Effects of Long-Duration Wearing of N95 Respirator and Surgical Facemask: A Pilot Study

Abstract

The protection efficacy of facemasks and respirators has been well documented. The change of human nasal functions after wearing N95 respirator and surgical facemask is not known. In a parallel group study, we recruited 87 healthy healthcare workers. Each of the volunteers attended two sessions, and wore N95 respirator in session 1 (S1) and surgical facemask in session 2 (S2) for 3 hours. Mean minimum cross sectional area (mMCA) of the two nasal airways via acoustic rhinometry and nasal resistance via rhinomanometry were measured before and immediately after the mask wearing. Rhinomanometry was repeated every 30 minutes for 1.5 hours after the removal of masks. A questionnaire was distributed to each of the volunteers, during the 3 hours mask wearing period, to report subjective feelings on discomfort level of breathing activity. Among 77 volunteers who completed both the two sessions, the mean nasal resistance immediately increased upon the removal of surgical facemask and N95 respirator. The mean nasal resistance was significantly higher in S1 than S2 at 0.5 hour and 1.5 hours after removal of the masks (p<0.01). There is no statistical difference on mMCA before and after mask wearing in both sessions (p=0.85). The discomfort level was increasing with time while wearing masks, with significantly higher magnitude in S1 (p<0.001). There is an increase of nasal resistance upon removal of N95 respirator and surgical facemask potentially due to nasal physiological changes. N95 respirator caused higher post-wearing nasal resistance than surgical facemask with different recovering routines.