Development of a new qualitative test for fit testing respirators

A new qualitative fit test was developed using Bitrex (Macfarland Smith Limited) as the test agent. It was validated by running a series of paired qualitative and quantitative fit tests. Quantitative tests were conducted with a small corn oil aerosol, using a condensation nucleus counter as a detector. Qualitative fit tests were run with Bitrex and saccharin, following the established protocol for the saccharin fit test. Four models of National Institute for Occupational Safety and Health--approved replaceable filter respirators were used in the study. All were half mask models equipped with high efficiency filters. In some cases, respirators expected to be the correct size for test subjects were tested. In other cases, respirators expected to be too small or too large for the subjects were tested. Test results were analyzed using fit test method validation criteria recommended in the American National Standards Institute draft standard on fit testing (ANSIZ88.10). The Bitrex and saccharin tests were found to have virtually identical performance. Both met proposed American National Standards Institute requirements for a valid qualitative fit test.