Why extreme heat is so alarming for the fight against Covid-19

By Umair Irfan

A heat wave is baking much of the United States this week, with some of the highest temperatures forecasted in Southwestern states battling some of the most troubling coronavirus outbreaks in the country.

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However, the combination of extreme heat and a fast-spreading virus in the Sun Belt is now creating a new set of problems that could undermine efforts to control Covid-19. From hampering surge capacity plans for hospitals to increasing people’s likelihood of getting exposed to the virus while sheltering indoors from the heat, heat can make things harder. And temperatures are poised to rise even higher in the southwest in the future due to factors like the urban heat island effect and climate change.

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When temperatures get searingly hot, people spend more time in enclosed spaces, which presents the greatest opportunity for infection if the virus is present. “I’m actually really worried about indoor transmission,” said Davidson Hamer, a professor of global health and medicine at Boston University. “It’s so hot in the Southwest US that people are not outside. They’re being driven inside, so then you have all the issues of aerosol transmission and recycled air, a lot of which honestly we don’t fully understand yet.”

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Another issue during heat waves is that air pollution tends to get worse on hot days. Pollutants like ozone form more readily in high temperatures, which in turn can exacerbate breathing problems. That’s particularly troubling for a respiratory infection like Covid-19 that has shown a link between more severe illness and air pollution. In poorly sealed buildings, that outdoor pollution can become indoor air pollution, often leaving the poorest residents of a city little respite.

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