs showing aggressive sampling in progress.
18
-------
4. At the end of the sampling period, samples were collected, sampling
pumps were turned off, and the sampling equipment was removed from
the area.
The technician used appropriate respiratory protection and followed
appropriate decontamination procedures.
METHODS OF ANALYSIS
Phase-Contrast Microscopy
All PCM samples were analyzed in accordance with NIOSH Method No. P&CAM
239. This optical microscopic technique is the method the Occupational
Safety and Health Administration uses to measure total airborne fibers in
occupational environments. The 1983 EPA guidance document pertaining to
asbestos in buildings (which was current at the time this study was con-
ducted) recommends a visual inspection of the worksite, followed by air moni-
toring by the membrane-filter collection technique and phase-contrast micro-
scopic analysis, as one method for evaluating satisfactory completion of
asbestos abatement and decontamination of the worksite. 3
Airborne fiber concentrations were determined by NIOSH Method No. P&CAM
239 through microscopic examination of the fibers collected on a mixed-cellu-
lose ester membrane filter. A triangular wedge comprising approximately
one-eighth of the entire surface area of the 37-mm-diameter filter was removed
from the sample cassette, mounted on a microscope slide, and examined. The
filter wedge was rendered into an optically transparent homogeneous gel by
the use of a slide-mounting solution of 1:1 (by volume) dimethyl phthalate
and diethyl oxalate. A microscope equipped with a phase-contrast condenser
was used to size and count the fibers at 400-450X magnification. Only those
fibers longer than 5 micrometers and having a length-to—width ratio of 3 to 1
or greater were counted. Fibers were sized by comparing fiber length with
the diameters of the calibrated circles of a Porton reticle. Sample analysis
continued until at least 20 fibers or 100 microscopic fields had been counted.
Microscopic field areas generally range from 0.003 to 0.006 mm 2 . The fiber-
counting procedure followed the rules specified in the analytical method.
The estimated average airborne asbestos fiber concentration in the
filter sample is calculated by using the following formula:
AC — [ (FB/FL) - (BFB/BFL)3(ECA )
— (FR)(fl( WA)
where
AC = Airborne fiber concentration in (fibers > 5 zm)/m3
BFB = Total number of fibers counted in the BFL fields of the
blank or control filters in fibers > 5 pm
BFL = Total number of fields counted on the blank or control
filters
19
-------
ECA = Effective collecting area of filter (855 nri 2 for a 37—n
filter with an effective diameter of 33 nui )
FR = Pump flow rate in liters/mm (1PM)
FB = Total number of fibers counted in the
> 5 im
FL = Total number of fields counted on the
MFA = Microscope count field area in nr 2 (a
p 2 was used by the PEI Laboratory)
T = Sample collection time in minutes
The minimum total fiber count in 100 fields that is considered adequate
for reliable quantitation is 10 fibers. Thus, the lower limit of reliable
quantitation for this method is approximately 22,720 fibers/rn 3 (or 0.023
fibers/cm 3 when 1200 liters of air is sampled). During this study, all of
the PCM samples collected under nonaggressive conditions and several of the
PCM samples coUected under aggressive conditions yielded fiber counts less
than the reliab’e quantitation limit (i.e., less than 10 fibers in 100 fields).
The fiber concentrations of these samples were calculated and reported based
on the actual number of asbestos fibers counted rather than merely “less than
the limit of reliable quantitation” because it was believed this would pro-
vide valuable information about these data that otherwise would have been
lost. The precision, accuracy, and coefficient of variation associated with
sample results below the reliable level of quantitation have not been deter-
mined.
Analyses of several other PCM samples collected during this study yielded
counts of zero fibers per 100 fields. Because one-half of one fiber is the
smallest quantity permitted to be counted in the counting rules specified in
P&CAM 239, these sample concentrations are reported as less than the lowest
limit of detection (i.e., the fiber concentration based on counting 1/2 of a
fiber in 100 fields) as shown in the following calculations:
— Number of fibers counted/lOU fields
Detection imit - Volume of air sampled (ni 3 )
Effective collecting area of the filter (m 2 )
X Microscopic field area (nrn 2 /field)
Sample calculation: DL = 0.5 fi er 00 fields
855 m 2 /filter = 1072 fibers/rn 3
0.003136 m /field
Transmission Electron Microscopy
Nuclepore filters were prepared and analyzed for asbestos content by TEM
in accordance with the Methodology for the Measurement of Airborne Asbestos
by Electron Microscopy by Yamate, et al. 8 The current TEM methodology was
developed particularly for application to samples collected from a volume of
FL fields in fibers
filter
field area 0.003136
20
-------
air in which the asbestos concentration is considered a minor component of
the total particulate loading. Carbon-coating of the samples was performed
by the staff of the Electron Microscope Facility at Oregon State University.
Completion of sample preparation and sample analyses were performed by the
TEM laboratory in Chicago.
Three levels of TEM analysis are described in the methodology. Briefly
summarized, Level I TEM analysis involves examination of the particulates
deposited on the sample filter by a 100-kV transmission electron microscope.
Asbestos structures (fibers, bundles, clusters, and matrices) are counted,
sized, and identified as to asbestos type (chrysotile, amphibole, ambiguous,
or no identity) by morphology and by observing the selected area electron
diffraction (SAEO) patterns. The width-to—length ratio of each particle that
is counted is recorded. Level II TEM analysis consists of a Level I analysis
plus chemical elemental identification by energy-dispersive spectrum (EDS)
analysis. Energy—dispersive analysis is used to determine the spectrum of
the X-rays generated by an asbestos structure. X—ray elemental analysis is
used for further categorization of the amphibole fibers, identification of
the ambiguous fibers, and confirmation or validation of chrysotile fibers.
All Nuclepore samples collected in this study were analyzed by Level II TEM.
Level III TEM analysis (not used in this study) consists of a Level II anal-
ysis plus quantitative SAED of individual fibers. Quantitative SAED is a
more extensive SAED analysis than that used for Level II. Fibers are exam-
ined from different orientations or viewing angles and compared with SAED
patterns from asbestos mineral standards in Level III quantitative SAED.
Shortly after sampling was completed, the Nuclepore polycarbonate fil-
ters were carbon-coated. Carbon-coating, the first step in the sample prepa-
ration procedure, is accomplished by removing the face cap from the cassette
holder to expose the surface area of the sample filter and then securing the
open-faced holder to a rotating turntable for carbon—coating within a high-
vacuum carbon evaporator. Once carbon—coated, a 3—mm—diameter section of the
polycarbonate filter (usually midway between the center and edge) is placed
on a 3—nim—diarneter electron microscope grid. The polycarbonate membrane is
then dissolved with solvent, which results in a membrane-free EM grid with
particles embedded in the carbon film coating. An optional step in sample
preparation is gold—coating (accomplished in a manner similar to that for
carbon-coating). The thin gold coating provides an internal standard for
SAED analysis.
The prepared samples were examined with the transmission electron micro-
scope at 20,000X magnification for particulate counting and sizing. A min-
imum of 100 fibrous structures or 20 grid openings, whichever came first,
were examined. (Analytical protocol requires that a minimum of 100 fibrous
structures or 10 grid openings be examined. In this study, 20 grid openings
were examined to lower the detection limit because very low fiber concentra-
tions were expected in these postabatement samples.) The exact counting
rules and sizing techniques are described in greater detail in Appendix A.
In addition to particulate counting and sizing, the SAED patterns from all
fibrous structures identified were observed. From visual examination of the
21
-------
SAED pattern, a fibrous structure can be classified as belonging to one of
four categories: 1) chrysotile, 2) amphibole group (includes amosite, croci-
dolite, anthophyllite, trernolite, and actinolite), 3) ambiguous, or 4) no
identification. The SAEO patterns cannot be identified for all particulates
(particularly matrices/debris, clusters/clumps) because of the absence of a
recognizable diffraction pattern. X-ray el°mental analysis with EDS was used
to categorize the amphibole fibers, to identify the ambiguous fibers, and to
confirm or validate chrysotile fibers. A sample laboratory surmiary analysis
report is shown in Figure 7. The dimensional analysis and EDS results for
this sample are presented in Appendix B.
The fiber concentration of the filter sample is calculated by using the
following equation:
Fiber / Total No. of fibers
5 rn No. of EM fields
Total effective filter area, cm 2
Area of an EM field, cm 2
I
X Volume of air sampled, m 3
The total effective filter area is 8.6 cm 2 . The areas of the grid
openings varied, typically ranging from 0.00005 to 0.00007 cm 2 . The average
grid opening area per sample was calculated and recorded on the laboratory
analysis report.
The theoretical limit of detection for the TEM analyses performed was
based on counting one fiber or structure in 20 grid openings. This limit of
detection is calculated by the following formula:
— 1 fiber Prea of filter (cm2 )
Detection limit of grid X Area of grid opening (cm 2 )
openings scanned
1 — 1 fiber 8.6 cm 2
X Volume of air (m 3 ) — 20 0.63 cm 2
x = 5688 fibers/rn 3
Analyses of two TEM samples collected during this study yielded counts
of zero fibers or structures per 20 grid openings. These samples are re-
ported at less than the detectable limit (as calculated by the aforementioned
equation).
22
-------
TEll Asbestos Analysis Report
Saiiiple 1.D . COR—N31 DS170 Date Analyzed:_7/24/85
Date Sample Received: 4/11/85 Sample iypo.
Filter Type 37 ITri Nuclepore Filtration Area ___________
Plumber of Grid OpenIngs: 20 Plumber of Grids Examined: ______________
Total Area Examined (cm 2 ) .0012412
Coments:
Area Exauinned
No.
13
0
11
2
12 _______________
No. of Asbestos FIbers 10 69,288
lb. of Chrysotile Fibers 0 BDL
No. of Amphibole Fibers 10 69,288
tin, of ltatrix/Dehrls (Asbestos) 0 BDL
Plo. of Cluster/Clumps (Asbestos) 1 6,929
lb. of Bundles (Asbestos) 0 BOL
__________________TITRI Sample lb.: C066100120
Bulk Water llisc. (circle one)
(cm 2 ) 8.6 Volume of Fluid Sampled’ 1150 L
2 Average Area of Grid Opening ( cm 2 ) _ .00006206
Detection Limit: 6,025 asbestos structures per m 3
( J
No. of Fibrous Structures (Total)
110. of Chrysotile Structures
No. of Amphibole Structures
P lo. of OtIler* Structures
lb. of Fibers (Total)
Filtration Area
No.
90,074
B DL **
76,217
13,858
83,145
Ho. /Vol iime
Plo./1 tin /CC
78.3 .08
66.3 .07
120 .01
72.3 .07
60.2
60.2
6.0
* Category of “other” Includes: Amhiguotis, lion-Asbestos, and No E. D. Pattern.
*E OIL Below Detectable Limit.
Coimients: Liaht loadina __________
.06
.06
006
Figure 7. TEll asbestos analysis report.
-------
QUALITY ASSURANCE
The objective of quality assurance activities is to provide quality data
through the use of proper sampling procedures, careful handling of samples,
the use of calibrated analytical equipment and standardized analytical proto-
cols, and the checking of fiber analysis calculations. As standard procedure
for tasks performed under this EPA contract, a comprehensive, wri ten Quality
Assurance Project Plan (QAPP) is prepared and submitted to EPA at least 30
days prior to the performance of any sampling, analyses, or data reductions.
In this instance, however, the abatement schedules at the sites selected for
monitoring and the dates of issuance of this task and work plan approval did
not allow sufficient time for the preparation, review, and approval of a
formal QAPP before the sampling had to begin. As a result, the requirement
for submittal of a written QAPP was waived to take advantage of a unique
opportunity to collect field data from these two readily accessible asbestos—
abatement sites. Under these conditions, the following QA/QC criteria were
incorporated into the scope of this project, and field and laboratory proce-
dures were documented to ensure the integrity of the data generated.
Filter Preparation
All Millipore membrane filters used in the collection of asbestos air
samples were preassembled by the manufacturer in three-piece plastic cas-
settes, and all were from the same production lot number. All the Nuclepore
polycarbonate filters used for sampling also were from the same lot and were
loaded into Millipore filter cassettes (on top of the 5.0-iim mixed—cellulose
ester filter and cellulose backup pad) by laboratory personnel in a remote,
clean area of the laboratory. The monitoring cassettes were reassembled, and
a cellulose shrink band was placed around the base and middle stages of each
cassette. The monitoring cassettes were labeled with a Field Sample ID
Number prior to sampling.
