The COVID-19 pandemic is on the verge of colliding with another public health threat: extreme heat, which kills more people in the US each year than any other weather-related event. Public health officials usually recommend that people without air conditioning head to places like malls and libraries where they can cool off, but that’s not an option for a lot of people sheltering at home.

The problem could soon begin to affect India

The problem could soon begin to affect India, where temperatures begin to climb in April and have reached as high as 45 degrees Celsius (113 degrees Fahrenheit). India’s 1.3 billion residents have been ordered to stay indoors until April 14th to stop the spread of disease, and only about 5 percent of the population has air conditioning.

Heat-related illness can begin with mild symptoms like a headache and muscle cramps, and they can progress to confusion, dizziness, vomiting, and losing consciousness. Once the body reaches a point where it can no longer cool itself down by sweating, heat stroke can lead to organ failure and eventually death. Those most at risk are often the poor and elderly, groups that are similarly hard-hit by the novel coronavirus. Heat-related deaths can be prevented by checking in on people who might be isolated indoors and providing public places for them to get out and cool down. But those strategies contradict efforts to stop the spread of COVID-19, which mostly focus on keeping people apart.

“We’re in between a rock and a hard place if it were to become a heatwave during the time when we’re enacting physical distancing measures,” says David Eisenman, a professor at the University of California Los Angeles’ department of community health sciences.

“We’re in between a rock and a hard place”

In developing countries, the migration to cities from rural areas has posed new problems when it comes to preventing deaths from heat. Traditionally built homes in less densely packed areas often included designs that naturally kept the structure cool, like inner courtyards and windows aligned to allow prevailing winds to pass through. But poorer newcomers to cities have packed into informal settlements where homes may be little more than brick or metal walls with a corrugated metal roof. “That’s literally an oven,” says Kurt Shickman, executive director of the Global Cool Cities Alliance, which partners with governments to plan more heat-resilient cities. It’s estimated that 40 percent of the world’s urban expansion takes place in slums, and more than two-thirds of the world’s population is expected to live in cities by 2050, according to the United Nations Development Programme.

“The problem is way worse in the developing world, but we shouldn’t take that and say that we’re out of the woods here [in the US],” Shickman says. The US sees upward of 600 heat-related deaths each year. Heat waves, which are becoming more frequent and more intense because of climate change, took a heavy toll in Europe last year, too, killing almost 1,500 in France last June and July.

“[Extreme heat] is even more of a pressing issue with the pandemic than it was beforehand, and this need for staying at home is only bringing out issues that already existed,” says Sonal Jessel, a policy and advocacy coordinator for the Harlem-based nonprofit WE ACT for Environmental Justice. Even though New York City has just stepped into spring, Jessel is already scrambling to figure out strategies to keep people safe in case hotter temperatures arrive earlier this year.

Temperatures can be several degrees hotter in cities

Temperatures can be several degrees hotter in cities like New York compared to surrounding areas, because all the asphalt and concrete absorb and trap heat. It can be even hotter in industrial neighborhoods with fewer trees and parks, which means some communities are more vulnerable than others. Almost half of all people who lost their lives to heat in New York City between 2000 and 2012 were African American, although they’re just under 25 percent of the city’s population.

“Now that we’re all instructed globally not to gather in close proximity, it’s going to really call for creativity and quick pivoting among public health systems around the world,” says Kim Knowlton, a senior scientist at the National Resources Defense Council, who has worked with Jessel’s organization in New York and other groups in India to prevent heat-related illness and death. She and other public health experts are beginning to put their heads together to figure out how they may need to tackle two crises — coming heat waves and the ongoing pandemic — in tandem. But they don’t have answers just yet.

Cities might have to figure out how to create publicly accessible places where people can cool down while also maintaining enough physical space between each other to prevent the spread of COVID-19, Eisenman at UCLA says. “It just seems like a really hard thing to pull off,” he says.

More needs to be done to help people cool down at home

If beating the heat by going to a public place is out of the question, then more needs to be done to help people cool down at home, says Jessel. That means getting air conditioners into more homes, and helping people pay their utility bills so that they don’t need to choose between running their air conditioning and paying for other necessities. With lots of people losing their jobs during the pandemic, making air conditioning affordable is even more pressing. Jessel’s organization is advocating for more funding for the Low Income Home Energy Assistance Program, a federally funded program that provides assistance with home energy bills. Beyond that, Jessel and other advocates are pushing for ways to retrofit homes to keep them cooler. Installing better insulation, painting roofs white to reflect the sun, and planting rooftop gardens can keep homes and buildings cool.

Temperatures in parts of California, where there’s a state-wide shelter-in-place order, are going to rise above 80 degrees Fahrenheit (about 27 degrees Celsius) next week. While Eisenman doesn’t think those numbers will begin to pose a threat just yet, he warns that the first really hot days of the season can be particularly dangerous because people are still adjusting to the change in temperatures. And while California and New York are current hotspots for COVID-19 in the US, he worries that other states with fewer coronavirus cases now but hotter climates, like Arizona, might see their number of cases peak closer to the start of summer. That potential scenario could be deadly, which is why Eisenman and others are encouraging groups to take early measures to address the combination of threats — before the case counts and temperatures start to rise.