Wearing a mask is currently a very important means of preventing coronavirus pneumonia. At present, two types of masks are recommended: 1. medical surgical masks; 2. N95 masks. As for paper masks and cotton masks, they have no protective properties against coronavirus pneumonia. Medical surgical masks and N95 masks have a preventive and control effect on viruses. Medical surgical masks are divided into three layers, the outer layer is dark blue and the inner layer is white, the outer layer is mainly a waterproof function, while the inner layer is mainly a moisture-absorbing function, so the mask cannot be worn in reverse, and cannot be worn wrongly inside and outside. The middle layer has a role in stopping particles from passing through, mainly for particles around 5μm, the virus is very small in size and cannot be blocked if purely for viruses. Virus transmission is mainly through the respiratory tract, droplet transmission, the virus is attached to the droplet, and the volume of the droplet is generally > 5μm, so the medical surgical mask can prevent virus infection. n95 mask can target particles of 0.3μm size, preventing the transmission of more than 95% of the particles. In N95 masks are divided into biological and anti-haze masks, it is best to choose biological masks. there are also masks with and without breathing valves in N95 masks, if the patient himself is a new type of coronavirus pneumonia, the mask worn cannot be with a breathing valve, because if once the breathing valve is brought, the virus will be transmitted through the breathing valve, others can bring breathing valve N95 masks. Crowded places must apply this mask, before wearing the mask, it is best to wash your hands before wearing the mask. After taking off the mask and folding it inside, put it in a clean plastic bag and keep it inside the hazardous waste bin after use. The mask should not be used after 2-4 hours of application, but in special cases, such as when the mask is tight and there is no clear contact with the patient, it can be reused several times, but at most not more than 5 times and not for more than 2 days. And when using the mask repeatedly, it is recommended that the outer layer of the mask should be disinfected to a certain extent, using alcohol to disinfect it before use. Content source: Dr. You Lai