Sampling
Constant-flow and/or rotameter—equipped personal sampling pumps were
used to draw air through the filter/cassette assembly at a known flow rate of
2.5 liters/minute. Each pump was calibrated on site before sampling and
checked after sampling by the use of a Magnehelic air flow gauge. Rotanieters
on the sampling pumps were checked periodically during the sampling period to
ensure the constancy of the flow rate. No flow rate adjustments were re-
quired during the sampling periods.
The sampling strategy was to collect two or three pairs of samples in
each completed work area (each pair consisting of one PCM and one TEM sam-
ple). The filter cassettes were positioned about 5 feet (1.5 m) above the
floor and were supported by taping the end of the hose to the wall or clip-
ping it to a tripod. The sampling locations were determined arbitrarily
rather than randomly. The sampling strategy was to have at least one sam-
pling location in the center of the area and one or two near the perimeter.
24
-------
Field record books were maintained by the onsite field technicians or
supervisor at each sampling site. Air Monitoring Data Sheets (Figure 8) were
used to record the following information for each series of air tests:
O Sampling site
o Date and time
o Location of sampling equipment
° Sample number
o Sample type
° Sampling method
o Sampling parameters (flow rates, start time, stop time, duration)
o Field technicians’ observations
Upon completion of sampling, each filter cassette was turned upright
(i.e., the filter plane was parallel to the floor), the pump was turned off,
the face cap was positioned tightly on the filter cassette, and the cassette
was disconnected from the sampling hose. The filter cassettes were hand—
carried to the appropriate laboratory for analysis or to an intermediate site
for carbon—coating, and then carried or shipped via courier to the analytical
lab.
The Millipore filters for PCM analysis were checked into the laboratory,
where each sample was assigned an alphanumeric identity code. The Nuclepore
samples were submitted to the EPA Project Officer (or his representative) and
later sent to the TEM laboratory.
Chain of Custody
A chain-of—custody form (Figure 9) was filled out in ink for each set of
samples collected in the field. Each form was initiated by the onsite field
technician who collected the samples. The next person having custody of the
samples noted receipt of the samples and completed the appropriate section of
the form. As standard procedure, samples arriving at the PEL laboratory are
checked in by the laboratory sample custodian, who examines the shipping
container and each filter cassette for any evidence of damage or tampering,
notes any damage or indication of tampering on the enclosed chain-of—custody
form, and then signs the form. Once samples are received by the laboratory,
a similar ir tra1aboratory chain-of-custody procedure is maintained so that
the location of the samples and the person having custody are always known.
Sample Analysis
The PCM samples were analyzed in accordance with NIOSH Method No. P&CAM
239. All microscopists performing PCM analyses have successfully completed
NIOSH Course No. 582, Sampling and Evaluating Airborne Asbestos Dust, and
have participated in the NIOSH Proficiency Analytical Testing (PAT) Program.
As part of the American Industrial Hygiene Association’s laboratory accredita-
tion program, the laboratory that conducted the PCM analyses participates in
the NIOSH PAT Program. This program currently includes biomonthly analyses
for asbestos and other occupational contaminants. Known reference standards
(i.e PAT asbestos samples) are routinely analyzed to ensure the accuracy of
25
-------
Sh.et No. _______
Ficility
Address -
city —
AIR SAMPLING DATA SHEET
Figure 8. Air sampling data sheet.
DATE
State
Zip
flow
Samp’e
No.
Location
E ul ent
ype T
rate,
Time
Vo’ume,
flters
Units,
Conc.,
?T
W T
26
-------
SAMPLE SH IPPING/REçEIVING RECORD
1. NAME OF (STABLISP*IENT PN
2 SENDER
Signature
Date
Sent from
3. CARRIER
Company
Signature
Date
B/I No.
4. RECUVER
Courier from Depot
5 lgi ti t
Date
LAB CUSTODIAN
Signature
Date
Condition upon
Receipt
5. SHIPMENT DESCRIPTION
Number of packages
Sealed (yes or no)
Types of containers
Seal No.
Seal
intact’
Seal No
Seal
Intact’
Condition prior to shipment
6 CONTENTS
Sample 1.0. number
Type of
sample
Sealed
(yes or no)
Seal No.
if any
Condition (damaged.
loss of liquid, etc
Figure 9. Chain-of-custody for-rn.
(Sample shipping/receiving record).
27
-------
the PCM results. The results of the analysis of PAT asbestos reference
samples have consistently fallen within the acceptable limits of variation
for the method. A record of the precision of the PCM analysis is generally
kept by calculating the coefficient of variation of the results of replicate
analyses. One sample blank is analyzed for every 10 samples to check the
quality of the filter media and sample preparation procedure.
All data generated by the laboratory and by the field technician during
this task were checked for technical accuracy by the laboratory supervisor or
the certified industrial hygienist. This involved verifying that the mathe-
matical computations were correct and that the appropriate formulae were
used. The laboratory supervisor reported the analytical data in writing to
the project manager.
The standard QA/QC procedures that apply to the Nuclepore samples sub-
mitted for TEM analysis are as defined by IITRI’s QA/QC plan for TEM anal-
ys is.
28
-------
SECTION 6
RESULT S
AIR MONITORING RESULTS
Table 1 presents a detailed listing of the results of PCM and TEM anal-
ysis of samples collected during aggressive and nonaggressive sampling condi-
tions after abatement. With one exception, all concentrations of asbestos
fibers and total structures under aggressive sampling conditions were higher
than the corresponding measurements made under nonagyressive sampling condi-
tions. Only one PCM sample collected under nonaggressive sampling conditions
(Sample No. COR-02) had a fiber concentration that was higher than the corre-
sponding PCM aggressive sample (Sample No. COR—27). The difference between
these two samples (0.007 versus 0.002 fibers/rn 3 ) is considered negligible
because both sample results were below the limit of reliable quantitation for
the analytical method. Figure 10 presents a sumarized version of the air
monitoring data on a floor plan of the building in which the samples were
collected.
Comparisons of the results of PCM and TEM analyses of samples collected
during nonaggressive and aggressive sampling conditions are presented graphi-
cally n Figure 11, which is based on the data results presented in Table I.
STATISTICAL COMPARISONS
Statistical Method of Analysis
The Mann-Whitney test was used to determine whether the observed dif-
ferences in analytical methods, sampled areas, and sampling conditions iere
statl5tically significant. 9 Use of the Mann—Whitney test required no a
priori assumption regarding the nature of the underlying probability ths-
tribution function of measurements of asbestos fiber concentrations. A
detailed discussion of the Mann-Whitney test and an example of its applica-
tion are presented in Appendix C.
Analytical Methods
Tables 2 and 3 present comparisons between the geometric averages of
fiber concentrations determined by PCM and TEM analyses under noriaggressive
and aggressive sampling conditions. Table 4 presents a suimiary of these re-
sults. Based on the application of the Mann-Whitney test and the assumption
that the °fiber”/volunie concentrations are comparable, the difference between
PCM and TEN results is statistically significant (i.e., p c 0.03) for samples
collected outdoors and indoors in abated areas under nonaggressive conditions.
29
-------
TABLE 1. RESULTS OF PCM & TE l l ANALYSES
Sioulvog local ion
NOinay gr ossire
Aygrs-ssi .r
°(N
I ON
0 ( 0
It O
Sample 10’ asbrstosa 10’
luster fibers/u’ structures/u 1
Sample
,nfler
io fibers/c’
5aoiple
ni er
10 asbettosa
tibeesfm’
iO asbestos ’
strud turns / r n 1
SuopIr
nuberr
I0 fib.. rs/m’
Abated si-tam
0 c c . 155
CON-C?
(00-03
C0R-O1
0 (p3fC
1437 C
cO
(00-N-C?
(00-0-03
CO O-SI-Cl
0 006
0 016
0 0 )0
0 006
0 0 )6
0 0 )0
(06-71
(0 6- 75
(0 8-70
0 W(
0 01
0 Od?
COO-N- ??
COO-h-PS
C0O-ii-76
0 31?
0 041
0 021
0 022
0 041
0 074
Rota 15?
COO-OO
(00-05
(00-04
0 O0fi
0 0O
0 01
(00-0-04
COO-ai-05
(00- 0-06
0 018
0 OI l
0012
0 020
0 01?
0012
(00-20
(00-29
(00-30
0 032
0 040
0 035
C00-ii-28
(00- 1 1-79
(00-0-30
0 0.41
0 lO S
0 059
0 Oil
0 104
0065
Roe. 159
(Q6 Q
(00-07
(00-09
.Q
.0
0 (0l
(00-0-00
COO-N-OP
COO-N-GO
.0
0 036
0011
.0 0050
0 006
0 III
(00-3)
(00-46
C00-34
0 045
0 045
0 057
C0I-N-31
COO-I-lb
(00-0-34
0 063
0 025
0 022
(1 046
0 075
0 078
Nonatbestos areas
Room 113
(00-13
COO-Il
-0
C 002
(04-0-13
(OO-o-I0
0 OIl
f
0 O I l
f
(00-35
(00-36
0 Oll
0 ( 43 )C
(00-0-35
(00-0-36
0 006
f
0006
f
Room 152
COO-IC
(00-16
.0 W2
0 1432
(00-0-30
COO-N-IS
0 032
f
0 0 )2
f
(0 6-37
COO- 38
0 I?
0 1$
(00-4-32
(00-N-3d
0 235
f
0 249
Room 205
(00-19
COO-Il
COO-I ?
vO OO2
.0 (02
0 WS
COO-N-lA
COO-N-Il
COO-N-Il
0 024
F
f
0 024
f
F
(06-40
COO- 39
(00-4 1
0 0 1 C
0 00(
00)
(09-0-40
COR-N-39
(04-9-42
0 032
f
f
0 037
f
i
Orntttors (atient)
Ground
(00-21
(0 0-44
.0 002 (1
-O 002
(00-1-21
(00-9-44
‘0 0CC
F
‘0 000 e
F
Roof
(00-03
COO-l B
(00-42
.0 oo
.0 032
.0 002
C00-H-43
C0O-o-lO
(00- 0-33
0 011
F
F
0 011
F
I
Blanks
COO-IS
COO-I?
CO O-lB
(06-49
0/i00
0/I30
0/1000
0/I00
(00- 0-60
t0O 6 61
O/20
I/20 1
0/2 00
1 / 10 1
a Fiber Concentration based on the total easter 00 albestus Fibers taunted
b Concentration based upon cur tetal noter of chrysoc lie and amphibole structures counted These asbestos strsctures include asbestos fibers.
asbestos matrices/uebrus. asbestos clsslers/clupes aod asbestos bundles
tess than 10 4 10cm In 00 fields were counted Fiber concentration based on the actual mutter of fibers conrted In 100 Fields fmer Coiucen-
tration is below the reliable limit of guantutatoon (I e • 10 fibers in 100 fields) Saoiplo calculation
10 Fibers/IOU Fields effective cotleclin area of tOe filler (on’ )
Lower limit of reliable qsiantitation - lume pf jlTijnpleo On’ ) A microscooic field area jno’)/field
10 Fibers/tOO fields 055 iw’/filter • 72770 Fibers/r’
I 200 n 1 ° 0 (03136 mn’i’FfeId
he Fibers were detetted in 02 fields Below the detection limit Ce 9 • counting 05 iiber in 100 fields) Sample calculation
0 5 Fiber/lOG fields ( (fectune collecting area of the filler (cn’J
Oetectoon limit • volume of air sampled Jn’) a Niteoncopic Field Irea )on’)/fueld
0 S flber/l00 fields 855 vni 1 /Filier
1 700 n’ i/ffl3 • 1136 f Ibers/c ’
e Selow detecl lee 11011 100 fibern or acructures counted iv 20 grid openings) Sample cilculal ion
I fiber Area of filter (cni’l __________________
06tectlor lien • No of grid urea of grid openiojltW) a oo 1 i of air ( . 0 )
openings scanned
fiber 86cm _____
25 063e10acm’ 1 70 Gm’ • 560 0 iibers/m’
samp 1 e collected hol vet analyzed
O he fibers were detected urn 100 fIelds
No asbeston fibers or structures were detected in 20 grid openings
One asbenoos fiber or structure was delecied in 20 grid epevin 9 s
30
-------
ACM
T(M
NA
A
118
A
.8 00? 0
045 .0 005 0 060
.0 00? 0
045
0 006 0 025
0 004 0
057
0 0) ) 0 022
ACM
T ON
I
NA I *
l)ft I N
ACM TIN
I A AI_ I
I ACM ________
IsA A MA A
O 001 0 002 0 006 0 011
0 002 0 0) 0 0)6 0 04)
.0 002 0 007 0 010 0 024
LJIQlLI
ACM TOM
NAI
U UU( U U ., .1 0 03?
