EXPERIENCE IN THE USE OF THE NIOSH DIFFUSIVE SAMPLER EVALUATION PROTOCOL

Diffusive sampler operation may be affected by a large number of facto rs. Interactions between the factors may also be important. A protocol for determining sampler performance has been developed by the Nationa l Institute for Occupational Safety and Health (NIOSH) that addresses sampler precision and accuracy when these factors vary within the rang es normally encountered in the field. However, it is costly, time-cons uming, a nd often unnecessary to apply all of the tests to each sample r for every possible chemical hazard. A sampler shown to sample a spec ific vapor accurately may be assumed to require fewer tests to assure equal performance with related chemicals. The criteria used to define the reduced tests depends somewhat on sam pier design, a nd the justif ication for applying the criteria must depend on information gained fr om validating a large selection of related chemicals using the full pr otocol. Thus, the full protocol remains the standard of reference for the lower validation level. Based on these considerations a ''bilevel validation'' approach was developed for the SKC 575 series diffusive s ampler. Application of the bilevel approach to the NIOSH protocol is d escribed, and the results are related to the full NIOSH protocol and a lso to a European validation protocol. The European protocol recognize s the validity of reduced rests for homologue validation. The conclusi ons are that (1) it is feasible to validate a sampler for a large numb er of organic Vapors using the NIOSH protocol a nd that this number ca n be substantially increased by use of a bilevel approach, saving time and resources, and (2) samplers validated to either the NIOSH or Euro pean protocol should be accepted as meeting the requirements of the ot her.