Comparison of six respirator fit-test methods with an actual measurement of exposure in a simulated health care environment: Part III--Validation.

This article, the last in a series of three, describes the validation phase of a study conducted to test the correlation of respirator fit factors to the subject's actual exposure using biological sampling. The study consisted of three phases: protocol development, method comparison testing, and validation. Six quantitative fit-test methods were evaluated in the method comparison testing phase. The two fit methods with the highest correlation with the wearers' measured exposure were a corn oil method (R2 = 0.81) and an ambient aerosol method (R2 = 0.78). Because the ambient aerosol method is more commonly used in the workplace, it was selected for further analysis. In this validation phase, the fit factors measured during the ambient aerosol fit-test were used to calculate the exposures to Freon-113 by using the model determined in the method comparison testing phase of the study. The actual Freon-113 exposures were then measured and compared with the predicted exposures. The results verified that the ambient aerosol method fit factors are highly correlated to the total Freon-113 exposure dose and thus that the model had a predictive ability.