f/EPA
United States
Environmental Protection
Agency
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Environmental Sciences Research- _
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Research Triangle Park NC 27711 */1 \
Research and Development
EPA-600/S3-82-008 June 1982
Project Summary
V
Feasibility of Developing
Source Sampling Methods for
Asbestos Emissions
W. M. Henry, G. M." Sverdrup, E. W. Schmidt, and S. E. Miller
The objective of this program was to
determine the feasibility of developing
methods for sampling asbestos in the
emissions of major asbestos sources.
The sources of concern are: (1) ore
production including asbestos mining
and milling and taconite production,
(2) asbestos-cement production, (3)
asbestos felt and paper production,
and (4) the production of asbestos-
containing friction materials. Potential
sampling methods must provide sam-
ples compatible with the provisional
analysis methods using electron micro-
scopy (U.S. EPA Report No. 600/2-
77-178).
Visits to the four industries revealed
that asbestos emissions can be divided
into two classes: stack and fugitive.
Inherent differences between stack
and fugitive emission environments
may necessitate the development of
two techniques or at least two modifi-
cations of a general technique for
sampling. A development program for
sampling methods is feasible, given
the nature of the emissions and
potential sampling environments
observed in the industry survey.
It is not feasible to undertake a
methods development program for
strict compatibility with the recom-
mended procedure of the provisional
analytical method. Strict compatibility
requires the collection of a uniform
deposit of proper loading by air
filtration on a 0.4 /urn pore si?e
polycarbonate filter. However, methods
development programs are feasible if
the sampling method is to be compa-
tible with the* alternative procedures
of the provisional method or general
electron microscopy. Such procedures
require that the collected sample be
transferable to an electron micro-
scope grid for'counting. The method
of sample collection is not precisely
specified.
Viewed on the basis of components,
the essential areas for research toward
method development concern collec-
tion techniques and removal of non-
asbestos material. Practical options
for the collection technique compo-
nent are limited to either electrostatic
precipitation or collection by cellulose
ester, or polycarbonate filters, despite
their known limitations. These techni-
ques may be supplemented by precol-
lection with an impinger to reduce
loading. The usefulness as well as the
feasibility of a separation during
sampling can be assessed only after
more thorough data characterizing the
industry emissions are obtained and
evaluated. The application of inlet and
probe technology appears to be a
straightforward engineering task.
This Project Summary was devel-
oped by EPA's Environmental Sciences
Research Laboratory, Research Tri-
angle Park. NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
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Introduction
Asbestos has been identified as a
hazardous air pollutant and is therefore
subject to a National Emission Standard
for Hazardous Air Pollutants (NESHAP).
However, a numerical standard has not
yet been promulgated, partly because of
the absence of a reference source
sampling method for asbestos emissions
and a reference method for the analyti-
cal determination of asbestos in collected
samples. A provisional analytical method
has been established based upon
electron microscopy (EPA/600/2-77-
178). Research is continuing on the
establishment of a reference analytical
method based upon the current provi-
sional method. This project is the first
phase of research leading toward the
possible development of a reference
source sampling method for asbestos
emissions.
The objective of this program was to
determine the feasibility of developing
methods for sampling asbestos in the
emissions of major asbestos sources.
The sampling methods must provide
samples compatible with the provisional
analysis methods. Information was
gathered to make estimates of the time
and effort required to develop methods.
Conclusions
After each of the key system compo-
nents of a sampling system was
reviewed, it was concluded that the
development of a standard method for
sampling asbestos emissions is feasible.
The study did not uncover any limiting
industry anomalies or insurmountable
technical problems.
It is not feasible to undertake a
methods development program for strict
compatibility with the recommended
procedure of the provisional analytical
method. Strict compatibility requires
the collection of a uniform deposit of
proper loading by air filtration on a 0.4
fjm pore size polycarbonate filter.
However, methods development pro-
grams are feasible if the sampling
method is to be compatible with the
alternative procedures of the provi-
sional method or general electron
microscopy. Such procedures require
that the collected sample be transfer-
able to an electron microscope grid for
counting. The method of sample collec-
tion is not precisely specified.
Inherent differences between stack
and fugitive emission environments
may necessitate the development of two
sampling techniques or at least two
modifications of the same technique.
Viewed on the basis of components,
the essential areas for research toward
method development concern collection
techniques and removal of nonasbestos
material. Practical options for the
collection technique component are
limited to either electrostatic precipi-
tation or collection by cellulose ester or
polycarbonate filters, although each of
these options possesses negative
features for the overall sampling and
analysis procedure.
The negative features of cellulose
ester filters include high pressure drop
and sample losses in the transfer of
collected asbestos to an EM grid. The
negative features of polycarbonate
filters include less than 100 percent
collection efficiency and the tendency
for collected asbestos to become de-
tached from or to move around on the
filter during handling operations. These
collection techniques may be supple-
mented by precollection with an im-
pinger to reduce loading. Past experi-
ence of analysts indicates that asbestos
and nonasbestos material can be
separated from each other in the
laboratory; however, ashing, sonication,
and two-phase liquid separation techni-
ques can alter the asbestos size distri-
bution. The usefulness as well as the
feasibility of a separation during sam-
pling can be assessed only after more
thorough data characterizing the indus-
try emissions are obtained and evaluated.
The application of inlet and probe
technology appears to be a straight-
forward engineering task.
Recommendations
A development program for a source
sampling system should proceed on the
basis of components. This would entail
pursuit of research both on collection
techniques and extraneous material
separation during sampling. Subse-
quently the most promising of the
techniques should be incorporated with
each component and with state-of-the-
art inlet and probe designs to form a
sampling system. Finally the complete
system must be checked in the laboratory
and demonstrated in the field.
