The Fallacy of PCM Clearance Air Sampling*
Angelo Garcia, III, Future Environment Designs
Under the Environmental Protection Agency’s (EPA’s) Asbestos Hazard Emergency Response Act (AHERA) clearance sampling is required for projects less than 160 square feet or 260 linear feet down to a minor fiber release episode. This clearance sampling is typically done utilizing the National Institute of Occupational Safety and Health’s (NIOSH) 7400 methodology for asbestos air sampling that utilizes phase contrast microscopy. However, this methodology was not developed for the purpose of asbestos clearance sampling where you would have relatively low counts of asbestos fibers on the filter. This methodology was developed for atmospheres where it was expected to have high concentrations of asbestos fibers on the filter. This presentation will discuss several problems with utilizing the NIOSH 7400 method for clearance sampling and changes that should be made for clearance sampling to mean the work area is actually safe for workers and the public to reenter.