Is the fit of N95 facial masks effected by disinfection? A study of heat and UV disinfection methods using the OSHA protocol fit test.

Amy DPhil Price; Yi Cui; Lei Liao; Wang Xiao; Xuanze Yu; Haotian Wang; Mervin Zhao; Qiqi Wang; Steven Chu; Larry F Chu

Previous work by Heimbuch et al 13 reports testing 15 models but 3 models failed to fit the model head and couldn't be tested. After 10 cycles of UVGI all tested models indicated a significantly lower peak force for treated straps for at least one condition tested compared to controls and doffing. Nevertheless, Heimbuch et al 13 report that UVGI does not significantly degrade fit factor testing after 10 treatment cycles 13 . They report that of six FFR models tested, after 20 treatment cycles, respirators by Kimberly Clark PFR and U.S. Safety AD4N95 failed two of the three fit testing conditions assessed. The untestable mask models in the Heimbuch et al report 13 were certified by NIOSH and cleared by the FDA. Evaluation of UVGI by Bergman et al 1 . report fit factor was not significantly degraded by treatment of UVGI)=15-min @ 254nm, however they did not test the straps and only one side of the N95 faced the lamp. The 3M company 7 tested N95 masks UVGI 30min @ 254nm (15-min per side) and they report elasticity loss, a strong burnt odor and nose foam compression on some models. Straps are an unescapable component of respiratory mask fit.