Phase Contract Microscopy (PCM) Asbestos Air Samples is a method that follows a prescribed standard methodology called the NIOSH 7400 Method.
PCM uses a light microscope to visually detect fibers. The microscope can be hand carried; one of the advantages of this method is mobility. Samples can even be analyzed on-site, which decreases the turnaround time required for obtaining results. The microscope magnifies objects approximately 400 times their actual size.
The main disadvantage of the Phase Contrast Microscopy methodology is that it is not asbestos specific. The analyst counts any fiber that falls into a field of view that is greater than or equal to 5 μm in length, with a 3:1 aspect ratio(three times longer than its width).
You need to be aware of this when requesting that we analyzing this type of sample. Items such as carpets, wood, fiberglass, and drywall can produce fibers that fall in this size range and will be counted along with asbestos fibers in determining exposure.
PCM is generally cheaper for the lab to process but there are multiple drawbacks as well as advantages of this method. Some projects may require both TEM and PCM sampling for valid clearance.
American Air Testing uses TEM sampling methods for asbestos abatement clearance as the preferred method. This insures the client of more accurate sampling.
