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Filtration and face-fit characteristics of respirators.
Willeke-K; Myojo-T; Chen-C; Weber-A; Marchioni-R
Proceedings of the Occupational Health Seminar, Seoul, Korea, August 12, 1992 1992:31-35
The filtration and face fit characteristics of filtering (disposable) respirators were discussed. The general rationale for using respirators in workplace environments was discussed. Filtration tests performed on surgical masks, selected as an example of an disposable respirator, have shown that they can be penetrated by submicrometer sized aerosols, which in operating rooms and other clinical settings could potentially expose the wearer to aerosolized bloodborne pathogens. Face fit tests have shown that disposable respirators under normal conditions show greater leakage of submicrometer size particles than industrial dust/mist/fume (DMF) respirators. When leaks are added, the DMF respirators they show a much larger increase in leakage rate than the surgical mask. This was attributed to there being a much larger pressure drop across the DMF respirator. Fit tests have shown that when leaks are placed in the respirators, particles larger than 1 micrometer in size penetrate more readily through DMF respirators than surgical masks despite the fact that disposable masks have a lower filtration quality. This observation has led to the authors suggesting that when fit testing disposable respirators, the penetration of the test aerosol be evaluated at high and low flow rates. By computing a fit index (FI) defined as the difference between penetration measured at high and low flow rates, for a respirator with and without a leak, a quantity the ratio of the FI with a leak to an FI measured without a leak that can be directly related to the fit characteristics of any respirator is obtained.
NIOSH-Grant; Respirators; Respiratory-protective-equipment; Dust-masks; Industrial-hygiene; Laboratory-testing; Equipment-reliability;
Environmental Health, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267-0056
Respirator Research; Respirators
Proceedings of the Occupational Health Seminar, Seoul, Korea, August 12, 1992
University of Cincinnati, Cincinnati, Ohio
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division