Date of Graduation

1996

Document Type

Dissertation/Thesis

Abstract

For a number of years, it was assumed that the protection measured during a laboratory fit test was indicative of the protection provided by the respirator during actual use in the workplace. Beginning in the early 1980's, workplace protection factor studies were conducted to validate this assumption. These studies indicated that quantitative fit test results did not correlate with actual workplace protection factors. A fit test that indicates the degree of exposure is especially important when Mycobacterium tuberculosis (TB) exposures are involved. This study tested the correlation of fit factors to the subject's actual exposure using biological sampling. Six quantitative fit test methods were tested: continuous high flow deep probe (CHD), continuous low flow flush probe (CLF), controlled negative pressure (CNP), 30 minute condensation nuclei counter with ambient aerosols (CNC30), standard duration condensation nuclei counter with ambient aerosols (CNC), and exhalation valve discharge (EVD). Eleven subjects were fit tested while doing simulated health-care movements in a chamber containing 500 parts per million 1,1,2 trichloro-1,2,2 trifluoroethane (Freon{dollar}\\sp\\circler{dollar} 113) and corn oil or ambient aerosol. The fit factor obtained with each of the methods was compared to the Freon{dollar}\\sp\\circler{dollar} 113 protection factor as determined from analysis of the subject's exhaled breath. The fit factors provided by the CNC and CHD methods correlated the best with the Freon{dollar}\\sp\\circler{dollar} 113 protection factors. A model was developed to predict the Freon{dollar}\\sp\\circler{dollar} 113 protection factors based on the fit factors provided by the CNC test. The model was: Log of the Freon{dollar}\\sp\\circler{dollar} 113 protection factor = {dollar}-{dollar}0.488 + 0.925* (the log of the fit factor from the standard duration condensation nuclei counter test). This model was then validated on the same eleven subjects by comparing the predicted Freon{dollar}\\sp\\circler{dollar} 113 protection factors calculated from the model to the Freon{dollar}\\sp\\circler{dollar} 113 protection factors derived from sampling the subjects' exhaled breath. The validation results verified that the CNC test was moderately correlated to the Freon{dollar}\\sp\\circler{dollar} 113 protection factor. Therefore, the CNC does provide health-care workers an indication of the protection their respirators will provide against TB. Also, this test can be used to answer other questions regarding the efficacy of respirators.

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