.0 002 0 008
0 005 0 0)
AND I (III
ACM 1CM
.0 002 0) .0 006 (6)
.0 002 0) 0 01 1 (8)
.0 002 8)
.0 007 8)
‘0 0 ? (a)
Figure 10. Results of phase—contrast and transmission-electron microscopy
nonaggressive (NA) and aggressive (1) sampling conditions.
analyses from
Note: All concentrations are fibers/cm 3 . Data are listed by location A through C
(top to bottom).
0 008 0 032 0 0)8 0 041
0006 0048 0 0 )7 0 104
0 01 0 035 0 °‘ _ I _ ! -
A
______ ) “-. - s”-_-
15
B
cLi.
:r E’J
J1S3
SOLES C1 M ..LE
-J
I
L,s A Y
173
\ A
1
I-
LT
B
p.
# 179
\
.0 002 0 044 0 DI I U 008
0 002 0 003
-------
I I I J T ‘ I I I I ‘ I I I I I
•uuuuuuuuiussusu NONASBESTOS AREAS
AGGRESSIVE TEM
u.... NONASBESTOS AREAS
AGGRESSIVE PCM
....,.s. NONASBESTOS AREAS
NONAGGRESSIVE TEM
•uuuuuuuuuu..u.suu..us.uu NONASBESTOS AREAS
NONAGGRESSIVE PCM
ii. . ,. .u..u.u..u.. ABATED AREAS
AGGRESSIVE TEM
•uuui u,uuuuuuusuuuuuuuu .uus ABATED AREAS
AGGRESSIVE PCM
...i....... ABATED AREAS
NONAGGRESSIVE TEM
(A) uuuuuusuuu u.uuu.i ABATED AREAS
NONAGGRESSIVE PCM
uuuiuuuuuuuu AMB I ENT — RANGE
II ,.. ulsit
,•••,• 1 •• 1 • 1 AMBIENT 25 75
PCM PERCENTRES
I I I I I I 111111 I 1 1111111
.001 .002 .003 .004.005 .007 .010 .020 .030 .040.050 .070 .100 .200 .300 .400.500 .700 1.00 2.00
i0 6 FIBERS/rn 3
Figure 11. Comparison of airborne fiber concentration.
-------
TABLE 2 COMPARISON OF NONAGGRESSIVE AND AGGRESSIVE SAMPLING RESULTS
FOR POSTABATEMENT TESTING
Samples
included
in comparison
PCH
Aggres-
siveI
Non-
Aggres-
sive
fibers,a
10 6 /m’
TEN
Aggresslve/
nonaggress ive
Nonaggressive
PCM________ TEM
Ag!
ressive
TEN
No of
samples
Fibers,a
lOb/m3
No. of
samples
Asbesto
fibers,
10 6 /m’
Asbestos
struc-
tureS,d
1O 6 /m
TEM/PCN
fibers
No. of
samples
Flbers,a
1O 6 /m
No. of
samples
Asbestos
fibers.
10 6 /ms
Asbestos
struc-
turesa
10 6 /ms
TEMJPCM
fibers
asbesto
fibers
asbestos
tructures
Abated areas
Nonasbestos areas
Outdoors
9
7
5
0.003
<0.002
<0.002
9
3
2
0.010
0.015
0.006
0.010
0.015
0.006
3.3
7.5
3.0
9
7
0
0.021
0.016
-
9
3
0
0.037
0.030
-
0.040
0.031
-
1.8
1.9
-
7.0
8.0
-
3.7
2.0
-
4.0
2.1
-
aAll concentrations are geometric means.
-------
TABLE 3 COMPARISON OF SAMPLING RESULTS BY SAMPLE LOCATION 8
Samples included
in comparison
Sample location comparisons
Indoor abated!
indoor nonasbestos
Indoor abated!
outdoors
Indoor
nonasbestos/
outdoors
PCM-Nonaggressive
PCM-Aggressive
TEM-Nonaggressive
TEM-Aggressive
3.0
1.3
0.7 ( 0 • 7 )b
1.2 ( 1 • 3 )b
3.0
3.5
1.7 ( 1 • 7 )b
6.2 ( 67 )b
1.0
16.0
2.5 ( 2 • 5 )b
5.0 ( 52 )b
8 All quantities are ratios of the geometric mean fiber concentrations. For
PCM samples, fiber concentrations include all fibers greater than 5 ni in
length; for TEM samples, fiber concentrations include all asbestos fibers.
bRatio of geometric mean concentrations of asbestos structures.
34
-------
TABLE 4. SUMMARY COrIPARISON OF PCM AND TEM ANALYSES OF AIR SAMPLES
COLLECTED DURING NONAGGRESSIVE AND AGGRESSIVE CONDITIONSa
a Al) values ore çeDnetrlc means.
b BDL = Below detection limit (21.136 fibers/in 3 ).
C B BQ Below limit of reliable quantitation (:22.720 fibers/rn 3 ).
d Geometric mean based on two sample values. One sample value was below tbe detection limit for TEH analysis
(5,688 sbestoi fibers or structures/mi).
Analytical technique
Outdoor (ambient)
Nonasbestos areas Abated areas
Nonaggressive
Aggressive
lionaggressive
Aggressive
Phase contrast microscopy (PCM),
fibers ( 5 urn)fr
BOl
801
BLRQC
BLRQ
BLRQ
(16.000)
(3,000)
(21.000)
Transmission
electron microscopy
(1(M)
asbestos
fibers/mi
6 , 000 d
15,000
30.000
10,000
37,000
asbestos
structures/rn 3
€OOO
15,000
31,000
10,000
40.000
-------
The difference between PCM and TEN results from indoor sampling of nonasbes-
tos areas was also statistically significant (p c 0.10) under nonaggressive
sampling conditions; however, this conclusion was based on a small sample
size (n = 3). The ratios of TEM/PCM concentrations for nonaggressive sam-
pling were 3.0 for ambient samples, 3.3 for indoor abated-area samples, and
7.5 for indoor nonasbestos-area samples. The difference between PCM and TEM
results is not statistically significant (i.e., p > 0.05) for iidoor samples
from both abated and nonasbestos areas under aggressive sampling conditions.
For aggressive sampling in abated areas, the ratio of TEM/PCM was 1.8. For
aggressive sampling in nonasbestos areas, the ratio of TEM/PCM was 1.9.
Sampling Conditions
Table 2 also provides a comparison of nonaggressive and aggressive
sampling conditions for PCM and TEN analyses in both abated and nonasbestos
areas. The difference between the geometric average fiber concentrations
under nonaggressive and aggressive sampling conditions was statistically
significant (i.e.. p c 0.002) for both PCM and TEN in abated areas. For PCM
analyses, the ratio of aggressive to nonaggressive fiber concentrations was
7.0; for TEN analyses, the ratio was 3.7. For sampling conducted in nonas-
bestos areas, the difference between the geometric average fiber concentra-
tions under nonaggressive and aggressive sampling conditions was statis-
tically significant for PCM analyses (i.e., p < 0.002), but not statistically
significant for TEN analyses (i.e., p 0+4). For nonasbestos areas, the
ratio of aggressive to nonaggressive fiber concentrations for PCM analyses
was 8.0; for TEN analyses, the ratio was 2.0.
Appendix 0 presents a comparison of TEN results from two air samples
taken from the same location during nonaggressive and aggressive conditions.
These figures exemplify the findings of this study, i.e., that the concentra-
tions of asbestos fibers and structures measured under aggressive sampling
conditions are higher than those measured under nonaggressive conditions.
Comparison of Indoor Abated Samples and Ambient Saniples
Also included in Tables 2, 3, and 4 are the PCM and TEM analyses of
samples collected in the ambient atmosphere for comparison with samples
collected in indoor abated areas. For samples analyzed by PCM, the geometric
mean fiber concentration was 0.003 x 106 fibersfm 3 for indoor samples (non-
aggressive) in abated areas compared with less than 0.002 x io fibers/m 3 for
ambient samples. The PCM method, however, is not sufficiently sensitive for
reliable detection of these ambient and indoor (nonaggressive) concentra-
tions. All ambient concentrations were below the detection limit of the PO’I
method and concentrations in indoor abated areas were below the lower limit
of reliable quantitation by this method. Consequently, the observed differ-
ences between the two sample groups are probably not meaningful.
For the TEN samples collected inside abated areas (under nonaggressive
conditions), the geometric mean asbestos fiber concentration was 0.010 x 106
fibers/n 3 compared with 0.006 x 106 fibers/rn 3 for ambient samples--a ratio of
36
-------
1.7. The observed difference between these indoor, nonaggressive, TEM asbes-
tos fiber concentrations and the ambient TEM asbestos fiber concentrations
was not statistically significant (p > 0.15). The difference between asbes-
tos fiber concentrations under aggressive sampling conditions in indoor
abated areas and ambient asbestos concentrations was statistically signifi-
cant (p < 0.02). The ratio of asbestos fiber concentrations by TEM under
aggressive sampling in indoor abated areas to ambient TEN fiber concentra-
tions was 6.2.
Comparison of Indoor Nonasbestos Samples and Ambient Samples
For samples analyzed by PCM, the geometric mean fiber concentration for
indoor samples collected nonaggressively in nonasbestos areas was below the
detection limit of the analytical method, as were the ambient PCM samples.
Consequently, no meaningful comparisons can be made. For PCM samples col-
lected aggressively, the geometric mean fiber concentration was 0.016 x 106
fibers/rn 3 compared with less than 0.002 x 106 fibers/m 3 for ambient samples,
a ratio of 16.0 (if a concentration of 0.001 x 106 fibers/rn 3 for ambient
samples is assumed). The observed difference between aggressive (nonasbestos
area) PCM fiber concentrations and the ambient PCM fiber concentrations was
statistically significant (p < 0.01). One nonasbestos area (Room 152, In-
strumentation Laboratory) was extremely dusty. The aggressive sampling
procedure entrained large quantities of “house dust” that had accumulated on
shelf and cabinet tops over many years. This accounted for the relatively
high PCM fiber counts.
For TEM samples collected inside nonasbestos areas (under nonaggressive
conditions), the geometric mean asbestos fiber concentration was 0.015 x 106
fibers/rn 3 compared with 0.006 x 106 fibers/rn 3 for TEM ambient samples, a
ratio of 2.5. The observed difference between these nonaggressive, indoor
(nonasbestos area) TEM asbestos fiber concentrations and the ambient TEM
asbestos fiber concentrations was not statistically significant (i.e.,
p > 0.10). The difference between TEM asbestos fiber concentrations under
aggressive sampling conditions in indoor nonasbestos areas and ambient TEM
asbestos concentrations was not statistically significant (i.e., p > 0.10).
The ratio of asbestos fiber concentrations determined by TEM under aggressive
sampling conditions inside nonasbestos areas to ambient TEM fiber concentra-
tions was 5.0. Because the comparisons between fiber concentrations for TEM
samples in nonasbestos areas (aggressive or nonaggressive) and ambient sam-
ples are based upon very small sample sizes (n = 3 and n = 2, respectively),
the observed differences in fiber concentrations between these two sampled
locations cannot be found statistically significant at a probability level of
< 0.05.
