A Scalable Method of Applying Heat and Humidity for Decontamination of N95 Respirators During the COVID-19 Crisis

Loïc Anderegg; Cole Meisenhelder; Chiu Oan Ngooi; Lei Liao; Wang Xiao; Steven Chu; Yi Cui; John M Doyle

This research studied the effect of five cycles of heating to 85 o C for 30 min with a relative humidity of 60-85% on a selection of N95 FFRs. We found that for all of the N95 models we investigated there was no significant difference in filtration efficacy between the test groups of masks and the untreated control masks. For the mask models that were able to pass a fit test prior to cycling (3M 1860 and 3M 8210 Plus), there was no measurable degradation of fit after each decontamination cycle, nor relative to the control group masks. As such, we found that the heating protocol described in this article is compatible with 3M models 1860 and 8210 Plus FFRs. The Chen Heng V9501 KN95 and HKYQ N95 showed no degradation in the filtration tests, but their fit factor value was in the 4-45 and 5-28 ranges respectively (where 100 is normally considered passing). Further work is still required to ensure viral inactivation of SARS-CoV-2 on FFRs.