LB736 Wearing N95 masks does not disrupt the facial skin microbiome

The COVID-19 pandemic has elevated concern about mask-related skin problems like so-called ‘maskne’ which is likely rooted in the skin microbiome. We therefore determined if wearing an N95 mask affects the skin microbiome in a 3-day controlled study. On Day 1, subjects (n=10) followed their normal office routine without a mask. On Days 2 and 3, subjects wore an N95 mask (3M Model 8210) from morning to late afternoon (6 hours). The same mask was used both days. Microbiome diversity and composition (16S rRNA amplicon sequencing, V1-V3), stratum corneum (SC) barrier function (TEWL), SC hydration, skin redness and follicular porphyrins were measured on the cheek (masked site) and forehead (control site) each morning and afternoon. At the end of the study, a sample of each mask was collected for microbiome analysis. Mask wearing showed no significant effect on alpha (Shannon) or beta (Brays-Curtis) microbiome diversity. Mask wearing had no significant effect on Cutibacterium acnes relative abundance. Mask wearing corresponded to a small increase in the genus Staphylococcus relative abundance on Day 2 (p=0.03) but not Day 3. There was no significant effect of mask wearing on SC hydration or follicular porphyrins. TEWL and skin redness were elevated (p<0.05) on Day 2 and Day 3 on the masked cheek but not the unmasked forehead; values returned to baseline from Day 2 PM to Day 3 AM. Finally, the mask microbiome reflected that of the subject’s skin; the relative abundance of C. acnes on the subject’s mask correlated with that on the subject’s cheek skin (r2=0.46, p<0.001). In conclusion, wearing an N95 mask for 6 hours per day on two consecutive days under routine office work conditions did not significantly affect the diversity or composition of the skin microbiome and produced only transient changes in visible skin redness and barrier function. Longer term studies with different types of masks under non-office conditions are needed to further understand the influence of mask wearing on the skin microbiome.