Performance of dust respirators with facial seal leaks: II. Predictive model.
A performance model for half-mask and single-use respirators is presented. It represents a possible alternative to field measurements of respirator performance. Experimental data on filter and leak performance given in Part I were used to develop a model that allows one to predict 1) the overall respirator penetration as a function of particle size for any work rate and 2) overall total mass penetration for any work rate and exposure aerosol-size distribution for a known respirator filter and facial seal leak condition. A simplified method based on general regression equations is presented that allows one to estimate these quantities based on QNFT (quantitative fit testing) measurements and a knowledge of the exposure aerosol-size distribution. Example calculations are given for a situation in which QNFT gives a fit factor of 50 for a half-mask with dust, fume and mist filter cartridges, but predicted protection factors for various use conditions range from 20 to 81 depending on exposure particle-size distribution and work rate of the wearer.
Hinds
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WC
University of California Southern Occupational Health Center, UCLA School of Public Health 90024.
Bellin
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D000336:Aerosols; D004391:Dust / Q000032:analysis*; D004868:Equipment Failure; D005374:Filtration / Q000379:methods; D006801:Humans; D008397:Masks / Q000592:standards*; D010316:Particle Size; D011237:Predictive Value of Tests; D011482:Protective Devices / Q000592:standards*; D012134:Respiratory Protective Devices / Q000592:standards*
D000336:Aerosols; D004391:Dust