The life-span of N95 masks and some of its theories

I think that N95 masks mainly decrease with the use time, an average of 1.2% for 8 hours a day, and it will decrease to 90% after 33-40 hours, which is equivalent to the level of N90. Working 8 hours a day can be calculated for at least 5 days, which is consistent with CDC’s recommendation of limited repeated use of 5 times, and the protective effect is acceptable.

If it is stored in an airtight dry container after static disinfection when it is not worn for a long time, the performance degradation can be ignored.

Regular use can be stored in a general environment to avoid high humidity environments.

Try to ensure that the shape of the mask is not damaged, wear and store carefully.

The service life of N95 masks with breathing valves may be more than doubled.

The efficiency reduction is mainly concentrated at the sub-nanometer level. The filtration efficiency of this level is directly related to the static charge of the filter material. The filtration efficiency of the micron level mainly comes from physical barrier.

There is a real shortage. In theory, it is used for 8 hours a day for 54 days in a daily environment, that is, after 430 hours of use, the PFE is reduced to 30%, which is only equivalent to foreign surgical masks.