ASTM D7201-06(2011)
(Practice)Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in the Workplace, by Phase Contrast Microscopy (with an Option of Transmission Electron Microscopy)
Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in the Workplace, by Phase Contrast Microscopy (with an Option of Transmission Electron Microscopy)
SIGNIFICANCE AND USE
Users of this practice must determine for themselves whether the practices described meet the requirements of local or national authorities regulating asbestos or other fibrous hazards.
Variations of this practice have been described by the Asbestos Research Council in Great Britain (8), the Asbestos International Association (AIA) RTM 1 (9), NIOSH 7400, OSHA (Reference Method ID 160), and ISO 8672. Where the counting rules of the latter three methods differ, this is noted in the text.
Advantages
The technique is specific for fibers. PCM is a fiber counting technique that excludes non-fibrous particles from the analysis.
The technique is inexpensive, but requires specialized knowledge to carry out the analysis for total fiber counts, at least in so far as the analyst is often required under regulations to have taken a specific training course (for example, NIOSH 582, or equivalent).
The analysis is quick and can be performed on-site for rapid determination of the concentrations of airborne fibers.
Limitations
The main limitation of PCM is that fibers are not identified. All fibers within the specified dimensional range are counted. Differential fiber counting may sometimes be used to discriminate between asbestos fibers and fibers of obviously different morphology, such as cellulose and glass fiber. In most situations, differential fiber counting cannot be used to adequately differentiate asbestos from non-asbestos fibers for purposes of compliance with regulations without additional positive identification. If positive identification of asbestos is required, this must be performed by polarized light or electron microscopy techniques, using a different portion of the filter.
A further limitation is that the smallest fibers visible by PCM are about 0.2 μm in diameter, while the finest asbestos fibers may be as small as 0.02 μm in diameter.
Where calculation of fiber concentration provides a result exceeding the regulatory standard, non-complia...
SCOPE
1.1 This practice describes the determination of the concentration of fibers, expressed as the number of such fibers per millilitre of air, using phase contrast microscopy and optionally transmission electron microscopy to evaluate particulate material collected on a membrane filter in the breathing zone of an individual or by area sampling in a specific location. This practice is based on the core procedures provided in the International Organization for Standardization (ISO) Standard ISO 8672 (1) , the National Institute for Occupational and Health (NIOSH) Manual of Analytical Methods, NIOSH 7400 (2), and the Occupational Safety and Health Administration (OSHA) Method ID 160 (3). This practice indicates the important points where these methods differ, and provides information regarding the differences, which will allow the user to select the most appropriate procedure for a particular application. However, selecting portions of procedures from different published methods generally requires a user to report that they have used a modification to a method rather than claim they have used the method as written.
1.2 The practice is used for routine determination of an index of occupational exposure to airborne fibers in workplaces. Workplaces are considered those places where workers are exposed to airborne fibers including asbestos. Additional information on sampling strategies, sample collection (including calibration) and use of sample results for asbestos abatement projects is provided in a standard Practice for Air Monitoring for Management of Asbestos-Containing Materials (WK 8951) currently being considered by ASTM subcommittee E06.24. A further practice has been approved for the specific purpose of sampling and counting airborne fibers in mines and quarries (Practice D7200), although the practice herein may also be used for this purpose. The current practice may be used as a means of monitoring occupational exposu...
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Designation: D7201 − 06 (Reapproved 2011)
Standard Practice for
Sampling and Counting Airborne Fibers, Including Asbestos
Fibers, in the Workplace, by Phase Contrast Microscopy
(with an Option of Transmission Electron Microscopy)
This standard is issued under the fixed designation D7201; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope tee E06.24. A further practice has been approved for the
2 specific purpose of sampling and counting airborne fibers in
1.1 This practice describes the determination of the con-
mines and quarries (Practice D7200), although the practice
centration of fibers, expressed as the number of such fibers per
herein may also be used for this purpose. The current practice
millilitreofair,usingphasecontrastmicroscopyandoptionally
may be used as a means of monitoring occupational exposure
transmission electron microscopy to evaluate particulate mate-
toasbestosfiberswhenasbestosfibersareknown a prioritobe
rial collected on a membrane filter in the breathing zone of an
present in the airborne dust. The practice gives an index of
individual or by area sampling in a specific location. This
airborne fiber concentration. This practice may be used in
practice is based on the core procedures provided in the
conjunction with electron microscopy (see Appendix X1) for
International Organization for Standardization (ISO) Standard
3 assistance in identification of fibers.This practice may be used
ISO 8672 (1), the National Institute for Occupational and
for other materials such as fibrous glass, or man-made mineral
Health (NIOSH) Manual ofAnalytical Methods, NIOSH 7400
fibers by using alternate counting rules (see Annex A4).
