Air conditioning use could be a key indicator in the spread of the deadly coronavirus disease, a Harvard professor warned.
While experts have previously suggested that air conditioning itself may not cause infection, the use of air conditioning suggests more people are confined in small spaces, creating a perfect breeding ground for the virus to spread.
“The [US] states that, in June, are already using a lot of air conditioning because of high temperatures are also the places where there’s been greater increases in spread of COVID-19, suggesting more time indoors as temperatures rise,” Edward Nardell, a professor of medicine, global health, and social medicine at Harvard Medical School (HMS), said, The Harvard Gazette reported Monday.
Nardell, who is also a professor of environmental health, immunology and infectious diseases at the Harvard T.H. Chan School of Public Health, added that the same dynamic is normally seen in cold winters as people flock indoors for warmth.
A significant portion of viral spread has been generally attributed to large water droplets that are expelled when an infected person coughs, talks or sneezes, but there is also evidence that airborne transmission could be causing infection, Nardell said.
Droplets containing coronavirus can be suspended in the air for a short period of time before settling on surfaces, allowing for infection to occur.
Coronavirus and contaminated air
Studies conducted after the SARS outbreak in 2003 suggest that some infections occurred in high-rise buildings as contaminated air rose through the buildings’ airshafts into different apartments. COVID-19 is from the same family as SARS, known as coronaviruses.
In a closed room with the windows closed and the air conditioning on, people tend to rebreathe the same air in the room and from each other, allowing for airborne transmission to occur.
“As people go indoors in hot weather and the rebreathed air fraction goes up, the risk of infection is quite dramatic,” Nardell said, according to the Gazette.
In April, Dr. Maher Balkis, associate staff physician of infectious diseases at Cleveland Clinic Abu Dhabi told Al Arabiya English that air currents caused by air conditioning could also exacerbate this effect.
“It is possible that air currents caused by air conditioning may have allowed droplets in the air to spread further than they otherwise might,” Balkis explained. “These findings are backed up by what we know of other viruses such as influenza, which are not known to spread through air duct systems, rather, they spread through close contact and infected droplets.”