WK83115 - New Test Method for Calculating an Airborne Fiber Concentration from Automated Counting of Fibers in Prepared Air Sample Filters using Phase Contrast Microscopy | ASTM
Work Item
ASTM WK83115
New Test Method for Calculating an Airborne Fiber Concentration from Automated Counting of Fibers in Prepared Air Sample Filters using Phase Contrast Microscopy
1. Scope
This method describes the determination of the concentration of fibers, expressed as the number of such fibers per millilitre (or cubic meter) of air in the breathing zone of an individual or by area sampling in a specific location. The method uses samples of airborne particulate material collected on a membrane filter with fiber counting by automated phase contrast microscopy. The fibers determined by this practice are specified by geometry according to counting rules and are limited to those visible under specified conditions of phase contrast microscopy resulting in a determination of concentration (index) that may be compared to workplace risk assessments based on similar methodology. Phase contrast microscopy cannot distinguish fibers of asbestos from fibers of other materials visible under the same conditions. If it is desired to restrict the count of fibers only to those of asbestos and it is suspected that fibers of other materials are present, transmission electron microscopy on a separate portion of the sample can be used to modify the phase contrast microscopy result according to the proportion of asbestos fibers.
Keywords
air monitoring; asbestos; fibers; membrane filter method; phase contrast microscopy; sampling and analysis; workplace atmospheres
