Validation of a Respirator Performance Model

Abstract

This article presents results of an experimental validation of a model for predicting the performance of half-mask respirators. The model predicts respirator performance for protection against aerosols. It uses as input the measured fit factor, an estimated work rate, the exposure particle size distribution, and known performance characteristics for the type and brand of filter used. The validation tests involved the measurement of respirator performance, using human subjects, under simulated use conditions with known fit, work rate, particle size distribution, and filter performance. Comparison is made between measured and predicted performance for two conditions each of fit, particle size, and work rate. Fit factors ranged from 5 to 231, test aerosol mass median aerodynamic diameters from 0.6 to 1.3 μm, and work rates from 0 to 50 W. Based on tests conducted here, the predictive model does a reasonable job of predicting penetration under simulated use conditions where fit factor, size distribution, work rate, and filter efficiency are known. It is able to account for 58 percent of variability in measured penetration under the conditions of these tests. The model adequately accounts for the effect of fit (as determined by quantitative fit test), work rate (breathing pattern), and particle size distribution, and shows no bias with the magnitude of these parameters. Given the intrinsic variability of respirator performance measurements, the model is useful for predicting the effect of these variables on respirator performance.