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Does Your A/C Spread COVID? We Asked an Expert

Is Your air conditioning a superspreader? 
FACT CHECKED BY Emilia Paluszek

Does an air-conditioned environment raise the risk of getting COVID-19? Reports from the beginning of the pandemic suggested it was a major cause of concern. "All of the data we are seeing from bars and from indoor locations, a choir practice that led to 60 people getting infected, I think there's plenty of evidence that aerosols are really a major source of spread," said Ashish Jha, M.D. (currently the White House Coronavirus Response Coordinator) back in July 2020. Here's what experts are saying today about the possible link between air conditioning and COVID-19. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


How Is COVID-19 Spread?

Waiter coughing into elbow while serving customers in a restaurant.

COVID-19 is commonly spread through airborne particles and droplets, both indoors and outdoors—but outdoors is less risky, experts say. "Being outside provides more air flow so the virus is more easily diluted," says Daphne Darmawan, pediatrician at UC Davis Children's Hospital.


How Important Is Ventilation?

woman coughing into elbow while lying down on sofa in the living room.

Ventilation is incredibly important in preventing the spread of COVID-19, experts say. "The science is airtight," says Joseph Allen, director of the Healthy Buildings program at Harvard University's T.H. Chan School of Public Health. "The evidence is overwhelming… In the first year of the pandemic, it felt like we were the only ones talking about ventilation, and it was falling on deaf ears. But there are definitely, without a doubt, many companies that have taken airborne spread seriously. It's no longer just a handful of people."


Theoretically, How Could A/C Spread COVID?

Woman using an air conditioner

While not all air conditioners work in the same way, "a lot of the air is recirculated," says Linsey Marr, the Charles P. Lunsford professor of civil and environmental engineering at Virginia Tech and an expert in aerosol science. "And when you recirculate that air, that means that the virus is still sticking around in that building, rather than being replaced by more outdoor air, which presumably is virus-free."


Could Turning Off the A/C Makes Things Worse?

woman checking air conditioner at home

"If shutting off air-conditioning means that ventilation and filtration functions will be disabled, it is quite possible that risk of infection will increase, but if there is no ventilation or filtration, circulation of air in a space may contribute to risk," says William Bahnfleth, PhD, PE, director of the Indoor Environment Center in the Department of Architectural Engineering at Pennsylvania State University and the chairman of the ASHRAE Epidemic Task Force.


Your A/C Is Likely Not Spreading COVID

Air conditioner inside the room with woman operating remote controller

The general consensus amongst scientists and virus experts is that being indoors with other people is what causes the spread of COVID-19, not air conditioning. "It is not the air conditioner that is doing anything particularly," says Edward Nardell, professor of environmental health and immunology and infectious diseases at Harvard Medical School. "It is the fact that you are indoors, you are not socially distancing and you are rebreathing the air that people have just exhaled."


How to Stay Safe Out There


Follow the public health fundamentals and help end this pandemic, no matter where you live—get vaccinated or boosted ASAP; if you live in an area with low vaccination rates, wear an N95 face mask, don't travel, social distance, avoid large crowds, don't go indoors with people you're not sheltering with (especially in bars), practice good hand hygiene, and to protect your life and the lives of others, don't visit any of these 35 Places You're Most Likely to Catch COVID.

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan