Ordinary medical masks can play a certain protective role in the prevention of pneumonia. Viral pneumonia is mainly spread by respiratory droplet transmission. Since viruses exist in droplets, and the filtration efficiency of ordinary medical masks is greater than 30%, they can block most of the viruses that stick to the droplets and prevent them from entering the respiratory tract, and can be used in the prevention of new coronavirus pneumonia. It is recommended to wear single-use medical masks in open and ventilated places in areas of high epidemic prevalence; medical surgical masks or particulate protection masks when entering crowded or confined public places; and particulate protection masks or medical protection masks without exhalation valves when visiting hospitals with suspected symptoms.