Evaluation of the Benefit of the User Seal Check on N95 Filtering Facepiece Respirator Fit

Abstract

The objective of this study was to better understand the benefit of the user seal check step for respirator test subjects in the N95 filtering facepiece respirator donning process. To qualify for the study, subjects were required to pass a standard quantitative fit test on at least one of the three N95 filtering facepiece respirator models: 3M 1860 (cup), 3M 1870 (flat-fold), and Kimberly Clark PFR95-270 (duckbill). Eleven subjects were enrolled and performed a series of abbreviated, quantitative fit tests where they were randomly asked either to perform or not perform a user seal check with 20 different respirator samples of each model. The experimental design included 3 respirator models × 10 subjects × 2 treatment levels with 10 replications. Geometric mean (GM) fit factors and percentages of times a fit factor ≥ 100 was achieved for a donning were compared for each subject with and without the user seal check across all models and for each model. Higher GM fit factors and smaller geometric standard deviations across all models were achieved for 10 of the 11 subjects when performing a user seal check compared with not performing a user seal check. Geometric mean fit factors of 148, 184, and 156, compared with 126, 187, and 115, respectively, were obtained for the 3M 1860, 3M 1870, and Kimberly Clark PFR95-270 models when the user seal check was performed vs. not performed. Differences in the GM fit factors for the 3M 1860 and Kimberly Clark PFR95-270 models were statistically significant (p < 0.05) when performing a user seal check vs. not performing a user seal check. These data suggest that there may be some benefit to performing the user seal check for at least some models during the filtering facepiece respirator donning process for workers who have previously passed a fit test for those respirator models. Additional research is needed with larger groups of subjects and respirator models/types.

Evaluation of the user seal check on gross leakage detection of 3 different designs of N95 filtering facepiece respirators

“…Therefore, the current results may underestimate the passing rate of QNFT. 24 Second, Asian participants' weight (reported here) and facial anthropometries (eg, face length, face width; not reported here) were significantly different from that of non-Asian people, which hence affects the passing rate of QNFT. Such differences might reduce the generalizability of the results but increase the specificity of that to Asian populations.…”

“…Unlike well-controlled internal hospital settings in other regions, these environmental differences may limit the current results in that they are less relevant to other settings but are highly situation-specific results for many hospitals located in subtropical climate regions. Further studies are recommended to replicate the works from Myers et al 23 and Viscusi et al, 24 which examined the effectiveness of the user seal check on improving N95 respirator donning among Asian wearers. Another study may investigate how the change of body weight and facial anthropometries of Asian health care workers contributes to leakage of N95 respirators.…”

“…10,20,21 Previous experimental studies on U.S. subjects suggested that the user seal check improved the donning of N95 respirators. 23,24 Although the scale of these studies was not large enough (N = 11 and N = 64), 23,24 the rigor of the experimental design and the use of repeated measurements increased the credibility of the results. Some guidelines suggest that no further fit testing is needed for a given respirator if subjective leakage is detected by a user seal check.…”

Fitting Characteristics of N95 Filtering-Facepiece Respirators Used Widely in China

“…For the testing without training (D1F, D2F), all 50 subjects donned the FFR and conducted fit test after reading the respirator manufacturer's instructions themselves, including performing and passing a use-seal check [21]. For the testing after training, the researchers instructed the same 50 subjects to don and doff a respirator and to conduct the use-seal check.…”

Respiratory protection policies and practices among the health care workforce exposed to influenza in New York State: Evaluating emergency preparedness for the next pandemic

“…A seal check is required by the OSHA standard (the facility was made aware of this), and research has demonstrated that a seal check is beneficial to HCWs who have been previously fit tested. 7 Without a proper seal between the user's face and the respirator, inhaled air may bypass the respirator's filter, putting the user at risk for exposure. 8 Influenza vaccination has been repeatedly demonstrated to be an effective means in protecting patient health, but inoculation rates in the United States have remained low.…”