Air is not the same as aerosol. Aerosol is a kind of colloidal dispersion system formed by solid or liquid small masses dispersed and suspended in a gas medium, sometimes called gas dispersion system. The dispersed phase is a solid or liquid particle, and the dispersion medium is a gas. Liquid aerosol is usually called fog, solid aerosol is called fog smoke. And air is a mixture of gases in the atmosphere, generally colorless and odorless, gaseous, the composition is mainly nitrogen, oxygen, carbon dioxide, as well as rare gases and other substances. Air composition is generally not fixed, and its ratio changes as altitude and air pressure change. Air and aerosols are two different substances, but aerosols are widely present in the air and move with air circulation. Sometimes aerosols as small particles suspended in the air have the potential to cause disease. Aerosols are generally easy to form, but it is not easy to infect people. Ordinary medical masks can block viruses contained in aerosols. In unventilated environments, such as closed rooms or elevators, aerosols containing viruses may remain in the air for a longer period of time. Therefore, it is recommended that people wear masks when they go out and open windows regularly when they live at home to keep the air circulating and avoid inhalation of aerosols that can lead to infection. Content source: Dr. You Lai