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Filtration, loading and faceseal leakage characteristics of filtering facepieces.

Willeke K; Chen C; Myojo T; Weber A; Krishnan U; Juozaitis A; Marchioni R; Lehtimaki M
J Aerosol Sci 1992 Jan; 23(Suppl 1):S749-S752
The results of studies on the filtration, loading, and faceseal leakage characteristics of filtering facepieces (disposable respirators) were summarized. An evaluation of eight types of surgical masks used in the United States tested against a corn-oil aerosol at a flow rate of 32 liters per minute (lpm) indicated that 20 to 100% of the particles in the size range of 0.15 to about 1 micron were able to penetrate six of the masks. Even in the case of the best performing mask, 20% of the 0.15 micron sized particles were able to penetrate the mask. This indicated that significant numbers of submicron sized particles would reach the breathing zone of the wearer presenting a potential hazard from aerosolized bloodborne pathogens. The best performing surgical mask was tested against the corn-oil aerosol along with an industrial dust/mist/fume (DMF) mask with or without a simulated faceseal leak. About 5% of the 0.15 micron size particles were able to penetrate the DMF mask with no leaks. Particle penetration increased significantly when 1, 2, or 4 millimeter diameter simulated faceseal leaks were made. The increases were much larger in the case of the DMF mask. This was attributed to the DMF mask having an approximately three times greater pressure drop than the surgical mask. This indicated that the larger a pressure drop across a mask, the more important a leak would become in allowing aerosol particles to penetrate the mask. A new technique for fit testing a disposable respirator was proposed, based on measuring the penetration of a test aerosol through the facemask at flow rates of 10 and 90lpm and the pressure drop. The data could then be used to calculate an equivalent circular faceseal leak that would cause the observed leakage.
NIOSH-Publication; NIOSH-Author; NIOSH-Grant; Respirators; Face-masks; Equipment-reliability; Respiratory-protective-equipment; Aerosol-particles; Laboratory-testing
Environmental Health University of Cincinnati 3223 Eden Avenue Cincinnati, OH 45267-0056
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Journal Article
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Journal of Aerosol Science
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University of Cincinnati, Cincinnati, Ohio
Page last reviewed: September 22, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division