Collection of silica and asbestos aerosols by respirators at steady and cyclic flow.
Department of Environmental Science and Physiology, School of Public Health, Harvard University, Boston, Massachusetts :1-33
Experiments were described which evaluated the predictive ability of tests using a silica (7631869) aerosol under conditions of steady flow for determining respiratory efficiency. Measurements taken of silica penetration at steady flow were reasonably predictive of silica penetration under cyclic flow. Mass penetration of silica under continuous flow conditions was typically less than 0.1 percent. In general, the penetration of silica under conditions of cyclic flow was about one and a half times as great as that measured under steady flow conditions. However, the same was not true for testing with asbestos (1332214) fibers under steady versus cyclic flow. Furthermore, the potential for exhalation valve failure under cyclic flow was also identified. The authors indicate that these results call for a reevaluation of the current NIOSH protocols for evaluating respirator performance. The authors urge the development of a NIOSH testing method for evaluating the life cycle performance of respirator components such as exhalation valves.
NIOSH-Grant; Respirators; Personal-protective-equipment; Silica-dusts; Asbestos-dust; Filter-materials; Electrostatic-filters; Asbestos-fibers; Mineral-dusts; Air-flow; Aerosols
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Department of Environmental Science and Physiology, School of Public Health, Harvard University, Boston, Massachusetts
Harvard University, Boston, Massachusetts