Preventing the Spread of COVID-19 By Circulating Air in Schools and Other Buildings

How COVID-19 Spreads Through the Air

The virus that causes COVID-19 can spread from one person to another in tiny particles of water and virus called aerosols. We make these aerosols when we breathe, and we make more of them when we talk, yell, or sing. Aerosols are different than larger droplets that spread COVID-19. Larger droplets fall to the ground quickly, three to six feet from the person who makes them. Aerosols can stay floating in the air for hours and can travel long distances. Aerosols have less virus in them than the larger droplets, so you have to inhale more aerosols to get sick. Aerosols can build up if the air inside is not circulated the right way.

Airborne transmission of viruses increases during the winter months because people spend more time indoors and it is usually too cold to keep windows open. In winter, the air is drier, especially in heated indoor spaces. Dry air damages the linings of the respiratory tract and can make it easier for virus to get into the respiratory tract. It also means smaller aerosols float in the air for longer periods of time. Therefore, airborne transmission of COVID-19 is expected to be more common during the winter months.

Preventing the Spread of COVID-19 in the Air

Good ventilation in our homes, schools, and businesses can reduce the spread of COVID-19. Learn more about ventilation in different settings through these resources:

• Improving Ventilation in Your Home, CDC
• Ventilation in Buildings, CDC
• Clean Indoor Air Resources, The White House