If N95 masks are used by frontline healthcare workers during an epidemic, they are usually worn continuously for no more than 6 hours. Ordinary people are not continuously wearing N95 masks, usually replaced once a day. N95 mask specific use period is not clearly defined, and different environments, the time worn is also different.N95 masks have an important role in the protection of the epidemic, wearing N95 masks can effectively prevent the spread of the disease, spread. During the epidemic if the frontline medical personnel, a N95 mask usually can not be worn continuously for more than 6 hours, and in order to prevent infection requires a one-time use. During the epidemic, ordinary people wearing N95 masks, the maximum time to wear a day. If the mask is contaminated with secretions and sputum, it should be replaced in a timely manner. As the virus is more contagious during the epidemic, healthcare workers under virus exposure must wear masks above the N95 standard in accordance with the standard. It is recommended that no matter what kind of masks need to be used in strict accordance with the use of norms, so as not to cause infection.