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.
air monitoring; asbestos; fibers; membrane filter method; phase contrast microscopy; sampling and analysis; workplace atmospheres
There is no standard for this type of technology.
The title and scope are in draft form and are under development within this