(2), and the Occupational Safety and Health Administration
(OSHA) Method ID160 (3).This practice indicates the impor-
1.3 Thispracticespecifiestheequipmentandproceduresfor
tant points where these methods differ, and provides informa-
samplingtheatmosphereinthebreathingzoneofanindividual
tion regarding the differences, which will allow the user to
and for determining the number of fibers accumulated on a
select the most appropriate procedure for a particular applica-
filter membrane during the course of an appropriately-selected
tion. However, selecting portions of procedures from different
sampling period. The practice may also be used to sample the
published methods generally requires a user to report that they
atmosphere in a specific location or room of a building (area
have used a modification to a method rather than claim they
sampling), where this may be helpful in assessing exposure to
have used the method as written.
workers handling fiber-containing products.
1.2 The practice is used for routine determination of an
1.4 The ideal working range of this test practice extends
2 2
index of occupational exposure to airborne fibers in work-
from 100 fibers/mm to 1300 fibers/mm of filter area. For a
places. Workplaces are considered those places where workers
1000-L air sample, this corresponds to a concentration range
are exposed to airborne fibers including asbestos. Additional
from approximately 0.04 to 0.5 fiber/mL(or fiber/cm ). Lower
information on sampling strategies, sample collection (includ-
and higher ranges of fiber concentration can be measured by
ing calibration) and use of sample results for asbestos abate-
reducing or increasing the volume of air collected. However,
ment projects is provided in a standard Practice for Air
whenthispracticeisappliedtosamplingthepresenceofother,
Monitoring for Management ofAsbestos-Containing Materials
non-asbestos dust, the level of total suspended particulate may
(WK 8951) currently being considered by ASTM subcommit-
impose an upper limit to the volume of air that can be sampled
if the filters produced are to be of appropriate fiber loading for
fiber counting.
ThispracticeisunderthejurisdictionofASTMCommitteeD22onAirQuality
1.5 Users should determine their own limit of detection
and is the direct responsibility of Subcommittee D22.07 on Sampling andAnalysis
of Asbestos.
using the procedure in Practice D6620. For Reference the
Current edition approved Oct. 1, 2011. Published October 2011. Originally
NIOSH 7400 method gives the limit of detection as 7 fibers/
approved in 2006. Last previous edition approved in 2006 as D7201–06. DOI:
mm offilterarea.Fora1000Lairsample,thiscorrespondsto
10.1520/D7201-06R11.
a limit of detection of 0.0027 fiber/mL (or fiber/cm ). For
This test method is based on NIOSH 7400, OSHA Method ID160, and ISO
8672. Users of thisASTM standard are cautioned that if they wish to comply with
OSHA method ID160 the limit of detection is given as 5.5
one of these specific procedures exactly they should follow that procedure, 2
fibers/mm of filter area. For a 1000 L air sample, this
otherwise they should document the modification
corresponds to a limit of detection of 0.0022 fiber/mL (or
Boldface numbers in parentheses refer to the list of references appended to this
method. fiber/cm ).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7201 − 06 (2011)
1.6 If this practice yields a fiber concentration that does not Recommended Technical Method No.1 (RTM 1)Asbestos
exceed the occupational limit value for the particular regulated International Association (AIA)
fiber variety, no further action may be necessary. If the fiber ID 160 Occupational Safety and Health Administration
concentration exceeds the occupational limit value for a (OSHA)
specific fiber variety, and there is reason to suspect that the ISO 8672International Organization for Standardization
specific fiber variety is mixed with other fibers not covered (ISO)
under the same standard or regulation, the optional method
3. Terminology
specified in Appendix X1 may be used to measure the
concentrationorproportionofthefiberscountedthatareofthe 3.1 Definitions:Descriptionoftermsspecifictothispractice,
regulated variety. in addition to those found in Terminology D1356:
3.1.1 asbestos—a term applied to six specific silicate min-
1.7 The mounting medium used in this practice has a
erals belonging to the serpentine and amphibole groups, which
refractive index of approximately 1.45. Fibers with refractive
have crystallized in the asbestiform habit, causing them to be
indices in the range of 1.4 to 1.5 will exhibit reduced contrast,
easily separated into long, thin, flexible, strong fibers when
and may be difficult to detect.
