The wearing and use of the mask should be based on the product instructions, strictly according to the protocol, for medical surgical masks, specific wearing methods are as follows: 1, nasal clip side facing up, dark side facing out (or fold facing down); 2, pull the fold up and down, so that the mask covers the mouth, nose and jaw; 3, the fingertips of both hands along the metal strip of the nasal bridge, from the middle to both sides, slowly pressed inward until tight to the nasal bridge; 4, appropriate adjustment of the mask, the Make the perimeter of the mask fully fit the face. There are many types of masks, but the use of time limited, to be replaced regularly, preferably every 2-4 hours to replace. If the mask is wet or dirty with secretions and the protection performance is reduced, it is recommended to replace it immediately.