Disposable medical masks and surgical masks are limited to use, and the cumulative use shall not exceed 8 hours. Occupational exposure personnel shall not use medical protective masks for more than 4 hours and shall not use them repeatedly. When the mask is contaminated by the blood, body fluids or nasal secretions of the infected person, and the respiratory resistance of the mask increases, it should be replaced in time when it is in close contact with the infected person. If the mask becomes wet or contaminated by secretions, it must be replaced immediately. For healthy ordinary people, if there are no symptoms such as fever, catarrh, runny nose, sneezing and stuffy nose. The same mask should be worn by one person, stored correctly and reused no more than 5 times. Use and store masks correctly to prevent them from being deformed.