During the new crown pneumonia epidemic, some people wear N95 masks in their daily homes, and a few people are exposed to less than 1-2 people a day but change their masks regularly, a practice that is completely unnecessary. In a period of mask scarcity, it is necessary to do a good job of protecting yourself while reducing unnecessary waste. It is more important to reduce the number of times you go out, avoid crowded places, wear a mask if necessary, and do your own health monitoring than to change your mask regularly.