crushed or processed (5). The Chemical Abstracts Service
1.8 Fibers less than approximately 0.2 µm in diameter will
Registry Numbers of the most common asbestos varieties are:
not be detected by this practice (4).
chrysotile (12001-29-5), riebeckite asbestos (crocidolite)
1.9 This standard may involve hazardous materials,
(12001-28-4), grunerite asbestos (Amosite) (12172-73-5), an-
operations, and equipment. This standard does not purport to
thophyllite asbestos (77536-67-5), tremolite asbestos (77536-
address all of the safety problems associated with its use. It is 68-6) and actinolite asbestos (77536-66-4).
the responsibility of the user of this standard to establish
The precise chemical composition of each species varies
appropriate safety and health practices and determine the with the location from which it was mined. Other amphibole
applicability of regulatory limitations prior to use. For specific
minerals that exhibit the characteristics of asbestos have also
precautionary statements, see Section 7. been observed (6).
1.10 This international standard was developed in accor-
The nominal compositions of the most common asbestos
dance with internationally recognized principles on standard- varieties are:
ization established in the Decision on Principles for the
Chrysotile Mg Si O (OH)
3 2 5 4
2+ 3+
Crocidolite Na Fe Fe Si O (OH)
Development of International Standards, Guides and Recom-
2 3 2 8 22 2
Amosite (Mg,Fe) Si O (OH)
7 8 22 2
mendations issued by the World Trade Organization Technical
Anthophyllite (Mg,Fe) Si O (OH)
7 8 22 2
2+
Barriers to Trade (TBT) Committee.
Tremolite Ca (Mg,Fe) Si O (OH) (Mg/(Mg + Fe ) 0.9 - 1.0)
2 5 8 22 2
2+
Actinolite Ca (Mg,Fe) Si O (OH) (Mg/(Mg + Fe ) 0.5 - 0.9)
2 5 8 22 2
2. Referenced Documents
2+
NOTE 1—Actinolite compositions in which Mg/(Mg + Fe ) is between
0and0.5arereferredtoasferroactinolite.SeeRef. (7)forthefullnaming
2.1 ASTM Standards:
conventions specified by the International Mineralogical Association.
D257Test Methods for DC Resistance or Conductance of
3.1.2 area sample—an air sample collected so as to repre-
Insulating Materials
sent the concentration of airborne dust in a specific area or
D1356Terminology Relating to Sampling and Analysis of
room, which, in the case of this practice, refers to an area or
Atmospheres
room of a workplace.
D1357Practice for Planning the Sampling of the Ambient
Atmosphere
3.1.3 asbestiform—aspecifictypeoffibrousmineralgrowth
D3670Guide for Determination of Precision and Bias of
habit in which the fibers and fibrils exhibit a polyfilamentous
Methods of Committee D22
growth habit and possess high tensile strength and flexibility.
D5337Practice for Flow RateAdjustment of Personal Sam-
All materials regulated as asbestos are asbestiform, but not all
pling Pumps
asbestiform minerals are classified as asbestos. Characteristics
D6620Practice for Asbestos Detection Limit Based on
such as tensile strength and flexibility cannot be ascertained
Counts
from microscopic evaluation.
D7200Practice for Sampling and CountingAirborne Fibers,
3.1.4 asbestos fiber—a fiber of asbestos, which meets the
Including Asbestos Fibers, in Mines and Quarries, by
criteria specified below for a fiber. Phase Contrast Microscopy
Phase Contrast Microscopy and Transmission Electron
(PCM) does not identify fibers as asbestos. Under the light
Microscopy
microscope, a population of asbestos fibers may appear as a
2.2 Other Standards:
mixture of fiber agglomerates, fiber bundles (polyfilamentous
NIOSH 7400National Institute for Occupational Health and
growth, unique to asbestiform fibers), fibers with split ends,
Safety (NIOSH), (Revised 1994)
andsinglefibers,therelativeoccurrenceandfrequencyofeach
type depending on the situation.
