workplace protection factors[1] [WPF] measurements made in a representative number of workplace settings and for a representative number of wearers.[2]
Regarding their proposed computational method for APFs, Myers et al. stated:
While no method for calculating assigned protection factors from such (workplace protection factor] data has been established, several methods might be considered. If the distribution of measured workplace protection factors is lognormal, the assigned protection factor could be com. puted from the following relation: . . . If we want to calculate the assigned protection factor for which we would expect 90% of the work- place protection factors to be above, then Z, would be 1.28. If however, we choose 95% instead of 90%, Z, would be 1.64. . . . A more conservative method of determining the assigned protection factor from such data is to compute a one-sided lower tolerance limit above which, for example, we may prodict (sic) with 90% confidence that 90% of the workplace protection factors lie, and equate the assigned protec tion factor to that limit. 69 In the same 1983 Letter to the Editor, Myers et al. of NIOSH gave the definition for another type of protection factor: The "program protection factor" is a measure of the respiratory protection provided to a worker by an established respirator program. . . . In terms of worker health, the program protection factor is the most significant form of the protection factor. It is a measure of the effectiveness of the complete respirator program. The program protection factor is a function of the workplace environment, the activity of the wearer, the fit of the respirator, respirator selection, the respira- tor design, training, maintenance, storage, supervision, program administration and monitoring, and any other variable that affects program effectiveness. If any of these program elements are deficient, the program protection factor will be adversely affected.70 [underlines added] However, none of the protection-factor studies performed by NIOSH or other researchers in the 1980s or early 1990s have evaluated program protection factors.
69Tbid., p. B-26. 70Tbid.,
p. B-26.
- ↑ A measure of the actual protection provided by a respirator in a workplace under the conditions of the workplace by a properly functioning respirator when it is correctly worn and used. A WPF is defined as the ratio of the measured contaminant concentration outside a respirator facepiece (C) to the contaminant concentration inside the facepiece (C). The sampling restrictions placed on C, and C, are that both should be time-weighted average samples taken simultaneously after the respirator has been properly fitted to the wearer and while the respirator is properly worn and used during normal work activities.
- ↑ Myers, W. R., Lenhart, S. W., Campbell, D. and G. Provost: The Forum-Letter to the Editor, Am. Ind. Hyg. Assoc. J. 44(3):B25-26 (1983), p. B-26.