Comparison of Samples From Indoor Abated and Indoor Nonasbestos Areas
For all PCM samples (aggressive and nonaggressive), the observed differ-
ence between fiber concentations in indoor abated areas and indoor nonasbes-
tos areas was not statistically significant (p > 0.08 for nonaggressive
conditions; p > 0.05 for aggressive conditions). For PCM samples collected
under nonaggressive conditions, the ratio of fiber concentrations in abated
37
-------
areas to nonasbestos areas was 3.0 (a concentration of 0.001 x 106 fibers/rn 3
for indoor nonasbestos samples was assumed since the mean geometric concen-
tration in indoor abated areas was less than 0.002 x iO fibers/rn 3 ). For PCM
samples collected under aggressive conditions, the ratio of fiber concentra-
tions in abated areas to nonasbestos areas was 1.3.
For all samples analyzed by TEM, the difference between abated and
nonasbestos areas was also not statistically significant (p > 0.10 for nonag—
gressive conditions; p > 0.10 for nonagres sive conditions). For TEM samples
collected under nonaggressive conditions, the ratio of asbestos fiber concen-
trations in abated areas to nonasbestos areas was 0.7. For TEM samples
collected under aggressive conditions, this ratio was 1.2 (1.3 for asbestos
structures).
Expanded TEM Data From Nonaggressive and Aggressive Sampling Conditions
Table 5 presents additional data from the TEll asbestos analysis reports,
including the types of asbestos fibers observed, the number of other fibrous
structures, and the number of nonfibrous asbestos particles (i.e , matrix/de-
bris, cluster/clumps, and bundles). The relationship and significance of
these other parameters, as influenced by different sampling conditions and
monitoring locations, were not evaluated as part of this study.
38
-------
TABLE 5. EXPANDED TEM DATA FROM NONAGGRESSIVE AND AGGRESSIVE SAMPLING CONDITIONS
Sampling location
Sample
number
1O
Asbestos,
fibers/rn 3
Nonaggressive
Concentration, io units/rn’
Tot
10 b asbestos
Tot
asb
Chry
Amp
Tot
fib
struc-
Chry
struc-
Amp
struc-
Other
struc-
Asb
mat!
Asb
clus/
Asb
bun-
structures/rn 3
fib
rib
fib
fib
tures
tures
tures
tures
deb
clump
dies
w
‘ .0
Abated areas
Room 155
A 2 0.006 0.006
9 3 002 0.015
C 1 001 0.01
Room 151
A 4 003 003
B 5 002 0.016
C 6 0.01 0.01
Room 159
A 8 ND ND
B 7 0006 0006
C 9 001 0.01
Nonasbestos areas
Room 173
A 13 0.01 001
B 14 Sample not analyzed
kooin 152
A 10 0.01 I 0.01
B 16 Sample not analyzed
Room 205 I
A 11 Sample not analyzed
B 19 002 I 0.02
C 17 Sample not analyzed
Outdoors (ambient)
Ground 21 ND ND
22 Sample not analyzed
44 Sample not analyzed
45 Sample not analyzed
Roof 18 Sample not analyzed
20 Sample not analyzed
42 Sample not analyzed
33 Sample not analyzed
43 001 001
Sample blanks 60 ND ND
61 ND ND
a NO None detected in the grid openings examined.
h One nonasbestos fibrous structure was detected.
O 006
0 02
0.01
0.03
O 02
O 01
ND
0 006
0.01
0.01
0.01
O 02
ND
0.01
ND
ND
O 005
ND
0.01
0.01
ND
ND
0.006
ND
ND
ND
ND
ND
ND
ND
ND
0.006
0.01
0.01
0.02
0.006
0.01
ND
ND
0.01
0.01
0.01
0.02
ND
O 01
ND
ND
0 01
0.02
0.03
0.03
0.02
0.01
ND
O 006
0.03
0 03
0.02
0.03
ND
0 01
ND
ND
0 01
0.03
0.03
0.03
0.02
0.01
ND
0.006
0.03
0.03
0.02
0.03
O 03
0.01
ND
ND
0.005
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0 005
lID
0.01
0.01
lID
ND
0.006
ND
ND
ND
ND
ND
ND
ND
ND
0.006
0 01
0 01
0.02
0 006
0.01
ND
ND
0.01
0.01
0.01
0.02
ND
0 01
ND
ND
ND
1.005
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
O 006
0 01
0.02
0.006
0.006
NO
ND
ND
0.02
0 02
0.006
0.006
O 03
ND
b
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND ND
ND ND
ND ND
(conti nued)
-------
TABLE 5 (continued)
Aggressive
Concentration, 106 units/in 3
Tot
Samphng location
Sample
number
Asbestos, 106 asbestos
jQb fibers/rn 3 structures/n 3
Tot
asb
fib
Chry
fib
Amp
fib
Tot
fib
fib
struc-
tures
Cliry
struc-
tures
Amp
struc-
tures
Other
struc-
tures
Asb
mat!
deb
Asb
clus/
clump
Asb
bun-
dIes
27
25
26
28
29
30
31
46
34
35
36
37
38
39
40
41
bated areas
Room 155
A
B
C
Room 157
A
B
C
Room 159
A
B
C
Nonasbestos areas
Room 173
- A
CD B
Room 152
A
B
Room 205
A
B
C
Outdoors (ambient)
Ground
Roof
o 02 0.026
0.04 0.04
0.02 0.02
0.04 004
0.10 0.106
0.06 0.06
0.06 0.07
0 03 0.03
0 02 0.03
0 006 0.006
Sample not analyzed
0.01 I 0.01
Sample not analyzed
Sample not analyzed
0.03 i 0.03
Sample not analyzed
0 02
O 04
0.02
0.04
11.10
0.06
0.06
0 03
0.02
0.006
0.01
0.03
0.006
0.02
‘ I D
0.01
0.006
N I l
‘ ID
‘ ID
ND
ND
ND
ND
0.01
0.02
0.02
0.03
0.10
0.06
0.06
0.03
0.02
0.006
0.01
0.03
0.04
0.05
0.03
0.05
0.16
0.08
0.07
0 06
0.05
0.02
0.02
0 06
0.006
0 02
NO
0.01
0 006
ND
ND
ND
ND
ND
ND
HO
0.02
0.02
0.02
0.03
0.10
0.06
0.07
0.03
0.03
0.006
0.01
0.03
ND
0.006
NO
ND
ND
0.006
NO
ND
0.006
ND
0.01
NO
ND
ND
ND
ND
ND
ND
0.006
ND
ND
ND
NO
ND
0.006
ND
l ID
NO
ND
ND
ND
ND
ND
ND
lID
ND
0.05
0.06
0.03
0.06
016
0.08
0.08
0.06
0.06
0.02
0 02
0.06
0.03
0 02
0.006
0.01
0.05
0.02
0,01
0.03
0.03
0.01
0.01
0.03
Sample blanks
-------
REFERENCES
1. U.S. Environmental Protection Agency. Asbestos—Containing Materials in
School Buildings: A Guidance Document, Part 1. Office of Toxic Sub-
stances, Washington, D.C. 1979.
2. Sawyer, R. N., and D. M. Spooner. Asbestos—Containing Materials
School Buildings: A Guidance Document, Part 2. Office of Toxic
stances, U.S. Environmental Protection Agency, Washington, D.C.
3. U.S. Environmental Protection Agency. Guidance for Controlling Friable
Asbestos-Containing Materials in Buildings. Office of Toxic Substances,
Washington, D.C. 1983.
Agency. Guidance for Controlling
in Buildings. Office of Toxic Substances,
0. Environmental Release of Asbestos From Coninercial Product
Engineering-Science, Fairfax, Virginia. 1984.
Institute for Occupational Safety and Health. Asbestos Fibers
NIOSH Method No. P&CAM 239. NIOSH Manual of Analytical
Second Ed., Vol. 1. U.S. Departirient of Health, Education, and
Cincinnati, Ohio. April 1977.
8. Yamate, G., S. C. Agarwal, and R. 0. Gibbons. Methodolo9y for the
Measurement of Airborne Asbestos by Electron Microscopy (Draft). Pre-
pared by ITT Research Institute for the Office of Research and Develop-
ment, U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina. July 1984.
9. Mosteller, F., and R. E. K. Rourke. Sturdy Statistics: Nonparametrics
and Order Statistics. Addison Wesley, Reading, MA. 1973. pp. 56—72
and Table A—9, pp. 337—338.
in
Sub-
1979.
4. U.S. Environmental Protection
Asbestos-Containing Materials
Washington, D.C. 1985.
5. Falgout,
Shaping.
6. Chatfield, E. J.
blent Atmospheres.
7. National
in Air.
Methods,
Welfare,
Measurement of Asbestos Fibre Concentrations
Study No. 10, Ontario Research Foundation.
in Am-
1983.
41
-------
APPENDIX A
METHODOLOGY FOR THE MEASUREMENT OF AIRBORNE ASBESTOS
BY TRANSMISSION ELECTRON MICROSCOPY — LEVEL Ii
ANALYSiS PROTOCOL*
LEVEL II ANAIYS1S*
SUMMARY OP PROTOCOL
Level II analysis is a regulatory technique consisting of Level I
analysis plus chemical elemental analysis. Morphology, size, SAED pattern,
and chemical analysis are obtained sequentially. By a process of elimination,
mineral fibers are identified as chrysotile, amphibole, ambiguous, or “no—
identity by morphology and SAED pattern. X—ray elemental analysis is used to
categorize the amphibole fibers, identify the ambiguous fibers, and confirm or
validate chrysotile fibers.
Level II analysis is summarized as follows:
(1) A known volume of air is passed through a polycarbonate
membrane filter (pore dIameter, 0.4 tim; filter diameter,
37 or 47 mm) to obtain approximately 5 to 10 g of
particulates per cm 2 of filter surface.
(2) The particulate—laden filter is transported in its own
filter holder.
(3) The filter is carbon—coated in the holder.
(4) The particulates are transferred to an EM grid using a
refined Jaffe wick washer.
(5) The EM grid, containing the particulates, is gold—coated
lightly.
(6) The EM grid is examined under low magnification (250X to
1000X) followed by high—magnification (16,OflOX on the
fluorescent screen) search and analysis.
(7) A known area (measured grid opening) Is scanned, and the
asbestos structures (fibers, bundles, clusters, and
matrices) are counted, sized, and identified as to
asbestos type (chrysotile, amphibole, ambiguous, or no
identity) by morphology and by observing the SAEI) pattern;
and finally by elemental analysis using EDS.
(8) The observations are recorded——a minimum of 100 fibrous
structures or 10 grid openings, whichever Is first.
(9) The data are reduced and the results reported.
*
Reprinted from Yamate, G., S. C. Agarwal, and R. 0. Gibbons. 1984.
Methodology for the Measurement of Airborne Asbestos by Electron
Microscopy. Draft Report. Office of Research and Development, U.S.
Environmental Protection Agency, Washington, D.C. Contract No.
68-02-3266.
42
-------
EQUIPMENT, FACILITIES, AND SUPPLIES
The following items are required for Level I analysis:
1) A modern 100—ky ltM equipped with an EDS. A scanning
accessory as found in a STEM will increase the versatility
and analytical capability for very small fibers and for
fibers adjacent to other particulate matter. The
microscope should be equipped with the fluorescent viewing
screen inscribed with graduation of known radii to
estimate the length and width of fibrous particulates.
(2) A vacuum evaporator with a turntable for rotating
specimens during coating, for such uses as carbon—coating
polycarbonate filters, gold—coating EM grids, and
preparing carbon—coated EM grids.
(3) An EM preparation room adjacent to the room housing the
EM. This room should either be a clean—room facility, or
contain a laminar—flow class—lOt ) clean bench to minimize
contamination duing EN grid preparation. Pifler handling
and transfer to E li grids should he performed in a clean
atmosphere. Laboratory blanks should be prepared and
analyzed weekly to ensure quality of work.
(4) Several refined Jaffe wick washers for dissolving membrane
filters.
(5) Miscellaneous EM supplies and chemicals, including carbon—
coated 200—mesh copper grids, grid boxes, and chloroform.
(6) Sample collection equipment, including 37—mm—diameter or
47—mm—diameter filter holders, 0.4—pm (pore size)
polycarbonate filters, 5.0—pm (pore size) cellulose ester
membrane filters for back—up, a sampling pump with
ancillary equipment, a tripod, critical orifices or flow
meters, and a rain/wind shield.
