Asbestos Fiber Collection by NIOSH-Approved Respirators.
Evans-JS; Brosseau-LM; Ellenbecker-MJ
Department of Environmental Science and Physiology, Harvard School of Public Health, Boston, Massachusetts 1989 Feb:5 pages
The first phase of this project involved assessing the size specific collection efficiencies of ten manufacturer's dust/mist respirator filters using monodisperse latex spheres. The second phase involved the evaluation of the overall collection efficiencies of three manufacturer's respirators using silica (14808607) and asbestos (1332214) aerosols under steady and cyclic flow conditions. The final phase involved an examination of the relationship between these empirical results and the predictions of both physically based and semi empirical models. Using latex spheres a high degree of efficiency, typically greater than 99.5 percent, was demonstrated by the dust/mist respirator filters for collecting particles with aerodynamic diameters greater than 1 micrometer. A minimum collection efficiency was noted of about 90 percent for particles with aerodynamic diameters of 0.1 micrometers. When the dust/mist respirators were challenged with a silica test aerosol, the overall mass collection efficiencies centered on 99.5 percent at steady flow conditions. Under cyclic flow conditions the silica penetration was about 50 percent greater than under steady flow. In tests with amosite (12172735) asbestos, an overall efficiency of 99.9 to 99.99 percent was achieved at steady flow. Under cyclic flow conditions, the corresponding figure ranged from 98 to 99.5 percent. The authors recommended that NIOSH test its respirators as much as possible under conditions similar to those in actual use at the job site.
NIOSH-Grant; Respirators; Personal-protective-equipment; Aerosol-particles; Asbestos-fibers; Mineral-dusts; Silica-dusts
Environmental Sci & Physiology Harvard School of Public Hlth 665 Huntington Avenue Boston, MA 02115
14808-60-7; 1332-21-4; 12172-73-5
Final Grant Report
NTIS Accession No.
Department of Environmental Science and Physiology, Harvard School of Public Health, Boston, Massachusetts
Harvard University, Boston, Massachusetts