A mask includes a body. An edge portion of the body is provided with a sealed member fitted and adapted to a human face, and a space allowing gas or liquid to be filled therein is provided in the sealed member. During wearing and using, since the sealed member filled with gas or liquid is used as a contact structure for the mask contacting with the human face, the sealed member filled with gas or liquid is elastic and can be deformed when contacting with the human face. Thus, in actual wearing, such a gas-filled or liquid-filled structure can enable the sealed member to self-adapt to different facial features due to the deformation, which ensures the airtightness of the mask, thereby ensuring filtering effectiveness of the mask. A method of improving mask airtightness applied to the mask is further provided according to the present application.
