ABSTRACT
Passive samplers in the workplace are commonly exposed to relatively high concentrations of contaminants for time periods ranging up to eight hours. Some commercial passive samplers have been "validated" for such use, which according to the applicable National Institute for Occupational Safety and Health (NIOSH) criteria 1 requires that in the laboratory they show a standard error (S.E.) of 25 percent or less at one, two, and five times some standard concentration (usually the Threshold Limit Value, TLV) and a S.E. of 35 percent or less when tested at one-half the standard concentration. The difficulty in applying the NIOSH validation to the long-term sampling of environmental contaminants is that the concentrations we wish to measure may be several factors of ten below the concentrations found in industrial exposure, and the sampling periods may be one week or longer, i.e., more than twenty times the sampling period in the original validation. Generally the NIOSH validation cannot be used, and the passive sampler must be revalidated for environmental monitoring.