DESCRIPTION OF METHODOLOGY
I. Type of Samples —Source
This protocol is an expansion of the method originally developed for the
EPA for measuring airborne asbestos (Samudra et a l., i 77; Samudra et at.,
1978). A broad interpretation of airborne has been to apply the term to
aamples obtained from ambient air (the original purpose), aerosolized source
materials (such as the asbestos workplace environment, and fugitive dust
emissions), bulk—air material (such as total suspended particulate (TSP)
samples, dust, and powders) and any other type of sample obtained by nonre-
strictive use of (1) collection of a volume of air, (2) separation fron the
air, and (3) concentration of the particulates onto a substrate. The airborne
protocol has also been applied to samples collected in the regulatory areas of
the EPA, as compared with, for example, the workplace environment (National
43
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Institute of Occupational Safety and Health), mining activities (U.S. Bureau
of Mines), and shipboard atmosphere (Federal Maritime Administration).
The present methodology has been optimized for applicatimn specifically
to samples collccted from a volume of air in which the asbestos concentration
is considered a minor component of the total particulate loading (other analy-
tical methods are available for samples known to contain high concentrations
of asbestos); and in which the particles are less than 15 im in diameter,
since particles greater than 15 vm either are not inhaled or are deposited in
the upper respiratory tract and expelled, and preferably less than 10 urn in
dianet r as recommended by the Clean Air Scientific Advisory Committee
(Hileman, 1981), since particles up to 10 urn can be absorbed by the alveolar
region of the lung. These concentration and size restrictions will preclude
many air samples collected in an asbestos—processing environment and in bulk-
air material from t e complete methodology. However, such Bamples can still
be examined with the TEN, within the limitations of the instrument by changes
in preparation techniques——provided the effects on the final results, such as
fractionation of size and representativeness of the sample, are carefully
considered.
2. Sample Collection and Transport
Sample Collection—
Sampling procedures vary depending on the nature of the sample, purpose
of collection, analytical method to be used, sample substrate, and time and
cost of sample collection relative to the total analytical effort. Neverthe-
less, the primary objective of sample collection always is to obtain a
representative, unbiased sample.
Impingers, Impaction devices, electrostatic precipitators, and thermal
precipitators have been used in sample collection, but each has limitations.
Presently, the preferred substrates are membrane filters, which are manufac-
tured from different polymeric materials, including polycarbonate, mixed
esters of cellulose, polystyrene, cellulose acetate, and cellulose nitrate.
Polycarbortate membrane filters differ from the others in being thin, strong,
and smooth—surfaced, and in having sieve—like construction (circular pores
from top surface to the bottom). The other membrane filters are thicker, have
irregular—surfaces, and have depth—filter construction (tortuous paths from
top surface to bottom).
Consequently, polycarbonate filters have been selected for airborne
asbestos analysis. The collection of small—sired particles (prefer less than
10 ,m in diameter), the light loading of particulates, the uniform distribu-
tion of particulates attainable using a depth—type backing filter, the smooth
surface and circular holes (which aid in determining size and instrument tilt
axis), and the relative ease in grid transfer (thin and strong) minimize
disadvantages of lack of retention and/or movement of large particles during
handling. Other membrane materials, such as the cellulose ester type, are
recommended for phase contrast and PLM, heavy particle loadings, and physical
retention of large particles.
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In microscopical analysis, uniformity of particulate distribution and
loading is critical to success. Air samples are taken on 37—mm—diameter or
47—mm—diameter, 0.4—pm (pore size) polycarbonate membrane filters using the
shiny, smooth side as the particle—capture surface. Cellulose ester—type
membrane filters (pore Si:!, 5.0 pin) are used to support the polycarbonate
filter on the support pad (37—mm—diameter personal sampler) or bn the support
plate (47—mm—diameter holder).
Field monitoring cassettes (37—mm—diameter) of three—piece construction
are available from several manufacturers. As with the 47—mm—diameter filters,
loading the cassettes with the support pad, back—up filter, and 0.4 u 7 ’ (pore
size) polycarbortate filter should be carefully performed on a class—br) clean
bench. Since the filters are held in place by pressure fit rather than b .
screw tightening, air must not enter from the sides of the unit; a plastic
band or tape (which can double as a label) should be used as a final seal.
Collecting airborne samples with proper loading requires experience.
Each of the following techniques is useful in collecting airborne samples for
direct microscopy, preserving representative sizes, without diluting
particulate deposits:
(1) For long—term sampling at a site, test samples should be
returned to the laboratory by express mail service, or air
express service or by being hand—carried, and should then
be analyzed by scanning electron microscopy.
(2) The estimated particulate loading (deposit is barely
visible to the naked eye) should be bracketed by varying
the filtration rate .and using the same time, or by varying
the time and using the same filtration rate.
(3) An automatic particle counter, such as a light—scattering
instrument (0.3—pm detection) or a real—time mass monitor
(0.1—pm detection), should he used to obtain an
approximate particulate—loading level of the area.
Although any one of the three techniques will work, the suggested
technique is to take the samples as a set, varying the sampling rates and
using the same time so as to obtain filter samples with different particulate
loadings. Each set is composed of a minimum of four 37—mm—diameter or 47—mm—
diameter filter units——three for different particulate loadings (low, medium,
high), and the fourth for a field blank. Suggested sampling rates are 0 for
the field blank, 2.48 1/mm for the low loading, 7.45 1/rn for the medium, and
17.62 1/mm for the high, for a 30 mm sampling period using a 47—mm—diameter
filter holder. Simultaneous sampling will provide at least one sample with a
particulate loading suitable for direct EM analysis.
TSP’s range from 10 pg/rn 3 in remote, nonurban areas, to 60 pg/m 3 in near—
urban areas, to 220 pg/rn 3 in urban areas. However, for heavily polluted
areas, TSP levels may reach 2000 pg/rn 3 . A loading of 5 to 10 pg per cm 2 of
filter is adequate for EM analysis; values beyond 20 to 25 ug per cm 2 reouire
a dilutirtn treatment. As an example, for 47—mm—diameter filters at face
velocities of 3.0 cm/s (2.48 1/mm), Q.0 cm/s (7.45 1/mm), and 21.2 cm/s
45
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(17.62 1/mm), respectively, air volumes of 74.4 1, 223.5 1, and 528.6 1 are
sampled in 30 mm. For a TSP level of 200 g/m 3 , 14.88 ,sg (1.07 isg/cm 2 ),
44.7 pg (3.23 pg/cm 2 ), and 105.7 pg (7.63 pg/cm 2 ), respectively, would be
collected on 47—mm-diameter filters (which would have effective filtration
areas of 13.85 cm 2 ). The sampling time could be increased to 60 mm for areas
having lower TSP levels, or reduced L a heavily polluted area (source
emissions).
Airborne samples from emission sources contain coarse particles (above
the respirable size) of large matrix structures, binder materials, road dust,
clay minerals, fillers, and other materials. For these samples, a fifth
filter unit can be added that has a size—selective inlet (cyclone, impactor,
or elutriator) attached prior to the filter unit. The flow pattern and flow
rates of the tandem sampling arrangement must be checked before use. A
satisfactory, tested combination presently used in California is a cyclone—
filter unit with a D rj cut—off of 2.5 pm at 21.7 1/mm, and a DSO cut—off of
3.5 urn at 15.4 1/mm (John and Reischl, 1980). Additional sampling devices,
such as impingers (used in biological sampling), impactors , and other
designated filter units (for TSP, XRD, or x—ray fluorescence (xRF), for
example) can be added to the system to obtain supplementary as well as inter-
related data.
This expandable multifilter sampling unit, designated Hydra, offers the
following advantages:
(1) It is small, inexpensive, and compact, so that an adult
can easily handle it.
(2) It is efficiently designed, and includes a tripod,
sampling pump, manifold, critical orifices, and a row of
preloaded 37—mm—diameter or 47—mm—diameter filter
holders. A rain/wind shield, size—selective cyclone—
filter units, tubing, and other extras can he added as
needed.
(3) Its sample preparation steps and handling are minimized.
(4) It allows complementary as well as supplementary analysis
(TSP, size fractionation, bacteria, and XRF, for example),
although additional air sampling capacity Is required.
(5) It accommodates ambient air and source emission samples,
with or without a size—selective inlet.
(6) It allows synchronous sampling in several places in the
vicinity following the same sampling procedure, thereby
accommodating particulate concentration fluctuations.
(7) It includes filter holders that serve as transport and
storage units.
Hydra’s disadvantages are a short sampling period, which may catch an episode;
a small sampling quantity or volume, which may not indicate the presence of
asbestos fibers; and a detection limit of 2 x lOll fibers/rn 3 for sampling 1 m 3
of air with the 47—mm—diameter filter.
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using 8 inch x 10 inch, or 102—mm—diameter filter sizes, is not
recommended. The sampling units are designed for purposes other than
microscopy. Interchanging the type of sample substrate filter (glass fiber or
paper to polycarbonate) does not correct the inherent problems of filter size
and sampling unit.
Sample Storage and Transport—
Once the sample is acquired, its integrity must be assured, and
contamination and loss of fibers prevented, until it is examined under the
EM. The low cost and small size of the 37—nm—diameter and 47—mm—diameter
filter holders enables them to be used as combination storage and transport
containers. The filter holders should be maintained in a horizontal position
during storage and transport to the laboratory so that the particulate—loaded
filters can be removed under optimally controlled conditions in the
laboratory.
For 47—mm—diameter holders (open—face) to be used in transport or
storage, the screw cap is carefully removed, and the shiny, waxy, stiff
separator paper used to keep the polycarbonate filters apart is carefully
placed on the retaining ring. The cap is then carefully screwed back on so
that the separator paper seals and protects the particulate—loaded filter
without touching it. The 37—mm—diameter, three—piece filter holder (aerosol
monitor) is used in its open—face position, and capped after usage for
transport and storage.
When the more expensive 47—mm—diameter holder is to be re—used
immediately, the particulate—loaded filter should be carefully removed and
placed in a 47—mm—diameter Petri—slide (such as that manufactured by the
tlillipore Corp.*) This transfer takes place in the field rather than in the
laboratory, so that the Petri—slide should be taken into the field. The 37—
mm—diameter filter holder or the 47—mm—diameter holder/petri—slide should be
secured and all necessary sample identification marks and symbols applied to
the holder.
3. Sample Preparation for Analysis—Grid Transfer
Carbon—Coating the Filter—
The polycarbonate filter, with the sample deposit and suitable blanks,
should be coated with carbon as soon as possible after sampling is
completed. To begin this procedure, the particulate—loaded 47—mm—diameter
polycarbonate filter is removed from the holder and transferred carefully to
an open—faced 47—mm—diameter Petri—slide for carbon—coating in the vacuum
evaporator (see Figure Al, Appendix A). If the 47—mm—diameter filter is
already in the Petri—slide, the cover is replaced with an open—face cover,
minimizing filter disruption. The 37—mn—diameter filter is left in the
holder, but the upper lid is removed to create an open—faced filter. The
open—faced holders are placed on the rotating turntable in the vacuum
* Millipore Corp., 80—T Ashby Rd., Bedford, Mass. 0173fl
47
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evaporator for carbon—coating. Pigure A2 shows the multiple—coating
arrangement in the evaporator; Figure A3 shows a close—up of the 37—mm—
diameter and the modified 47—mm—diameter holders for carbon—coating.
For archival filters and those of larger sizes, portions of about 2.5 cm
x 2.5 cm should be cut midway between the center and edge t.jinga scalpel.
The portions are then attached with cellophane tape to a clean glass
microscope slide and placed on the turntable in the vacuum evaporator for
coating.
Any high—vacuum carbon evaporator may be used to carbon—coat the filters
(CAUTION: carbon sputtering devices should not be used). Typically, the
electrodes are adjusted to a height of if) cm above the level of the filters.
A spectrographically pure carbon electrode sharpened to a neck of 0.1 cm x
0.5 cm is used as the evaporating electrode. The sharpened electrode is
placed in its spring—loaded holder so that the neck rests against the flat
surface of a second carbon electrode.
