ASTM D7200-12
Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in Mines and Quarries, by Phase Contrast Microscopy and Transmission Electron Microscopy

Standard No.

ASTM D7200-12

Release Date

2012

Published By

American Society for Testing and Materials (ASTM)

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ASTM D7200-12

Scope

5. Significance and UseTop Bottom

5.1 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.

5.2 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 ID8201;160), and ISO8201;8672. Where the counting rules of these methods differ, this is noted in the text.

5.3 Advantages

5.3.1 The technique is specific for fibers. PCM is a fiber counting technique that excludes non-fibrous particles from the analysis.

5.3.2 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).

5.3.3 The analysis is quick and can be performed on-site for rapid determination of the concentrations of airborne fibers.

5.3.4 The procedure provides for a discriminate counting technique that can be used to estimate the percentage of counted fibers that may be asbestos.

5.4 Limitations

5.4.1 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.

5.4.2 A further limitation is that the smallest fibers visible by PCM are about 0.2 ??m in diameter, while the finest asbestos fibers may be as small as 0.02 ??m in diameter.

5.4.3 Where calculation of fiber concentration provides a result exceeding the regulatory standard, non-compliance is assumed unless it can be proven that the fibers counted do not belong to a member or members of the group of fibers regulated by that standard.