Does Prolonged Use of N95 Masks Affect Nasal Mucociliary Clearance? A Single Group Pre-Post Study.

Objective: It has been shown that prolonged use of face masks results in physiological changes in the nasal cavity. The objective of this study was to examine the effect of prolonged use of face masks on nasal mucociliary clearance (NMC).

Methods: A single group pre-post study was conducted to determine the effects of prolonged use of N95 face mask (≥4 hours) on the NMC rates in health care workers. Saccharin transit time (STT) was used to measure the NMC. STT before and after using an N95 mask for at least 4 hours was measured for all participants in controlled conditions of temperature and humidity.

Results: Forty-eight volunteers (20 female and 28 male) completed the study after the enrollment of 57 volunteers. The mean STT before mask use was 580.27 ± 193.93 seconds (95% CI; 523.95-636.58 seconds) and after mask use was 667.47 ± 237.42 seconds (95% CI; 598.53-736.42 seconds). There was significant prolongation of the NMC after prolonged use of N95 mask on performing the paired -test ( = .002). The mean prolongation was 87.20 ± 184.97 seconds with an actual effect size of 0.40. Ambient temperature and humidity were not significantly different at the two test instances.

Conclusion: Use of the N95 face masks for 4 hours results in prolongation of the nasal mucociliary clearance as measured by STT. Susceptibility to any respiratory infection may be increased following doffing of the personal protective equipment, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) itself.