Virus infected patients in coughing, breathing, sneezing in the formation of droplets, viruses with droplets sprayed outside the body, in the process of spraying out of the body gradually lose moisture, this time will be mixed with proteins and pathogens to form a nucleus, the nucleus contains viruses, will become a droplet nucleus containing viruses. Some droplet nuclei are relatively small in size and may be suspended in the air to form aerosols. The virus depends on the droplet nucleus to form an aerosol and spread, and droplet nuclei in aerosol form may travel long distances, up to several meters or more. The current clear routes of transmission of novel coronaviruses are droplet transmission and contact transmission. Although aerosol transmission has not been identified as a definitive route of transmission at this time, there is still a need for concern and prevention of this mode of transmission, and the risk of this mode of transmission cannot be denied. Places such as crowded elevators, in poorly ventilated restrooms, and in closed offices may cause aerosol transmission. Content source: Dr. Yurai