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Filter efficiency degradation in N95 respirators caused by sodium chloride aerosol.

Bergman-MS; Moyer-ES
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :61
The National Institute for Occupational Safety and Health (NIOSH) investigated effects of periodically loading small masses of sodium chloride (NaCl) aerosol on the filtration efficiency of N95 filtering facepiece respirators. NIOSH certifies that N95 respirators must provide at least 95% filtration efficiency as per the 42 CFR 84 test criteria. N95 respirators are specified for protection against solid and water-based particulates (i.e., nonoil aerosols). New N95 respirators from three different manufacturers were loaded with 5 + / - 1 mg NaCl aerosol 1 day a week, over a period of 17 weeks. Aerosol loading and penetration measurements were performed using the TSI 8130 Filter Tester. Respirators were stored uncovered on an office desktop outside of the laboratory. To investigate environmental and temporal effects of filters being stored without NaCl exposure, control respirators were stored on the desk for various lengths of time before being initiated into weekly testing. For all manufacturers' respirators, the controls showed similar initial penetrations on their day of initiation to those of the study samples on day 1. As the controls were tested weekly, they showed similar degradation rates to those of the study samples. Results show that some of the manufacturers' models had penetrations of greater than 5% when exposed to intermittent NaCl aerosol loads. This data suggests that service time recommendations should account for efficiency degradation with intermittent, low-level loading of NaCl aerosol. It is concluded that periodic loading of small masses of NaCl aerosol onto N95 respirators has a significant degrading effect on filter efficiency. Furthermore, it is noted that effects of storage time and storage atmosphere in this study are much less significant.
Respirators; Respiratory-equipment; Face-masks; Air-purifying-respirators; Personal-protective-equipment; Performance-capability; Testing-equipment; Equipment-reliability; Sodium-compounds; Chlorides; Aerosols; Aerosol-particles; Filters; Filtration; Laboratory-testing; Environmental-factors; Materials-storage
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American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia