The Centers for Disease Control and Prevention updated its website to say that the coronavirus can sometimes spread farther than six feet through tiny, airborne particles. This is the second time this information went out; last month, the agency accidentally published (and then removed) a draft version of the guidelines.

Scientists have stressed for months that people can catch COVID-19 by inhaling tiny, virus-laden particles that float for minutes or hours in the air. Those particles can build up in poorly ventilated, indoor spaces. A few specific cases, like a chorus practice in Washington state, contributed to that picture of how the virus spreads.

The CDC said in a statement that it continues to believe that spending time in close contact with a sick person is the most common way people catch COVID-19. Situations like the chorus practice, though, show that it can occasionally spread other ways as well. “In these instances, transmission occurred in poorly ventilated and enclosed spaces that often involved activities that caused heavier breathing, like singing or exercise. Such environments and activities may contribute to the buildup of virus-carrying particles,” the agency wrote.

The revised CDC guidelines now say that masks can protect against airborne spread of COVID-19. The website also stresses the importance of ventilation in indoor spaces. Being outside, where particles will be quickly diluted out, can reduce the risk of getting sick.

Formal recognition of airborne spread supports recommendations from public health experts, who’ve long stressed the importance of ventilation and spending time outdoors. Many schools and businesses turn to the CDC to make decisions, and codification on the agency website may help encourage groups to make ventilation a priority.

https://www.theverge.com/2020/10/5/21502755/cdc-guidelines-airborne-covid-spread-ventilation