A modified protocol for quantitative fit testing using the PortaCount.

A modified quantitative fit testing method has been developed for testing half masks using the TSI PortaCount respirator fit tester. This approach focuses on shortening the time for each exercise during fit testing; however, the shortened protocol is applied only to the very good-fitting masks. For marginal-fitting masks, the testing is carried out according to the full Occupational Safety and Health Administration (OSHA) respiratory protection standard (29CFR1910.134).(1) The shortened protocol (currently not approved by OSHA) still uses all the exercises required by the OSHA standard but for a shorter time (30 seconds [s] for each exercise instead of the usual 60 s). How good the fit has to be to qualify for a shortened exercise is determined by the statistical analysis of a large data set containing pass and fail fit-test data. The statistical analysis involves calculating the sensitivity and specificity of the pass and failed fit tests on half masks. From this analysis, a multiplication factor (K) to the OSHA pass/fail criterion was developed. For a respirator to undergo the shortened protocol, the fit factor obtained during any exercise must be K times the OSHA pass/fail criterion of 100 for half masks. Hence, this approach is more conservative than fit testing protocols that involve shortened exercises regardless of the fit. Nevertheless, this approach still saves time without compromising the accuracy of the fit test expressed in terms of sensitivity and specificity. For the existing data, 85 percent of the fit tests would have been performed according to the faster test protocol while only 15 percent of the tests would have been tested according to the full-length OSHA test protocol.