As electret technology can drastically improve the filtration efficiency of disposable procedure masks and portable air purifiers, it is widely used to prevent the airborne transmission of SARS-CoV-2. Furthermore, alcohol disinfectants are now widely used in offices, hospitals, and homes to prevent contact infection; hence, there is a concern that alcohol exposure may inactivate electret. In this study, 5 types of high-efficiency particulate air filter (HEPA) air purifiers - of which, one was made of fiberglass HEPA filter - 14 types of cubical masks, and 11 types of pleated masks available to Japanese citizens were subjected to discharge according to the alcohol exposure protocol based on ISO (International Organization for Standardization) 16890, and changes in filtration efficiency and pressure drop were measured before and after the discharge. The results revealed that 17 (68%) of the 25 masks exhibited a significant decrease in filtration efficiency; this decrease due to discharge depended on the filter material. However, masks of polypropylene, polyethylene, and poly-vinylidene-difluoride composite fiber materials exhibited no significant decrease in filtration efficiency. In addition, 4 (80%) of the 5 HEPA filters showed a 40-64% decrease in filtration efficiency, while no decrease in filtration efficiency was observed for the fiberglass HEPA filter. Our survey (n = 500 Japanese adults, including 30 healthcare professionals) revealed that approximately 90% of the general public was unaware that the performance of masks and air purifiers could be degraded by direct spraying of alcohol - for disinfection purposes - or vapor exposure. Furthermore, 36% of the surveyed healthcare professionals indicated that they had sprayed alcohol directly on their masks. Therefore, based on the results of this experiment, we examined effective consumer warnings that could be utilized on the product labels and in the instructions. The results showed that it would be more effective to detail the extent and duration of the adverse effects of disregarding the precautions.

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