From the human physiological structure, because the human nasal mucosal blood circulation is very strong, the nasal cavity is very tortuous, nose hair from a filter "barrier." When the air inhales the nostrils, the air flow in the meandering channel to form a vortex, so that the air flow into the nasal cavity to get warm. Some people have shown that air is heated to 28.8 ° C when the cold air at minus 7 ° C is sucked into the lungs through the nasal cavity, which is very close to the temperature of the human body. If you wear a long mask, will make the nasal mucosa become fragile, lost the original physiological function of the nasal cavity, it can not wear long mask. Masks can only be worn in a special environment, for example, where people do not have air. Of course, walking in the wild, in order to resist sand and cold, or in an air pollution environment, is the need to wear a mask, but the time should not be too long. In addition, in the influenza epidemic season, to the existence of a large number of pathogens in public places, but also wear a mask. Wearing a mask is only one way to prevent respiratory infections, the most important thing is to maintain a good living habits.