AILSA CHANG, HOST:
Researchers say there is increasing evidence that in crowded indoor spaces, the coronavirus is spreading through the air and causing super-spreading events. NPR's Pien Huang explains what they think is happening and how researchers say you can protect yourself.
PIEN HUANG, BYLINE: Six months ago, 53 people caught coronavirus at a now-notorious choir practice in Washington state. It raised a big red flag for scientists like Jose-Luis Jimenez at University of Colorado Boulder who study how the coronavirus spreads.
JOSE-LUIS JIMENEZ: People who were 50 feet from the index case got infected.
HUANG: Before everybody got sick at this choir practice, most scientists thought the coronavirus was really only spreading when people came within six feet of each other. Since then, it's become clearer and clearer that in certain situations, especially crowded rooms with stale air, clouds of coronavirus breathed out by infected people can accumulate in the air...
LINSEY MARR: Wafted by air currents and travel around the room and be inhaled by other people.
HUANG: That's Linsey Marr, an engineering professor at Virginia Tech. She says these clouds of coronavirus floating through the air seem to be playing a key role in super-spreading events where the coronavirus spreads to a lot of people at once - at weddings and nursing homes, prisons and dorms. Jimenez at UC Boulder says the unifying thread seems to be enclosed spaces with a lot of people and not a lot of air. So they're situations he stays away from.
JIMENEZ: We have to avoid if it's crowded, if people cannot keep the distance, if it's a long time, if there is low ventilation, if people are not wearing masks or if people are talking or especially singing or yelling or also breathing hard.
HUANG: That is a lot of things to try to remember to avoid. What you can do instead, Jimenez says, is spend time outside.
JIMENEZ: I think if you are outdoors with distance and with a mask that is well-fit, I would say it's extremely difficult to get the disease that way.
HUANG: He says you can think of these coronavirus clouds as plumes of smoke. Researchers think you have to get a concentrated whiff to get sick. So if you're outside, surrounded by fresh air, any virus clouds will disperse pretty quickly. And if you have to go indoors to a shared public space like the post office or the supermarket, Seema Lakdawala, a flu researcher at the University of Pittsburgh, says, keep your distance from others and keep it moving.
SEEMA LAKDAWALA: You're not in one space for any prolonged period of time. And so even if there are fine aerosols that are released by somebody who is infected, they're getting diluted out as these people move and air currents pick them up.
HUANG: And if you are in charge of people gathering indoors at your house or in your store or in a classroom, Marr at Virginia Tech says, try to make the indoors more like the outdoors and get that stale air moving.
MARR: If you can sweep that out and replace it with outdoor air, that can help reduce the problem of buildup of viruses in indoor air.
HUANG: You can open a door or put a fan in the window to exchange the air. Researchers say that in most settings, these potential virus clouds can be dispersed with a light breeze and some fresh, clean air.
Pien Huang, NPR News. Transcript provided by NPR, Copyright NPR.