The manufacturer’s instructions should be followed to obtain a vacuum of
about 1.33 x IO Pa (1 i0 torr) in the bell jar of the evaporator. With
the turntable in motion, the neck of the carbon electrode is evaporated by
increasing the electrode current to about 15 A in 10 s, followed by 20 to 25 A
for 25 to 30 s. If the turntable is not used during carbon evaporation, the
particulate matter may not be coated from all sides, resulting in an undesir-
able shadowing effect. The evaporation should proceed in a series of short
bursts until the neck of the electrode is consumed. Continuous prolonged
evaporation should be avoided, since overheating and consequent degradation of
the polycarbonate filter may occur, impeding the subsequent step of dissolving
the filter. The evaporation process may be observed by viewing the arc
through welders goggles (CAUTION: never look at the arc without appropriate
eye protection). Preliminary calculations show that a carbon neck of 5 mm 3
volume, when evaporated over a spherical surface 10 cm in radius, will yield a
carbon layer that is 40 nm thick.
Following carbon—coating, the vacuum chamber is slowly returned to
ambient pressure, and the filters are removed and placed in their respective
holders or in clean, marked Petri dishes for storage on a clean bench.
Transfer of the Sample to the D1 Grid—
Transferring the collected particulates from the carbon—coated
polycarbonate filter to an EM grid is accomplished in a clean room or on a
class—100 clean bench. The transfer is made in a Jaffe wick washer, which is
usually a glass Petri dish containing a substrate to support the EM
grid/carbon—coated membrane filter combination. Solvent is added to a level
to just wet the combination and cause gentle dissolution of the membrane with
minimum loss or dislocation of the particulates, resulting in a membrane—free
EM grid with particles embedded in the carbon film coating. The substrate
support can be stainless steel mesh bridges, filter papers, urethane foams, or
combinations of these.
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The refined Jaffe wick washer is described as follows:
(I) The glass Petit dish (diameter, 10 cm; height, 1.5 cm) is
made airtight by grinding the top edge of the bottom dish
with the bottom of the cover dish, with water and
carborundum* powder (80 mesh); this creates a ground—
glass seal (closer fit) and minimizes the need to refill
the Petri dish with added solvent. (The usual glaos
Petri dish was found not to retain the solvent for long
periods of time, and unless the wicking substrate is kept
continuously wet, poor solubiiity of the membrane filter
results, leading to a poor—quality EM grid).
(2) A combination of foam and a single sheet of 9—cm filter
paper is used as the substrate support. A 3—cm x 3—cm x
0.6—cm piece of polyurethane foam (the packing in
Polaroid film boxes) is cut and placed in the bottom
dish. A 0.5—inch V—shaped notch is cut into the filter
paper; the notch is oriented in line with the side of the
foam, creating a well for adding solvent.
Spectrographic—grade chloroform (solvent) is poured into
the Petri dish through the notch until it is level with
the top of the foam
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(6) Once all specimens are placed in the washer, more solvent
is carefully added through the notch to maintain the
liquid level so that it just touches the top of the paper
filter. Raising the solvent level any higher may float
the EM grid off the mesh or displace the polycarbonate
filter section.
(7) The cover is placed in the washer and oriented in place
over the specimen, and a map of the filter/grid/screen
arrangement is made on the glass cover and in the
logbook.
(8) Solvent (chloroform) is added periodically to maintain
the level within the washer until the filter is
completely dissolved by the wicking action (24 to 48 h).
(9) The temperature in the room must remain relatively
constant to minimize condensation of solvent on the
bottom of the cover and subsequent falling of solvent
drops on the EM grid. Should day—night or other
temperature differentials occur, solvent condensation on
the under—surface of the cover can be minimized by
placing the Jaffe washer at a slight tilt (three glass
slides under one edge of the Petri dish parallel to the
row of grids) to allow the condensation drops to flow
toward the lower edge rather than fall on the EM grids.
At temperatures lower than 20°C (68° !), the complete
filter solution may take longer than 72 h.
(10) After the polymer s completely dissolved, the stainless
steel mesh screen with the EM grid is picked up while wet
and set on lens paper tacked to the bottom of a separate
Petri dish. The EM grid is then lifted from and placed
next to the screen to dry. When all traces of solvent
have evaporated, the grid is stored in a grid box and
identified by location and grid box in the logbook.
Figure A4 illustrates the Jaffe wick washer method; Figure AS shows the
vasher. The foam/filter combination is presently preferred, as is use of a
closely fitted (by means of the ground—glass seal) Petri dish.
Gold Coating—
An additional step will aid in subjectively evaluating the SAED pattern.
This step is required for specimens from the upper Great Lakes area and for
those of unknown origins. After the particulates on the filter are
transferred to the EM grid, the grid is held to a glass slide with double—
stick tape for gold—coating in the vacuum evaporator. Several EM grids may be
taped to the glass slide with double—stick tape for gold—coating in the vacuum
evaporator. For comparison, one—half of the EM grids may be cnated and the
other one—half not coated; recognition of the gold—coating is helpful in
searching and x—ray analysis. Several EM grids may be taped to the glass
slide for coating at one time. Approximately 10 cv of 0.015—cm—diameter
50
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(0.006—inch) pure gold wire is placed in a tungsten basket (10 cm from the
rotating table holding the EM grids) and evaporated onto the grid.
The thin gold—coating establishes an internal standard for SAED analysis.
For some mineral species, an internal standard will clarify visual identifica-
tion of the pattern of a fibrous particulate as being or not being an
amphibole species (for example, Minnesotalte as opposed to A nos!te). With
experience, differentiation in SAED patterns CAfl be observed. For samples of
known geographic origins, gold—coating is optional, since the additional
coating hinders observation and identification of small—diameter chrysotile
fibers.
4. TE!I Examination and Data Collection
Figure AlO shows a modern TEM with capabilities for elemental analysis
with an EDS. The grid is observed in the TEM at magnifications of 250X and
I000X to determine its suitability for detailed study at higher magnifica-
tion. The grid is rejected and a new grid used if: (1) the carbon film over
a majority of the grid openings is damaged and not intact; (2) the specimen is
dark due to incomplete dissolution of the polycarbonate filter; or (3) the
particulate loading is too light (unless a blank) or too heavy with particle—
particle interactions or overlaps.
TEN Analysis (Morphology SAED, and X—Ray Analysis)—
The following guidelines are observed for consistency in the analytical
protocol:
(1) Magnification at the fluorescent screen is determined by
calibration with a diffraction—grating replica in the
specimen holder.
(2) A field of view or gate is defined. On some
microscopes, the central rectangular portion of the
fluorescent screen, which is lifted for photographic
purposes, is convenient to use. On others, a scribed
circle or the entire circular screen may be used as the
field of view. The area of the field of view must be
accurately measurable.
(3) The grid opening is selected on a random basis.
(4) The analysis, morphology, and SAED are performed at a
tilt angle of 00.
(5) The recommended instrument settings are: accelerating
voltage, 100 kV; beam current, 100 ijA; film magnifi-
cation, 20,000X (which is equivalent to 16,000x on the
fluorescent screen for this instrument); and concentric
circles of radii 1, 2, 3, and 4 cm on the flunrescent
screen.
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(6) The grid opening is measured at low magnification (about
1000X).
(7) Since asbestos fibers are found isolate 1 as well as with
each other or with other particles in varying arrange-
ments, the fibrous particulaces are characterized as
asbestos structures:
Fiber (F) is a particle with an aspect ratio of 3:1 or
greater with substantially parallel sides.
Bundle (B) is a particulate composed of fibers in a
parallel arrangement, with each fiber closer than the
diameter of one fiber.
Cluster (ci) is a particulate with fibers in a random
arrangement such that all fibers are intermixed and no
single fiber is isolated from the group.
Matrix is a fiber or fibers with one end free and the
other end embedded or hidden by a particulate.
Combinations of structures, such as matrix and cluster,
matrix and bundle, or bundle and cluster, are categorized
by the dominant fiber quality——cluster, bundle, and
matrix.
(8) Counting rules for single fibers, which are illustrated
in Figure A7 are as follows:
(a) Particulates meeting the definition of fiber are
isolated by themselves. % Jith this definition, edge
view of flakes, fragments from cleavage planes, and
scrolls, for example, may be counted as fibers.
(b) Count as single entities if separation is equal to
or greater than the diameter of a single fiber.
(c) Count as single entities if three ends can be seen.
(d) Count as single entities if four ends can be seen.
Ce) in general, fibers that touch or cross are counted
separately.
(f) Two or more fibers are counted as a bundle if the
distances between fibers are less than the diameter
of a single fiber, or if the ends cannnt be
resolved.
(g) Fibrils attached longitudinally to a fiber are
counted as part of the fiber and the size (width) is
estimated based on the f iber—ro—fjbrjl relationship.
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(h) A fiber partially hidden by grid wires (one or two
sides of the grid opening) is counted, but labeled
as an X—fiber (X—F) in the structure column. If the
number of X—fibers is high enough to affect the size
distribution (mass, etc.), a large—mesh EM grid
should be used, such as 100 mesh (about 2fl0 jm...
wide).
(9) Sizing rules for asbestos structures are:
(a) For fibers, widths and lengths are obtained by
orienting the fibers to the inscribed circles on the
fluorescent screen. Since estimates are within
±1 inn, snail—diameter fibers have greater margins of
error. Fibers less than 1 inn at the fluorescent
screen magnification level are characterized as
being 1 mm. A cylindrical shape is assumed for
fibers. X—fibers are sized by measuring their
entire visible portions in the grid opening.
(b) Bundles and clusters are sized by estimating their
widths and lengths. The sum of individual diameters
is used to obtain the total width, and an average
length for the total length. A laminar—sheet shape
is assumed, with the average diameter of the
individual fiber as the thickness.
(c) Matrices are sized by adding the best estimates of
individual fiber components. A laminar or sheet
Structure is assumed for volume calculation.
(10) The methnd of sizing is as follows:
(a) An asbestos structure is recognized, and its
location in the rectangular “gate relative to the
sides, inscribed circles, and other partaculates is
memorized.
(b) The structure is moved to the center for SAEI)
observation and sizing.
(c) Sizing is performed using the inscribed circles. If
the structure, such as a fiber, extends beyond the
rectangular gate (field of view), it is superimposed
across the series of concentric circles (several
times, if necessary) until the entire structure is
measured.
(d) The structure is returned to its original location
by recall of the location, and scanning is
continued.
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Analytical Procedure—
The analytical procedure is as follows:
(A) EM grid quality is assessed at 250X.
(2) Particulate loading is assessed at 1000X.
(3) A grid opening is selected at random, examined at lOflOX,
and sized.
(4) A series of parallel traverses is made across the grid
opening at the film magnification of 20,()C)OX. Starting
at one corner, end using the tilting section of the
fluorescent screen as a ‘gate” or chute, ” the grid
opening is traversed. Movement through the gate ” is not
continuous, but rather is a stop/go motion. On reaching
the end of one traverse, the image is moved the width of
one “gate,” and the traverse is reversed. These parallel
traverses are made until the entire grid opening has been
scanned.
(5) Asbestos structures are identified morphologically and
counted as they enter the “gate.”
(6) The asbestos structure is categorized as fiber (with or
without X—) bundle, cluster, or matrix, and sized through -
use of the inscribed circles.
(7) The structure (Individual fiber portion) is centered and
focused, and the SAED pattern is obtained through use of
the field—limiting aperture.
(a) SAET) patterns from single fibers of asbestos
minerals fall into distinct groups. The chrysotile
asbestos pattern has characteristic streaks on layer
lines other than the central line, and some
streaking also on the central line. Spots of normal
sharpness are present on the central layer line and
on alternate lines (that is, 2nd, 4th etc.) The
repeat distance between layer lines is about 0.53 nm.
(b) Mtphibole asbestos fiber patterns show layer lines
formed by very closely spaced dots, and have repeat
distances between layer lines also of about 0.53 nm.
Streaking in layer lines Is occasionally present due
to crystal structure defects.
(c) Transmission electron micrographs and SAEI) patterns
obtained .rith asbestos standard samples should be
used as guides to fiber identification. An example
is the “Asbestos Fiber Atlas” (Mueller et al.,
1975).
