Masks should not be worn for too long

There are many blood vessels in the nasal cavity, and there are many spongy vascular networks, which make blood circulation in the nasal cavity strong. The nasal cavity and the entire surface of the respiratory tract are covered with many mucous membranes, with microvessels beneath them. When cold air was drawn into the nose and entered the lungs through a tortuous tube, the temperature of the air was close to body temperature. This physiological function of the human body can be enhanced through exercise, thereby improving the person's cold resistance. If you wear a mask all day, the nasal cavity and the mucous membranes of the entire respiratory tract are not exercised, and you will catch a cold easily if you get a little cold. Of course, wearing a mask is necessary to walk in the wild to protect against wind and sand and cold or air pollution, but it should not be too long.