The replacement time of Kn90 mask is not fixed. It needs to be replaced after wearing it for 2 ~ 4 hours, and it also depends on whether there is a timeout in the mask. When the mask is used for a long time, it is wet by the breathing gas, resulting in the decline of anti-virus ability. In this way, it needs to be replaced even before the time. How often to replace the Kn90 mask? Kn90 mask is a kind of dust mask, which is suitable for filtering non oily particles. The filtering effect on oily particles above 0.185 microns is greater than 90%. This mask is not like a disposable mask, which can be thrown away once, but it also has a service life.
In principle, the N90 mask is disposable. It needs to be replaced after wearing it for 2 ~ 4 hours, and it also needs to be determined according to whether there is timeout inside the mask. Therefore, the replacement time is not completely fixed. Usually, after a long time of use, the mask will be wet by the breathing gas, which will lead to the decline of anti-virus ability. At this time, it needs to be replaced in time.
So don't think that Kn90 masks have a fixed replacement time. We should replace this disposable mask regularly. Especially after we feel that the mask is wet, we should try our best to reduce going out when the air pollution is serious or infectious diseases are serious, or go out after changing the mask.