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(8) From visual examination of the SAED pattern, the struc-
ture is classified as belonging to one of four cate-
gories: (1) chrysotile, (2) amphibole group (includes
anosite, crocldolite, anthophyllite, tremolite, and
actinolite), (3) ambiguous (incomplete spot patterns), or
(4) no identification. SAID patterns cannot be inspected
for some fibers. Reasons for the absence of a recog-
nizable diffraction pattern include contamination of the
fiber, interference from nearby particles, fibers that
are too small or too thick, and nonsuitable orientation
of the fiber. Some chrysotile fibers are destroyed in
the electron beam, resulting in patterns that fade away
within seconds of being formed. Some patterns are very
faint and can be seen only under the binocular micro-
scope. In general, the shortest available camera length
must be used, and the objective lens current may need to
be adjusted to give optimum pattern visibility for
correct identification. A 20—cm camera length and a lOX
binocular are recommended for inspecting the SAED pattern
on the tilted screen.
(9) The specimen holder is tilted for optimum x—ray detection
(40 tilt for the JEO I.* 100C instrument’s Tracor
Northernl NS 880 analyzer and Kevextt detector). The
categorized asbestos structure is maintained in its
centered position for x—ray analysis by means of the Z—
control.
(10) The spot size of the electron beam Is reduced and
stigmated to overlap the fiber. As an option for STF.M
instruments, the electron bean may be used in the spot
mode and the x—ray analysis performed on a small area of
the structure.
(ii) The EDS is used to obtain a spectrum of the x—rays
generated by the asbestos structure.
(12) The profile of the spectrum is compared with profiles
obtained from asbestos standards; the best (closest)
match identifies and categorizes the structure. The
image of the spectrum may be photographed, or the peak
heights (Na, Mg, Si, Ca, Fe) recorded for normalizing at
a later time. No background spectra or constant acquisi-
tion time is required since the shape of the spectrum
(profile) is the criteria. Acquisition of x—ray counts
may be to a constant time; to a constant peak height for
a selected element, such as silicon (1.74 key); or just
* JEOL (U.S.A.) Inc., 11 Dearborn Road, Peabody, Mass. 01960
I Tracor Northern inc., 2551—T.W. Beltway Itwy., Middleton, Wis. 53562
TI Kevex Corp., Chess Dr., Foster City, Calif. 94404
55
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long enough to get an adequate idea of the profile of the
spectra, and then aborted. Figure All illustrates
spectra obtained from various asbestos standards and used
as referenced profiles.
(13) Th specimen holder is returned to 0° tilt to examine
other asbestos structures.
(14) Scanning is continued until all structures are
identified, measured, analyzed, and categorized in the
grid opening.
(15) Additional grid openings are selected, scanned, and
counted until either the total number of structures
counted exceeds 100 per known area, or a minimum of 10
grid openings has been scanned, whichever is first.
(16) The TEM data should be recorded in a systematic form so
that they can be processed rapidly. Sample information,
instrument parameters, and the sequence of operations
should be tabulated for ease in data reduction end
subsequent reporting of results. Figure A12 shows an
example of a data sheet used in Level II analysis.
Figure A9 illustrates the method of scanning a full—grid opening. The
“field of view” method of counting, which is based ott randomly selected fields
of view, has been discontinued. Originally, the method was recommended for
medium loading level, on the filter (50 to 300 fibers per grid opening).
However, if samples are collected at three different loading levels and the
optimum is selected, this medium loading on the filter will not be used.
Samples with grid openings containing 50 to 300 fibers may be used as
laboratory fiber preparations or selected source samples, but in field
samples 1 the particulate loading is usually of much higher concentration than
the fiber. Filter loading is characterized by particulate concentration, not
by fiber concentration.
EDS is relatively time—consuming, and becomes redundant If used as
repetitive analysis for a confirmatory check on chrysotile fibers. Chrysotile
identity by morphology and visual SAET) analysis Is not as controversial as
amphibole identification and categorization.
The following rules are recommended for EDS analysis (Level 11):
(1) For chrysotile structure identification, the first five
are analyzed by EDS, then one Out of every 10.
(2) For amphibole structure identification, the first 10 are
analyzed by EDS, then one out of every 10.
(3) For amphibole structure identification and categorization,
all confirmed amphiboles are analyzed by E1)S.
(4) For ambiguous structure identification and categorization,
all are analyzed by E1)S.
56
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Energy dispersive x—ray analysis as used in asbestos analysis is
seniquantitative at best. X—ray analyzer manufacturers may claim quantitative
results based on calibration standards and sophisticated computer software,
but such claims are based on stoichiometric materials and extension of work
with XRF instrumentation. A bestos has a varying elemental composition. The
electron beam in an EM is of varying size, and not all inatruments are
equipped to measure the beam current hitting the specimen. The size of the
specimen has an effect on the X—ray output, and nearby materials may fluoresce
and add to the overall x—ray signals being generated. iloreover, specimen
tilting results in a loss of x—ray acquisition from particles hidden by grid
wires or by other particles.
The only consistency in x—ray analysis is that the intensity of the
output, within restrictions, is proportional to the mass, therefore providing
the serniquantitative analytical possibility. Asbestos minerals have been
found to have a characteristic profile, although not an exact duplicate of
each other. For example, the Mg:Si ratio of chrysotile may vary from 5:10 to
10:10, averaging about 7:10. The ratio can be used to confirm the morphology
and visual SAED analysis.
Table 1 illustrates the phenomena of variability with resemblance for
some of the amphibole fibers. Peak heights and profile measurements were
taken.
To aid in the visual perspective of the spectrum profile, the peak
heights were normalized to a silicon value of 10, resulting itt a five—number
series that is relatively easy to visualize——as in the following examples:
chrysotile — 0—7—10—0—0
tremolite — 0—4—l0—3—(1
crocidolite — 1—1—10—0—6
anchophyllite 0—3—10—0—1
arnosite — 0—2—10—0—7
These relationships are approximate, since chrysotile can vary from 0—5—10—0—0
to 0—10—10—0—0. } owever, for the others, the variation is only about one
point, such that the profile (shape) of the five elements (Na, Mg, Si, Ca, Fe)
is recognizable.
5. Data Reduction and Reporting of Results
Data Reduction—
From the data sheet, size measurements are converted to microns (16,000x
screen magnification), mass of asbestos structure is calculated, and other
characterizing parameters are calculated through use of a hand calculator or
computer. (Appendix C, an example of a computer printout from Level 11
analysis, shows reduced data——that is, what was found on the specified number
of grid openings or area examined.) These measurements are summarized and
related to the volume of air sampled and the total effective filtration area
57
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TABLE I. PROFILE MPAR 150$ OF ASB ESTOS STAJIDAR.OS
Asbestos Type Site. u St Ce Ps Profile
Amosite (CI—38A) 0.19 x 1.44 (stigeate ’ 182 497 386 0—4—10—0—8
0.19 x 0.75 (STEM) 116 3Z — 31? 0-4— 1 0—fl—?
0.19 x 1.25 LP1 352 289 0—5— 1 0—C—S
0.19 a 0.88 (100 a) 226 870 674 O—3—1fl—0— R
0.25 a 1.81 (100 a) 376 4207 3338 0—1—l0—O—R
0.12 a 1.56 253 2049 1515 0—1—10—0—7
0.31 a 2.38 256 2127 1413 0—j— ifl—O—8
0.19 a 1.56 274 1696 1116 0—2—10-0—7
Repeat 477 2945 1959 0—2—10—0—7
Anthophyllite (Ar—iS) 0.56 a 2.38 (stigmate) 631 t 2577 349 0—2—In—fl—i
0.31 a 2.38 (stigmate) 640 1670 71 0—4—10—0—0
0.31 a 5.19 (stigmate) 1064 3610 464 0—3—10—0—1
0.19 a 1.56 (stigmata) 507 2191 309 0—2—In—fl—I
0.19 a 1.88 (stigmata) 787 2286 257 0—3— 1 0—0—1
Crocidolite (CR—37) 0.19 a 0.81 (stigmata) 131 100 885 501 2—1—10—0—6
0.06 a 0.50 (stigmata) 28 28 205 £15 i— I— t O— I l— A
0.06 a 0.69 (stigmata) 37 35 171 96 2—2—10—0—6
0.12 a 1.00 (stigmata) 44 53 37Q 204 1—1— 10—0—S
Repeat (STEM) 70 64 812 333 1 11005
0.12 a 0.62 (stigmata) 56 65 479 260 1—1—10—0—5
0.12 a 1.12 (stigmata) 53 56 326 166 2—2—10—0—5
049 a 1.56 (stIgmata) 78 83 735 421 1—1—10—0—6
0.06 a 1.69 (stigmata) 45 48 290 159 2—2—10—0—6
Repeat (STEM) 72 85 892 463 1— 1— 10—0— S
Repeat (STEM) 35 42 373 237 1—1—10—0—6
Repeat (STEr I) 16 22 166 104 1—1—10—0—6
Tremollte (1—79) 0.38 a 2.19 (atigmate) 138 368 93 0—4—10—2—0
0.38 a 2.19 (spot) 114 327 40 0—4—10-7—0
0.25 a 1.75 (stigmata) 80 197 65 0—4—10-3—0
0.25 a 1.75 (spot) 95 252 62 0—4—10—2—0
Repeat (stigmate) 70 211 51 0—3—10—2—0
(STEM—tOO a) 376 1118 245 1—3—1 0—2—0
(STEM—100 s) 135 364 72 0—4-10—2—fl
(SrEpi—100 s) 145 4810 1235 0—3—In—3—0
(STUs—100 a) 64 1 1 48 0—3— 10—2— U
(STrii—100 s) 1072 3114 P2 0— 1—10—3— f l
(STCtf—40 a) 46 123 27 0— 4—1 0—2—0
(STF.M—40 a) 123 333 94 0— 4—1 0- 1—fl
58
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(area of deposit). Size measurements of X—fibers may be doubled and noted, or
kept as a separate category.
Fiber number concentration is calculated from the equation
Total no. of fibers
Fibers/rn No. of EM fields
Total effective filter area, cm 2
x
Area of an EM field, cm
I
X Volume of air sampled, i n 3
The number of X—fibers, bundles, clusters, and matrices are calculated in a
similar manner. X—fibers may be included wi th fibers if they are few in
number. Similarly 1 their corresponding mass (from their size measurements)
may be included.
Fiber mass for each type of asbestos (chrysotile or amphibole) in the
sample is calculated by assuming that both chrysotiles and amphiboles have
circular cross—sections (cylindrical shape) and that the width measurements
are one diameter. The density of chrysotile is assumed to be 2.6 glen 3 , and
of arnphiboles to be 3.0 g/cm 3 . The individual mass is calculated from the
equation
Mass, iig — x (length, m) x (diameter, Urn) 2
x (density, g/cm 3 ) x 1(16
The total mass concentration of fibers for each type of asbestos is then
calculated from the total mass of all the individual fibers of that type.
The individual masses of bundles, clusters, and matrices are calculated
by assuming a laminar or sheet—like structure with an average thickness of the
fiber make—up of the structure. Again, the density of chrysotile is assumed
to be 2.6 gfcm 3 , and of amphiboles to be 3.fl g/cm 3 . The individual masses are
calculated from the equation
Mass, ig — (length, urn) x (width, urn) x (thickness, m)
x (density, g/cm 3 ) x 1(16
The total mass for each type of structure for each type of asbestos is the sum
of all the individual masses.
59
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Other characterizing parameters of the asbestos structures are: (1)
length and width distribution of fibers, (2) aspect ratio distribution of
fibers, and (3) relationships of fibers, bundles, clusters, arid matrices.
Reporting of Results—
The data and their subsequent reduction are reported as summarized, or
can be further reduced to present the interrelationships of the various
characterizing parameters. Figure *13 is an example of the EN data report;
Figure *24 is an example of the sample summary report.
The methodology can establish the limits of identity for unknown samples,
act as a OC/QA method for Level I analysis, and satisfy most of the
identification criteria for asbestos.
6. Quality Control /Quality Assurance
Sampling procedures will vary depending on the type of sample, objectives
of the sampling, and tine/cost factors. The primary goals of sampling are to
obtain a representative sample at the location and time of sampling, and to
maintain sample integrity. The sampling team will have written sampling
procedures, and the field chief and/or designated individual will be respon-
sible for all record—keeping (including sample identification, labeling,
logging of data, site description, and meteorological conditions), are— and
post—collection checks, and continuous sample custody and sign—outs until the
sample is delivered to the laboratory and transferred to the appropriate
quality assurance officer (0*0). Verification of sampling times, flow rates,
equipment calibration, and taking of field blanks will be checked and recorded
in the field logbook.
