A Nonrigorous and Incorrect Evaluation of the Fast Fit Test.

To the Editor:

In the article published in CHEST (June 2022), Regli et al present data for health care personnel wearing a duckbill N95 filtering facepiece respirator, the BSN Medical ProShield, with a standard quantitative fit-testing method and then, approximately 1 year later, with a quantitative fast fit-test protocol. Among the 19 individuals tested at each time point, 42% passed the standard protocol and 74% the fast fit protocol. The authors state that employees should have received better fits 1 year later, being more experienced wearers, which is what happened. Surprisingly, Regli et al conclude that the higher pass rates are attributable to a flaw in the fast fit-test protocol. There is no evidence to support this conclusion.

The study validating the fast fit-test protocol followed a national consensus standard, which requires testing the new and control protocols in random order, one immediately following the other, without removing or changing the fit. The new protocol must be tested on a wide range of respirator models with subjects having a wide range of face sizes. We were contracted by the Project Enhancement Corporation to review the validation data as part of the Occupational Safety and Health Administration (OSHA) vetting process and concluded that the method met the performance criteria. OSHA accepted the new protocol despite a few negative comments in the regulatory docket.

Regli et al did not follow the consensus standard requirements for comparing fit test protocols, and their study does not offer a methodologically robust critique. Overall, they showed the two methods were concordant for 74% of participants (nine passed and five failed both tests). The five participants that failed the standard fit-test and passed the fast fit-test approximately 1 year later may have gained more experience with respirators (though hopefully were not wearing the tested respirator in the meantime). These results are consistent with research that observed individuals with prior respirator experience were more likely to don their respirator correctly. The pass rates observed by Regli et al are better than those of Low et al, who found a pass rate of only 34% with the same BSN N95 filtering facepiece respirator.

This research letter communicates the observations of fit-testing protocols for one respirator model at one health care organization and extends those observations to an unsound conclusion. Implementation of effective respiratory protection programs in health care organizations is of critical importance to occupational health and should be advanced through rigorous inquiry.