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Penetration of airborne microorganisms through a surgical mask and a dust/mist respirator.
Willeke K; Qian Y; Donnelly J; Grinshpun S; Ulevicius V
Am Ind Hyg Assoc J 1996 Apr; 57(4):348-355
A surgical mask was compared with a dust/mist respirator for aerosol penetration of bacteria of different aspect ratio (length to width), size and shape. Bacteria used included Streptococcus-salivarius, Bacillus-megatherium, Pseudomonas-fluorescens, and Bacillus- alcalophilus. Inert spherical test particles composed of corn-oil were also used. The mask or respirator was sealed to a mannequin, and exposed to an aerosol in a test chamber. A pump was used to produce airflows of 16, 32, 50 and 80 liters/minute through the mask or respirator to simulate breathing. An aerodynamic size spectrometer was used to measure aerosol concentrations. The collection efficiency of nonspherical bacteria was always higher than that of spherical test particles. Penetration of bacteria through the filter of either the mask or the respirator decreased with increasing aspect ratio for a given aerodynamic diameter. P- fluorescens, similar in size and shape to Mycobacterium- tuberculosis, had a penetration of about 50 to 60% of that of spherical test particles of the same aerodynamic diameter. Both the surgical mask and the dust/mist respirator showed the same dependence on aspect ratio, in spite of differences in efficiency.
NIOSH-Publication; NIOSH-Grant; Respirators; Respiratory-protective-equipment; Aerosol-particles; Microorganisms; Infection-control; Author Keywords: aerodynamic size spectrometer; bacterial penetration; Mycobacterium tuberculosis; respirator; efficiency; microorganism
Environmental Health University of Cincinnati 3223 Eden Avenue Cincinnati, OH 45267-0056
American Industrial Hygiene Association Journal
University of Cincinnati, Cincinnati, Ohio
Page last reviewed: October 9, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division