How long should N95 masks be used

N95 mask is not disposable masks and can be used repeatedly. Regarding the duration of use, according to a test of N95 masks, the attenuation of the filtering performance of N95 mask after 4 hours of use is very limited and can be ignored. If N95 mask is used for more than 100 hours, its filtration efficiency (for 0.3 micron particles) is still above 90%, which is higher than disposable medical masks, so there is no need to worry too much about the durability of filtration efficiency.

Research has found that the filtration efficiency remains above 95% and the breathing resistance does not change much after medical N95 mask is used for 2 days. After used for 3 days, the filtration efficiency dropped to 94.7%. After 6 days of use, the filtration efficiency drops to 90%. Therefore, wearing N95 masks for 3 days can theoretically meet international standards.

If N95-level mask is steamed, washed, and sterilized with ultraviolet light, its filtration efficiency will quickly drop from 95% to less than 60%, which is similar to ordinary gauze masks and cotton masks. In addition, disinfecting the mask with alcohol will destroy the filtering effect. Therefore, it is generally not recommended to reuse N95 masks.