1. If medical surgical masks are generally used normally, they need to be replaced every 3-4 hours. Do not wear them for a long time and then replace them;
2. If the mask is contaminated while wearing a medical surgical mask, then it needs to be changed immediately. For example, after a sneeze, the mask is all saliva, or it is directly given by sewage. Such similar pollution needs to be replaced immediately;
3. When wearing a medical surgical mask, if you feel difficult to breathe, then you need to change it in time. At this time, the mask has been put on and its life span has reached the end, and more particles have been stored in the mask.
4. If conditions permit, you can wear a surgical mask outside the N95 to reduce the contact of N95 with external dirt;
5. The n95 masks can be reused in areas where there is no contact with infected patients or in areas where there is an epidemic or crowded people, but they also need to be replaced frequently.