For the epidemic that will appear in China from the end of 2019 to the beginning of 2020, ordinary dust masks cannot play an effective protective role. Because ordinary dust masks as well as cotton gauze masks, cloth masks, sponge masks, activated carbon masks, etc., these masks are basically made of cotton, gauze, sponge or canvas, the material is not fine enough, the gap is larger, and cannot effectively block the new crown virus, so it is not recommended. For protection, medical surgical masks, medical care masks and industrial particle protection masks N95 and KN95 are preferred. If you can’t buy the above masks, you can use KN90 or medical disposable masks instead. For individuals, the best way is to avoid contact with the source of infection and to avoid being infected by going out less.