Investigation of collection techniques
should center on electrostatic collectors
and on collection by cellulose ester and
polycarbonate filters, despite the limita-
tions of each of these options. More
industrial data characterizing the extra-
neous material need to be obtained to
assess whether a development program
for removal of extraneous material
should focus on separation during
sampling, in the laboratory, or both. The
advantages of precollection with im-
pingers or other means to reduce
loading should be evaluated experi-
mentally.
Determination of Criteria and
Constraints
A source sampling method for asbestos
emissions must meet certain require-
ments if it is to be accepted as an
approved sampling method. Two stan-
dards upon which to base a judgment of
acceptability were determined at the
outset of the program. The first criterion
is that the sampling method must be
capable of collecting a representative
asbestos size distribution from the local
environment. The second criterion is
that the asbestos must be collected so
that it can be analyzed by the provisional
analytical method to provide the required
determinations.
A number of constraints arising from
different sources restrict potential
sampling methods if they are to meet
the two basic criteria. The establishment
of these constraints provided the
framework for the conduct of the
feasibility study on the development of a
source sampling method.
After identification of general con-
straints on a sampling method, the
following factors were reviewed:
• characteristics of asbestos fibers
• composition and magnitude of
emissions potentially containing
asbestos
• characteristics of potential sampling
environments
• current source sampling methods
• analytical methods for asbestos
determinations
• adaptability of particle collection
methods for asbestos.
The evaluation included a literature
review and site visits to the four
industries. Consideration of the findings
of the overall review coupled to the two
general criteria for a source sampling
method led to the identification of the
constraints on a method for asbestos.
They are:
• A single collector cannot be used
simultaneously to collect asbestos
over the diameter range 0.03 to 10
fim and to provide optimum loading
for both number and volume con-
centrations by counting.
• The potential breakup of fiber
bundles must be minimized by
providing a short, straight transport
path between the sampling inlet
and the collector.
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• The difference in air velocity be-
tween stack and fugitive emission
environments necessitates the
development of at least two sam-
pling techniques designed for air
velocities in the two types of
environments.
• Saturated conditions will be en-
countered. The sampling system
must be able to collect samples in
these environments.
• A continuous monitor to assess the
level of asbestos loading in the
collector is not practical. A series of
sample volumes should be collected
separately to provide one with an
acceptable loading.
• Strict compatibility with the recom-
mended practices of the provisional
method is not possible if collection
methods other than air filtration by
polycarbonate filters are to be
considered.
• If the sampling method is to be
strictly compatible with the provi-
sional analytical method, the sam-
pling rate through the filters must
be within the range for optimal
filtration by a polycarbonate filter.
• Direct air filtration or filtration of a
liquid containing collected asbestos
is feasible. Uniform electrical
deposition of asbestos on a surface
needs further research.
• The size and chemical character-
istics of the asbestos and non-
asbestos particulate emissions
preclude the use of inertia! or
magnetic forces in a sampling
system for material separation. It is
highly probable that material sepa-
ration techniques will need to be
used during sample preparation.
Elevated temperature is not a con-
straint.
Feasibility of Method
Development
The feasibility of conducting a devel-
opment program for an asbestos source
sampling method was determined by
considering four components of a sam-
pling system. These components are: (1)
system inlet, (2) transport probe, (3)
extraneous nonasbestos material sepa-
ration, and (4) collection technique.
The current technology for design of
inlets and probes for sampling particu-
late matter is adequate. The application
of this technology to an asbestos sam-
pling method is a straightforward engi-
neering task for both fugitive and stack
sampling applications.
Undesirable nonasbestos material
(extraneous material) will be present in
the sampling environment, thus compli-
cating the measurement of the airborne
asbestos. Ideally, the extraneous mate-
rial should be removed at the time of
sampling to facilitate subsequent
analysis.
Classically, extraneous material has
been removed by employing differences
in either physical or chemical form to
separate the undesired material from
the material of interest. The broad size
range of asbestos present [from the dif-
fusion dominated region (0.03 urn) to
the inertial behavior region (4.0 yum)]
makes complete separation of extrane-
ous material from the asbestos impossi-
ble by traditional mechanical means
such as impactors or cyclones. The
apparent nonhompgeneous form of the
extraneous material makes other types
of separation (such as magnetic or
metallic material) impractical. Thus, at
this time, it would appear that chemical
or pyrolytic separation of the nonasbes-
tos material holds the most promise.
Such techniques are more appropriately
suited to. analytical procedures than
sampling procedures and as such were
not within the scope of this study.
The following collection techniques
were reviewed: (1) direct detection
based on electrical mobility, inertial
separation, and phase distribution of
light scattering and (2) fiber collection
by thermal and electrostatic precipita-
tion, collection by impingers, air filtra-
tion, and collection by cyclones. Practi-
cal options for a collection technique are
limited to air filtration using polycarbo-
nate or cellulose ester membrane filters
or electrostatic precipitation.
W. M. Henry, G. M. Sverdrup, E. W. Schmidt. andS..E. Miller are withBatteHe
Columbus Laboratories. Columbus, OH 43201.
Ken Knapp is the EPA Project Officer (see below).
The complete report, entitled "Feasibility of Developing Source Sampling
Methods for Asbestos Emissions," (Order No. PB 82-196 148; Cost: $9.00.
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
U S. GOVERNMENT PRINTING OFFICE. 1982 -'669-017/0738
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