Preliminary Results on How Longer Facial Hair Lengths May Interfere With N95 Respirator Efficacy: A Brief Report.

Abstract

Background: The use of the N95 respirator outside work environments calls for a deeper understanding of the factors that interfere with its fitting, thus effectiveness. Here we determined how beard length influences N95 effectiveness. This research will improve guidance for individuals that use N95s in public spaces but cannot shave due to personal reasons.

Methods: Bearded males (N = 28) participated in this study. Participants' beard length was measured at the chin, mid jawline, and corner of the mouth, and a respirator fit tester was used to conduct a quantitative fit test. Participants then shaved and re-took the test. Fisher's exact test was conducted to determine the association between bearded (BEA) and clean-shaven (CLE) conditions and test passing rate. A mixed effects model was conducted with participants as a random factor to determine the differences in fit factor (FF) scores between conditions. Finally, a regression analysis was completed to determine if there was a linear relationship between the FF response and beard length at the three locations.

Findings: No statistically significant difference in passing rate (p-value = .79) and mean FF scores between BEA and CLE (F_1,54 = 0.75, p-value = .39) was found. Although the regression analysis failed to detect a statistically significant relationship between the FF and beard length at the chin, mid jawline, and corner of the mouth (p-values = .07, .27, and .11, respectively), the results showed a decrease in FF scores when beard length increased.

Conclusion/application to practice: Individuals who cannot shave completely should be encouraged to keep their beard as short as possible since beard length negatively impacts N95 effectiveness.