Particulate Air Purifying Respirator Filter Efficiency: Separation of Aerosol Charge and Relative Humidity Effects.
NIOSH 1989 Dec:33 pages
A series of tests was performed on commercial respirator filters to separate the effects of aerosol charge and relative humidity (RH) preconditioning on performance. Four conditions were tested: as received filters with the challenge aerosol conditioned with a radiation source to neutralize the aerosol; as received filters challenged with a charged aerosol; filters pretreated for 42 days at 38 degrees-C and 85% RH with a neutralized aerosol; and RH pretreated filters with a charged aerosol. Filters of the dust, fume and mist; paint, lacquer and enamel mists; and dust and mist types were tested. Both electrostatic and electret type filter media were tested. In each of the tests at least four aerosol particle sizes were used. All filters were tested at a flow rate of 85 liters per minute. A drop in filter efficiency was noted of approximately 10 to 20% between the charged and neutralized aerosol, with the neutralized aerosol giving the higher penetration. The drop in efficiency due to RH pretreatment was 2 to 6%. The authors conclude that the charge on the aerosol is important to a greater degree than the degradation of the filter media from RH pretreatment.
NIOSH-Author; Personal-protective-equipment; Respiratory-equipment; Filter-materials; Equipment-reliability; Respirators; Testing-equipment; Materials-testing;
NTIS Accession No.
Control Technology and Personal Protective Equipment; Research Tools and Approaches; Respirator Research; Respirators;
Division of Safety Research, NIOSH, Department of Health and Human Services, Morgantown, West Virginia, 33 pages, 13 references