Mask study likely spells fit-testing in final TB reg
February 1, 1999 3 minutes read
Mask study likely spells fit-testing in final TB reg
But annual refitting requirement not expected
A recently published government study all but ensures that respirator fit-testing programs will be required in the final version of the federal tuberculosis standard, Hospital Infection Control has been advised.
During the protracted debate on the TB standard proposed by the Occupational Safety and Health Administration, the Association for Professionals in Infection Control and Epidemiology questioned the need for fit testing and objected to the costs associated with such programs — particularly if retesting is required annually. The TB standard is still being finalized after months of hearings and comments. However, a recent study by the National Institute for Occupational Safety and Health (NIOSH), which documented the benefits of fit-testing, very likely means the requirement will be in the final standard, says Julie Sellers, RN, chair of the APIC governmental affairs committee.1
"The findings clearly show in their view the continued necessity to require fit testing," she says. "One of our big issues has been the need for that. I guess we can say that we will inevitably see the continued requirement for fit testing."
A branch of the CDC, NIOSH is the government agency charged with testing and approving respirators. At the height of the TB mask debate in the mid-1990s, it appeared that health care workers might be required to don high-efficiency industrial respirators whenever they treated TB patients. As a result of the ensuing controversy, NIOSH introduced a new classification scheme for respirators and developed criteria for the less expensive and restrictive N95 particulate respirators that many health care workers now use to prevent occupational transmission of tuberculosis. The question of whether N95 respirators needed to be fit-tested in respiratory protection programs to ensure worker protection was raised. According to the NIOSH study, fit testing is a procedure used to evaluate how well a given respirator fits a given person by assessing leakage around the face seal. Fit testing can either be qualitative (i.e., relying on a subjective response of the wearer) or quantitative (i.e., using a measurement of actual leakage).
NIOSH evaluated the performance of 21 N95 respirator models on a 25-person panel. The panel comprised 15 women and 10 men with face lengths and widths similar to the general population. For each test, the person donned the respirator and performed a user seal check (i.e., pressure-tightness test, fit check, or negative/positive pressure check) according to the manufacturer’s instructions. Each person then performed a series of exercises to simulate facial movements during normal use. Quantitative tests also were performed to assess mask leakage.
"The findings in this report indicate that fit testing N95 respirators is essential in programs employing these respirators and can eliminate poorly fitting respirators, ensuring at least the expected level of protection," NIOSH concluded.
Without surrogate fit testing, average exposure for the 25-person panel was reduced to 33% of the ambient level, which is much less protection than expected of the N95 class of respirators. However, when fit-tested first, the panel received substantially greater protection than normally expected (the average exposure was reduced to 4% of the ambient level), the agency reported. Without fit testing, people unknowingly may have poor face seals, resulting in excessive leakage and exposure, NIOSH concluded.
However, while the more elaborate quantitative testing was done to verify findings in the study, it appears that the less rigorous qualitative testing will suffice to ensure worker protection, Sellers noted. Also, the study addressed the efficacy of initial fit testing but did not emphasize any need to refit workers annually.
"So we have the feeling that we will not be doing annual fit testing," Sellers says. "We don’t have to now, and we don’t think we will have to change and begin to when the final rule comes out. But our hope that we wouldn’t have to fit-test at all, I think, is down the drain."
Reference
1. Centers for Disease Control and Prevention. National Institute for Occupational Safety and Health. Laboratory performance evaluation of N95 filtering face piece respirators, 1996. MMWR 1998; 47:1,045-1,049.
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