Climate Change Could Be Good News for Viruses Like COVID

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MONDAY, April 29, 2024 — Climate change — and closed windows — could be aiding the spread of airborne viruses like the one that causes COVID-19, a new study suggests.

Increased levels of carbon dioxide in the atmosphere and in indoor spaces appear to be a major factor in prolonging the life of COVID variants present in tiny airborne droplets, researchers report.

“We knew SARS-CoV-2, like other viruses, spreads through the air we breathe. But this study represents a huge breakthrough in our understanding of exactly how and why that happens, and crucially, what can be done to stop it,” said lead researcher Allen Haddrell, a senior research associate in aerosol science at the University of Bristol School of Chemistry in the U.K.

In lab studies, researchers found that rising carbon dioxide concentrations in the air can increase the length of time that airborne viruses remain infectious.

Normal outdoor air has a CO2 level of 400 parts per million (ppm), researchers said.

Increasing CO2 concentrations to just 800 ppm increased the survival of airborne viruses, according to results published April 25 in the journal Nature Communications.

And when indoor air reaches a CO2 concentration of 3,000 ppm — similar to that of a crowded room — around 10 times as much virus remained infectious after 40 minutes, researchers found.

“This relationship sheds important light on why super-spreader events may occur under certain conditions,” Haddrell said in a university news release.

Viruses lose their infectiousness because of the lower acidity of exhaled droplets, Haddrell said.

But CO2 behaves as an acid when interacting with the droplets, allowing the viruses to live longer while airborne.

“It shows that opening a window may be more powerful than originally thought, especially in crowded and poorly ventilated rooms, as fresh air will have a lower concentration of CO2, causing the virus to become inactivated much faster,” Haddrell said.

The results also show how climate change goals seeking to limit CO2 levels in the Earth’s atmosphere could also help dent the spread of airborne viruses, Haddrell added.

Recent climate science has projected the concentration of CO2 in the atmosphere to reach more than 700 ppm by the end of the century, researchers noted.

“These findings therefore have broader implications not only in our understanding of the transmission of respiratory viruses, but how changes in our environment may exacerbate the likelihood of future pandemics,” Haddrell said.

“Data from our study suggests that rising levels of CO2 in the atmosphere may coincide with an increase in the transmissibility of other respiratory viruses by extending how long they remain infectious in the air,” Haddrell concluded.

More information

The World Health Organization has more on COVID-19 transmission.

SOURCE: University of Bristol, news release, April 25, 2024

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