Page:NIOSH DM DFM respirator evaluation draft.pdf/55

  NIOSH has concluded there is no reason to believe that the actual quality of respirator programs provided to American workers has improved substantially since Hyatt's 1976 assessment and the 1984 Centaur Associates' report or are substantially better than the 1990 assessments of Revoir. NIOSH has concluded that all respirator workplace studies reported in the 1980s and early 1990s are respirator-performance studies, not respirator program evaluation studies. That is, they evaluate workplace protection factors, not program protection factors.^[1]
  WPF studies frequently are conducted primarily to demonstrate "adequate protection" from a particular make and model respirator. Thus, in effect, WPF studies generally are designed and conducted to measure only respirator performance in the most favorable light possible. This is done to avoid reducing or "biasing" (i.e., systematically distorting) the observed respirator protection resulting from poorly-performed or inadequately-performed respirator program elements that are typically found in actual programs. A major objective in respirator-performance (WPF) studies is to minimize the effects of human errors, even though these errors may typically occur in actual workplace use of respirators. However, it must be recognized that in terms of worker health, WPFs are not the most significant form of the protection factor.
  NIOSH has concluded that respirator wearers in most laboratory and workplace respirator-performance studies are generally given substantially more and better training, fitting, and use observation than is actually received in real-life respirator programs. Thus, many respirator-performance studies are conducted under the effects of ideal respirator Programs that are notably unrealistic compared to the way respirators are utilized in most workplaces, The laboratory protection factors (PFs) and working protection factors (WPFs) reported in any given study and subsequent APF recommendations are representative only of protection levels obtained under conditions similar to those of the study. Therefore NIOSH concludes that the APF conclusions from most laboratory and workplace respirator-performance studies reported to date have questionable external validity concerning WPF results achieved in many real-life respirator programs.
  NIOSH's evaluation has shown that there are considerable differences between the approach to determining APF's used during the 1970s (i.e., Hyatt/LASL) and that used during the 1980s (i.e., Myers, et al.). A summary of NIOSH’s evaluation of these differences is given in Table N of this evaluation. NIOSH has concluded that both APF approaches yield APF's such that while workers are wearing air-purifying, NIOSH-certified respirators in the workplace as part of a state-of-the-art respirator