About KN95 masks:
KN95 mask can isolate smaller particles, and fit tighter to the face, it is not easy to leak air from the periphery, and the filtration efficiency of particulate matter can reach 95% under standard conditions.
The KN95 mask is not a disposable mask. In this special case (resource shortage), it can be reused. But there are conditions:
1. When KN95 receives contamination such as saliva, blood, tears and other body fluids, it must be replaced
2. The user obviously feels that the breathing resistance is greater than before and must be replaced
3. Masks are damaged and must be replaced
4. It is recommended to replace it after using it 4 times.