Wearing a mask protects susceptible people. Masks are a sanitary and epidemiological product. Wearing a mask filters the air that enters the mouth and nose to effectively block harmful gases, odors, droplets, viruses, and other substances. Masks have a certain filtering effect on the air entering the lungs. New crown pneumonia, influenza and other respiratory infectious diseases, can spread the virus through the respiratory droplets, correctly wearing a mask can effectively block droplets from the respiratory tract into the human body, can cut off the transmission pathway, so as to achieve the purpose of preventing viral infections, for the susceptible population has a certain protective effect. It should be noted that the outer layer of the mask may accumulate a lot of dust, bacteria and other pollutants in the outside air, while the inner layer blocks the exhaled bacteria, saliva, etc. Therefore, the mask needs to be worn correctly, avoiding alternating between the two sides, so as not to affect the protective effect of the mask. Wearing a mask can provide effective protection for susceptible people. In addition to go out and wear a mask, during the epidemic of respiratory infectious diseases, should also try to avoid going to densely populated places, and should pay attention to personal hygiene habits, hand washing, etc., to do a good job of protection. [Tip] This article refers to “new coronary pneumonia, new coronary virus pneumonia”, etc., has been December 26, 2022, the National Health Commission issued a notice to change the name to “new coronary virus infection”.