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Performance of N95 respirators: filtration efficiency for airborne microbial and inert particles.

Authors
Qian-Y; Willeke-K; Grinshpun-SA; Donnelly-J; Coffey-CC
Source
Am Ind Hyg Assoc J 1998 Feb; 59(2):128-132
NIOSHTIC No.
20023155
Abstract
In 1995 the National Institute for Occupational Safety and Health issued new regulations for nonpowered particulate respirators (42 CFR Part 84). A new filter certification system also was created. Among the new particulate respirators that have entered the market, the N95 respirator is the most commonly used in industrial and health care environments. The filtration efficiencies of unloaded N95 particulate respirators have been compared with those of dust/mist (DM) and dust/fume/mist (DFM) respirators certified under the former regulations (30 CFR Part 11). Through laboratory tests with NaCl certification aerosols and measurements with particle-size spectrometers, N95 respirators were found to have higher filtration efficiencies than DM and DFM respirators and noncertified surgical masks. N95 respirators made by different companies were found to have different filtration efficiencies for the most penetrating particle size (0.1 to 0.3 micron), but all were at least 95% efficient at that size for NaCl particles. Above the most penetrating particle size the filtration efficiency increases with size; it reaches approximately 99.5% or higher at about 0.75 micron. Tests with bacteria of size and shape similar to Mycobacterium tuberculosis also showed filtration efficiencies of 99.5% or higher. Experimental data were used to calculate the aerosol mass concentrations inside the respirator when worn in representative work environments. The penetrated mass fractions, in the absence of face leakage, ranged from 0.02% for large particle distributions to 1.8% for submicrometer-size welding fumes. Thus, N95 respirators provide excellent protection against airborne particles when there is a good face seal.
Keywords
Performance-capability; Filtration; Microbiology; Microorganisms; Respirators; Dust-measurement; Spectrographic-analysis; Particulate-dust; Infectious-diseases; Infection-control; Respiratory-protective-equipment; Respiratory-protection; Personal-protective-equipment; Personal-protection; Author Keywords: efficiency; filter; microorganism; Mycobacterium tuberculosis; respirator
Contact
Department of Environmental Health, P.O. Box 670056, University of Cincinnati, Cincinnati, OH 45267-0056
CODEN
AIHAAP
Publication Date
19980201
Document Type
Journal Article
Email Address
klaus.willeke@uc.edu
Funding Amount
746102
Funding Type
Grant
Fiscal Year
1998
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003244
Issue of Publication
2
ISSN
0002-8894
NIOSH Division
DRDS
Priority Area
Respirator Research
Source Name
American Industrial Hygiene Association Journal
State
OH
Performing Organization
University of Cincinnati, Cincinnati, Ohio
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