Samples are turned over to the QAO for logging into a project logbook.
Each sample is carefully examined for gross features, such as tears, breaks,
and overall condition of container. The QAO registers the as—received sample
number and other designated information, and assigns a simple internal code
number that will accompany the sample through the preparation stage, grid
transfer, grid analysis, data reduction, and reporting of results.
After being logged into the project logbook, the sample is transferred to
the custody of the electron microscopy staff, where every precaution is taken
to maintain sample integrity and to prevent contamination and loss of
collected particulates. During storage and transport, the filters in their
respective holders are maintained in a horizontal position at all tines.
The sample logging, handling, and storing procedures ensure that all
samples can be readily located and identified throughout the course of a
program. The 0*0 has divisional responsibility for oc/oA activities, and must
see that the laboratory maintains high standards. He must be aware of current
standards of analysis, and must ensure that internal quality control
standards, instrument calibration, and records of samples and completed
analyses are kept for ease of later retrieval and use.
60
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For quality control, internal laboratory blanks are analyzed at least
once a week, which ay or ay not coincide with a aa p1e batch blank. In
addition, a magnification calibration of the EM using a carbon grating replica
(2,160 lines per mm) is performed once a week. The results are recorded in an
EM instrument log, along with other routine instrumental performance checks.
All photographs, TEll, SEll, and STEM images are recorded in a photo log. These
QC results are documented for inspection by the QAO.
61
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UT RCSEARCH INSTITUTE STRUCTURE ANALYSIS tiATA
INIIYVI DUAL OI’.J CT tIATA TABI E (F=rI hER, ts=UIJNL’LC, C=CLUSTER , H=MATRIX)
TABLE RCPARATION IuATE 11—OCT—85
n = = a = = = = = = = = = = = = = == = = = a == = = = = = = = = = = = == = Cr = = = = = an = = = = = = = = = = = = = = = = = = = == = = = = == = = = = == = = = a a
SAMPLE COt’E C06610-0i20 ( o.€-A1— 3/
Size (Micron) Mass (Picogram)
Ord Not No
O n Oh.., Str Llepth Width Length Ratio Chr soti1e Am hihoIe Ambi Asbe Patt X-Ra s
i 0.0 :;; -;; - :; :- ..
8 2 F 0.000 0.625 5.94 9.5 • 5.464 • • . (I)
9 3 F 0.000 1.250 5.13 4.1 . • . X •
11 4 r 0.000 0.250 2.01 11,3 • 0.414 . . • >V)
15 5 F 0.000 0.375 2.75 7.3 • 0.911 . . .
15 6 F 0.000 0.625 4.37 7.0 • . . X • I’l
16 7 F 0.000 0.107 1.19 6.3 • 0.098 . . .
17 8 F 0.000 0.250 1.87 7.5 • 0.276 . . • r-’i
17 9 F 0.000 0.250 3.50 14.0 • 0.515 . • .
17 10 C 0.187 0.012 5.31 6.5 • 2.428 • • . •—•
17 11 F 0.000 0.107 1.00 5.3 • 0.083 • • . > —4 ><
19 12 F 0.000 0.562 6.07 12.2 • 5.125 • • •
19 13 F 0.000 0.375 5.94 15.8 • 1.967 • . . —4
m (Mm
Total Mass (Picogram) 0.000 17.293 (i (I)
Total Count 0. 11. 0. 2. 0.
1 -
-------
ITT RESEARCH INSTITUTE STRUCTURE ANALYSIS [ ‘AlA
SINGLE SAMPLE SUMMARY TABLES
SAMPLE COPE: C06610-0120 TABLE PREPARATION I’ATC 11—OCT-05
Samrle Collection and Preparation Data
Air Volume = 1.00 Cu H
[ ‘eposit Area = 1 ,00 So Cm
Ashed Area = 1.00 So Cm
Redeposit Area = 1.00 So Cm
Grid [ ‘ata
Grid x l i: MISC *19/C3 + C4
Individual Grid fl enin1 = 0.000062 Sn Cm
Number nf Grid Openir.fl = 20
Film Ma snification 20000
Obaect
Structure
Fiber
Aerosol Oh ect Count And Calculated ObJect Mass Characteristics
T e
Chrvsoti le
Amphibole
Other
All Fiber
C .,
(A)
Actual
Ob ect
Count
Number
Concen.
(Number
Per Cu N)
Mnsc
Concen.
CPicnilrem
Per Cu N)
0 .
10.
2.
0.
8057 ,
16 1 1 .
0.0
11976.6
12.
9668.
Aver a e
Width
(Micron)
0.00 1 0.00
0.31 1 0.17
0.94 1 0.44
0.42 1 0.32
Cluster Chr&sotlle
Amphibole
Other
All Cluster
Ave ra!le
Ler.ilth
(Micron)
0.00 1 0.00
3.31 1 2.20
4.75 1 0.53
3.55 & 2.07
0.
1.
0 .
1.
Ave ra 1e
L er,iJ th
To Width
Ratio
0.00 1 0.00
10.83 1 4.47
5.55 + 2.05
9.95 & 4.57
0.
806.
0.
806.
0.0 0.00
1956.2 0.01
0.00
1 0.00
1 0.00
+ 0.00
0.00 4 0.00
0.00 & 0.00
5.31 1 0.00
0.00 & 0.00
6.54 1 0.00
0.00 1 0.00
0.81 1 0.00 5.31 & 0.00
6.54 & 0.00
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APPENDIX C
STATISTICAL METHOD
The statistical significance of the observed difference between results
obtained by PCM and TEM analyses of samples collected under nonaggressive and
aggressive conditions and the difference between nonaggressive and aggressive
sampling conditions obtained by PCMaand TEM analyses was determined through
the application of the Mann-Whitney test. The Mann—Whitney test was selected
from among several procedures for hypothesis testing because its application
does not require any prior knowledge of the underlying probability distribution
function of the data. A cursory inspection of the data suggests a positive
skewness (i.e., a few values that are very high compared with the other
members of a data set). For this reason, the geometric mean, rather than the
arithmetic mean, was used as a measure of central tendency.
Mann-Whitney is used to test the null hypothesis that two different
samples were taken from the same population. Rejection of the null hypoth-
esis implies that the two samples are from two different populations. The
test assumes that sample A consists of m observations and sample B consists
of n observations, where n < m. The data values from the two samples are
ranked into a single set with rn + n observations. The statistic I is calcu-
lated next; this is the sum of the ranks of the values in sample B. Finally,
it is necessary to determine the probability that the calculated value of T
would differ as much or more from the expected value of T for the v i + n
observations. Tables of exact probabilities of T are available for small
values of m and n. In situations where m and n are not small (as is the case
with the data from this study), the normal approximation can be used to
calculate the necessary probability. When this probability is small (i.e.,
less than 0.05), the null hypothesis is rejected.
As an example, consider the data in Table C—i, which shows results
obtained by TEM under nonaggressive and aggressive sampling conditions.
The conclusion is that the probability that I would be greater than or
equal to 121.5 for a sample of n 9 when m = 9 is 0.001. This is sufficient
cause to reject the null hypothesis that the two sets of data were taken from
a single population. On this basis, it is concluded that aggressive sampling
yields concentrations of fibers that are much higher than those measured
under nonaggressive sampling.
a Mosteller, F., and R. E. K. Rourke. Sturdy Statistics, Nonparametric and
Order Statistics, Addison—Wesley. 1973. pp. 54-88.
64
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TABLE C-i. APPLICATION OF THE MANN-WHITNEY TEST TO NONAGGRESSIVE AND
AGGRESSIVE RESULTS OBTAINED BY TEM
Nonaggressive
Aggressive
Value
Rank
Value
Rank
<0.005
0.006
0.006
0.010
0.011
0.012
0.016
0.017
0.028
1
2.5
2.5
4
5
6
7
8.5
13
0.017
0.022
0.024
0.025
0.041
0.041
0.059
0.060
0.104
8.5
10
ii
12
14.5
14.5
16
17
18
T = 121.5
m= 9
n=g
= 3.18
2 =
aT
1.11 =
n
(m + n +
1)
2
9
(9 + 9 +
2
1)
n
m
(m
+ n +
1)
12
(9)(9)(9 + 9
+ 1)
= 85.5
121.5 - 85.5
11.32
= 128.25
a 1 = 11.32
p = 0.001
65
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APPENDIX D
COMPARISON OF NONAGGRESSIVE AND AGGRESSIVE ASBESTOS SAMPLiNG RESULTS
Figures D-1 and D-2 show graphical comparisons of sample results taken
under nonaggressive and aggressive post—abatement conditions. These figures
clearly demonstrate that asbestos fibers and structures measured under ag-
gressive conditions are higher than those measured under nonaggressive condi-
tions.
66
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I I I I I FtI(
I I I F I Ilif
1 - 1 —f I I III
LEGEND
CHRYSOTILE FIBER
* AMPHIBOLE FIBER
I I I Ill I
0. 1
I I I II 1111
1
I I liii
10
FIBER DIAMETER, micrometers
Figure D .1. Plot of fiber length and fiber diameter for a non-
aggressive post-abatement air sample in Room 157.
PCM METHOD
7400
10
U,
I-
c i
E
C
S.-
U
•1
E
I-
w
-J
LiJ
*
0.1 —
0.01
67
-------
1 I I 1 11111
I I I I •W’I III
1 I I I i11I
* *
*
I I I I ti_Il!
1
LEGEND
L CHRYSOTILE FIBER
* AMPHIBOLE FIBER
* AMBIGUOUS FIBER
I I I I I l1_I_
10
FIBER DIAMETER, micrometers
Figure D-2. Plot of fiber 1en th and fiber diameter for an
aggressive post-abatement air sample in Room 157.
PCM METHOD
7400
1*
**
*
‘I;.
*
10
1—
*
*
*
*
I-
a)
4-)
0)
C
1
U
..-
E
I-
LU
-J
I -I . ’
*
*
*
0.1 —
0.01
I I I 11111
0.1
68
-------
TECHNICAL REPORT DATA
(Please read lns:rijcrsons on the reverze before corn pie sing)
REPORT ND 12
3 RECIPiENT S ACCESSION NO
4 TITLE ANDSUBTITLE Assessment of Assay Methods for
Evaluating Asbestos Abatenient T chnology at the
Corvallis Environmental Research Laboratory
REPORT DATE
PERFORMING ORGANIZATION CODE
‘7 AUTI4ORIS) Mark Karaffa, Robert Amick, Ann Crone, and
Charles Zimer
I PERFORMING ORGANIZATION REPORT NO
—
9 PERFORMING ORGANIZATION NAME AND ADDRESS
PEI Associates Inc.
Cincinnati, OH 45246-0100
10 PROGRAM ELEMENT NO
L104
11 CONTRACY/9 ( % (
68-03 -3197
12 SPONSORING AGENCY NAME AND ADDRESS
Water Engineering Research Laboratory - Cincinnati
Cincinnati, Ohio 45268
13 IYPE OF REPORT AND PERIOD COVERED
Complete
14 SPONSORING AGENCY CODE
EPA. 600/14
15 SUPPLEMENTARY NOTES
William C. Cain was the EPA project officer (513-569-7559).
lb *UST Ac1
Air sampling was conducted at an EPA office building which had undergone an
asbestos abatement program. The aggressive sampling technique revealed that
air-entrainable asbestos remained in work areas after completion of abatement
actions. The ratio of aggressive to noriagressive PCM fiber concentrations was
7.0, whereas this ratio was 3.7 for TEfr1 analyses. Study results also confirm that
under similar sampling conditions, TEM analysis detects more fibers than PCM
because of TEM’s better resolving capability. The ratio of TEM/PCM concentrations
for nonagressive sampling was 3.0 for ambient samples and 3.3 for indoor samples;
the ratio for agressive sampling was about 2. Because the PCM method does not
discriminate between asbestos and other fibers and cannot resolve fibers thinner
than about 0.2 pm, PCM results may not accurately reflect the true hazard potential.
KEY WOADSAN000CUMENTANALYSIS
DESCRIPTORS bIDENTIFIERS’OPEN ENDED TERMS C COSATI Field/Group
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.
Release to Pubi c
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Unclassified
71 NO OF PAGES
77
20 SECURITY CLASS jTIn:po ,
Unclassified
22 PRICE
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