Reprocessing of N95 masks: our experience from a resource limited setting in India

Rohit, Anusha; Rajasekaran, Shankar; Shenoy, Suchitra; Rai, Sumit; I, Karunasagar; Kumar D, Suresh

OBJECTIVES: Due to the surge in the demand for N95 masks during the current pandemic of Covid-19, and considering the situation in countries grappling with acute shortages in N95 masks, we investigated the possibilities of decontamination and reuse. METHODS: Three N95 masks of different makes (A, B and C), were subjected to 6 decontamination methods, namely UV irradiation, Isopropyl alcohol (IPA) dip, Plasma sterilization ( Sterrad®), Ethylene Oxide (ETO, 3M®), Dry heat sterilization and Moist heat sterilization. The integrity of the N95 masks were assessed by measuring their particle filtering efficiency at particle size range between 0.3 and 0.5 microns. RESULTS: All the masks decontaminated with ETO and plasma sterilization retained over 95% particle filtering efficiency. Masks decontaminated using IPA dip and Autoclaving showed a drop and UV irradiation, showed variations in particle size efficiency degradation, post decontamination. CONCLUSIONS: We recommend plasma sterilization for decontamination of N95 masks in low resource settings. ETO was not recommended due to hazards associated with handling of ethylene oxide, though the filtering efficiency was retained. Since the UV irradiation method showed variations in our results, we recommend that evaluation of UV decontamination for N95 masks needs to be done on a case-to-case basis.