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

## TL;DR

This study explores how beard length affects the effectiveness of N95 respirators and finds that longer beards may reduce their performance.

## Contribution

This paper provides preliminary evidence that beard length may interfere with N95 respirator fit and effectiveness.

## Key findings

- No significant difference in passing rates was found between bearded and clean-shaven conditions.
- Beard length showed a trend of decreasing fit factor scores, though not statistically significant.
- Participants are advised to keep beards as short as possible to maintain respirator effectiveness.

## Abstract

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.

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.

No statistically significant difference in passing rate (p-value = .79) and mean FF scores between BEA and CLE (F1,54 = 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.

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