3.1.5 aspect ratio—the ratio of the length of a fiber to its
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
width.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
5 6
Available from United States Department of Health and Human Services Available from Asbestos International Association, 68 Gloucester Place,
(HHS), 200 Independence Ave., SW, Washington, DC 20201, http://www.hhs.gov. London, W1H 3HL, England.
D7201 − 06 (2011)
3.1.6 limit of detection—the number of fibers necessary to 4. Summary of Practice
be 95% confident that the result is greater than zero.
4.1 Thesampleiscollectedbydrawingairthrougha25-mm
3.1.7 differential counting—atermappliedtothepracticeof
diameter,mixedcelluloseester(MCE)membranefilter,housed
excluding certain kinds of fibers from the fiber count because
in a conductive polypropylene cassette. After sampling, a
theydonotappeartobemorphologicallyconsistentwithfibers
sector of the membrane filter is converted to an optically
ofaspecificvarietythusmodifyingthedefinitionoffibergiven
transparent homogeneous gel. Fibers longer than 5 µm are
below.
counted by observing them with a PCM at a magnification
between 400 and 500.
3.1.8 fiber—anelongatedparticlethatislongerthan5.0µm,
with a minimum aspect ratio of 3:1, and sometimes also
5. Significance and Use
classified as having a maximum width of 3.0 µm as this latter
dimension may equate to the size of fiber, of the density of
5.1 Users of this practice must determine for themselves
many silicate minerals, capable of penetrating to the lung. An whether the practices described meet the requirements of local
asbestos fiber should further exhibit the asbestiform habit,
or national authorities regulating asbestos or other fibrous
although analysis of airborne fibers by PCM may not be
hazards.
sufficient to determine asbestiform habit.
5.2 Variations of this practice have been described by the
3.1.9 fibril—a single fiber of asbestos that cannot be further
Asbestos Research Council in Great Britain (8), the Asbestos
separated longitudinally into smaller components without los-
International Association (AIA) RTM 1 (9), NIOSH 7400,
ing its fibrous properties or appearances.
OSHA(Reference Method ID160), and ISO 8672. Where the
countingrulesofthelatterthreemethodsdiffer,thisisnotedin
3.1.10 fibrous—a habit of minerals composed of parallel,
the text.
radiating, or interlaced aggregates of fibers, from which the
fibers are sometimes separable.Acrystalline aggregate may be
5.3 Advantages:
referred to as fibrous even if it is not composed of separable
5.3.1 The technique is specific for fibers. PCM is a fiber
fibers, but has that distinct appearance. The term “fibrous” in
countingtechniquethatexcludesnon-fibrousparticlesfromthe
mineralogy is used to describe aggregates of mineral grains
analysis.
that crystallize in a needle-like habit and appear to be com-
5.3.2 The technique is inexpensive, but requires specialized
posed of fibers. Asbestos minerals are fibrous, exhibiting a
knowledge to carry out the analysis for total fiber counts, at
specifictypeoffibroushabittermedasbestiform.However,not
least in so far as the analyst is often required under regulations
all minerals having fibrous habit are asbestos.
to have taken a specific training course (for example, NIOSH
582, or equivalent).
3.1.11 field (of view)—the area within a graticule circle that
is superimposed on the microscope image. 5.3.3 Theanalysisisquickandcanbeperformedon-sitefor
rapid determination of the concentrations of airborne fibers.
3.1.12 habit—thecharacteristiccrystalgrowthformorcom-
bination of these forms of a mineral, including characteristic
5.4 Limitations:
irregularities.
5.4.1 The main limitation of PCM is that fibers are not
identified.Allfiberswithinthespecifieddimensionalrangeare
3.1.13 personal sample—a sample taken by a collection
counted. Differential fiber counting may sometimes be used to
apparatus(membranefilter)positionedinthebreathingzoneof
discriminate between asbestos fibers and fibers of obviously
the subject (near the nose and mouth) such that the collected
differentmorphology,suchascelluloseandglassfiber.Inmost
particles are representative of airborne dust that is likely to
situations, diffe
...
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