1. PCM cannot visualize fibers less than 5.0 microns in length or 0.25 micron in width. In our experience, this makes up the majority of asbestos released during abatement activity.
2. PCM cannot distinguish asbestos from non-asbestos fibers.
3. TEM can visualize fibers less than 0.5 microns in length and 0.01 micron in width.
4. TEM can differentiate asbestos from non-asbestos fibers using morphology, selected area electron diffraction (SAED), and energy dispersive x-ray analysis (EDXA).
5. TEM is technically superior and more defensible in a court of law.
6. “EPA strongly recommends that abatement site air clearance collected from public & commercial buildings be analyzed by TEM at NVLAP accredited labs.” (EPA Federal Register Vol. 59, No. 23, Thursday, February 3, 1994)
7. TEM is now widely available and a cost effective methodology for assuring the safest conditions possible for ambient & final air clearance monitoring.

The following micrographs are from the same final clearance air filter. The TEM micrographs are examples of structures not counted by PCM.

PCM Scope Mag. 400X F/cc=0.0043 F/mm˛=14.6 TEM Scope Mag. 15,500X S/cc = 0.1120 S/mm˛=379.9 TEM Scope Mag. 15,500X S/cc = 0.1120 S/mm˛=379.9