Harvard professor believes AC may be contributing to spike in COVID-19 cases down south

CAMBRIDGE, Mass. — Many states down south are seeing huge spikes in the number of new COVID-19 cases. An infectious disease expert at Harvard University believes he may know why. He blames it, partially, on air conditioning.

Dr. Edward Nardell is a professor at Harvard Medical School and Harvard School of Public Health. He said the heat is forcing people inside, where the coronavirus can linger for hours.

“It’s exactly the opposite of what was happening here in January, February and March when we were indoors and people in Florida were saying, ‘what COVID?’” Dr. Nardell said.

Nardell said another factor in the spread of COVID-19 is that most air condition systems in public spaces often recirculate their air. It's essentially stale air.

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"Most air condition systems bring in very little outside air, so the rebreathed air fraction goes up. The amount of air I exhale, that you inhale," he said.

Dr. Nardell, though, said using air conditioning in your home that is recirculated isn’t a problem since there’s a low risk of transmission among family members. Instead, it’s those crowded indoor areas with poor ventilation that pose the biggest risk because air conditioning units push the same infected air around the room.

“We say particles land within actually three feet. For socially distancing we’ve said six feet, and that all depends on still air. In moving air, particles can go further,” Dr. Nardell said.

He added that one of the best ways to stop the spread of COVID-19 through air conditioning is through ultraviolet air disinfectant, which basically kills germs in the air. Portable room air cleaners can also be used.

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