ASTM International

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

Annotation

This practice2 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)3, 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. 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. This practice further gives guidance on how differential counting techniques may be used to indicate where a population of fibers may be asbestos.

The practice is used for routine determination of an index of occupational exposure to airborne fibers in mines, quarries, or other locations where ore may be processed or handled. The method gives an index of airborne fiber concentration. The method provides an estimate of the fraction of counted fibers that may be asbestos. This practice should be used in conjunction with electron microscopy (See Appendix X1) for assistance in identification of fibers.

This practice specifies the equipment and procedures for sampling the atmosphere in the breathing zone of an individual and for determining the number of fibers accumulated on a filter membrane during the course of an appropriately-selected sampling period. The method may also be used to sample the atmosphere in a specific location in a mine or in a room of a building (area sampling).