The duration of effectiveness of medical masks is usually 6-8 hours. Medical protective masks have the protective properties of both surgical masks and particulate protection masks, and are often used in hospitals to filter airborne particles and block the spread of droplets, blood, body fluids and secretions, and also belong to Class II medical device products. Wearing medical protective masks for more than 8 hours will need to be replaced, if not replaced in time, it will affect the airtightness of the mask and reduce the filtration effect. If you do not need to wear the mask during its effectiveness time, fold it and keep it in a self-sealing bag, and fold the side that touches the nose and mouth inward. It is not recommended to take off the mask and stuff it directly into the pocket or other places, which is easy to cause secondary pollution of the medical mask. In addition, it should be noted that, in addition to medical protective masks, any type of mask has its own statute of limitations and must be replaced regularly, such as ordinary disposable medical masks, more than recommended 2-4 hours to replace once, if the mask is contaminated, need to be replaced immediately.