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

Abstract

Quantitative fit tests (QNFT) have been assumed to be predictive of the protection respirators would provide to a wearer in the workplace. Workplace studies have consistently found no correlation between quantitative fit factors and workplace protection factors. This article is the first in a series of three describing a study designed to compare the fit factors from six QNFT methods against the actual dose of 1,1,2 trichloro-1,2,2 trifluoroethane (Freon-113) received under the same laboratory conditions. Five preliminary studies conducted to develop the protocol to assess the respirator wearer's dose through end-exhaled air analysis are described in this article: (1) chamber characterization, (2) end-exhaled air sampling, (3) skin absorption testing, (4) pharmacokinetic modeling, and (5) subject characterization. It was established that the concentration of corn oil aerosol and Freon-113 could be generated simultaneously in the chamber. It was ascertained that the optimum time to sample the exhaled breath was 30 minutes after the subject exited the chamber. It was also found that in a chamber concentration of 500 ppm, without any respiratory exposure, Freon-113 was still present in the end-exhaled air. This was attributed to skin absorption. The end-exhaled air of subjects exposed to 0.5, 3, 5, 25, 50, and 100 ppm (30 minute time-weighted average) of Freon-113 was evaluated at 30 minutes postexposure. This characterization was then used to predict the actual dose of Freon-113 received during the method comparison and validation testing to be described in subsequent articles.