Disinfection efficiency test for contaminated surgical mask by using Ozone generator

BACKGROUND: Ozone (O(3)) is an effective disinfectant agent that leaves no harmful residues. Due to the global health crisis caused by the COVID-19 pandemic, surgical masks are in high demand, with some needing to be reused in certain regions. This study aims to evaluate the effects of O(3) for pathogen disinfection on reused surgical masks in various conditions. METHODS: O(3) generators, a modified PZ 2–4 for Air (2000 mg O(3)/L) and a modified PZ 7 –2HO for Air (500 mg O(3)/L), were used together with 1.063 m(3) (0.68 × 0.68 × 2.3 m) and 0.456 m(3) (0.68 × 0.68 × 1.15 m) acrylic boxes as well as a room-sized 56 m(3) (4 × 4 × 3.5 m) box to provide 3 conditions for the disinfection of masks contaminated with enveloped RNA virus (10(5) FFU/mL), bacteria (10(3) CFU/mL) and fungi (10(2) spores/mL). RESULTS: The virucidal effects were 82.99% and 81.70% after 15 min of treatment with 2000 mg/L O(3) at 1.063 m(3) and 500 mg/L O(3) at 0.456 m(3), respectively. The viral killing effect was increased over time and reached more than 95% after 2 h of incubation in both conditions. By using 2000 mg/L O(3) in a 1.063 m(3) box, the growth of bacteria and fungi was found to be completely inhibited on surgical masks after 30 min and 2 h of treatment, respectively. Using a lower-dose O(3) generator at 500 mg O(3)/L in 0.456 m(3) provided lower efficiency, although the difference was not significant. Using O(3) at 2000 mg O(3)/L or 500 mg O(3)/L in a 56 m(3) room is efficient for the disinfection of all pathogens on the surface of reused surgical masks. CONCLUSIONS: This study provided the conditions for using O(3) (500–2000 mg/L) to reduce pathogens and disinfect contaminated surgical masks, which might be applied to reduce the inappropriate usage of reused surgical masks.