How extreme heat can be damaging to your long-term health

As climate change leads to a warmer planet with hotter days, experts say everything from chronic diseases to respiratory health to infectious diseases will be affected.

Illustration by Alex Cochran for Yahoo News; Photos: Chuchart Duangdaw, MirageC, Miralex via Getty Images
Illustration by Alex Cochran for Yahoo News; photos: Chuchart Duangdaw/Getty Images, Mirage/Getty Images, Miralex/Getty Images

Heat can be deadly, killing more people every year than other weather hazards. But as hotter days become our new normal — or, as some climate scientists say, our “new abnormal” — the ill effects of higher temperatures on our bodies can persist a lot longer than you might think.

The World Health Organization says that climate change is “the single biggest health threat facing humanity.” And while that may sound like hyperbole, experts say it’s really not so far-fetched.

“There are really direct relationships between climate and health, and what we’re seeing in many cases we could call ‘climate-exacerbated disease,’” Dr. Christopher Tedeschi, director of emergency preparedness for emergency medicine at Columbia University, told Yahoo News.

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Why extreme heat is bad for your health right now

Stop sign with desert landscape in background that reads: Stop, extreme heat danger. Walking after 10 AM not recommended.
A sign at Death Valley National Park on Monday, where the temperature was 120°F and climbing. (Francine Orr/Los Angeles Times via Getty Images)

Walking outside on an oppressively hot day, it’s easy to see how excessive heat can do immediate harm. Heatstroke and heat exhaustion may be among the first conditions that come to mind. Heatstroke, which occurs when the body loses its ability to cool down and control its temperature, can cause permanent disability and even death, with body temperatures possibly rising to 106°F or higher in under 15 minutes. Heat exhaustion, which includes symptoms like dizziness, nausea and headache, can lead to heatstroke unless treated immediately.

But extreme heat can also be damaging in less obvious ways, and may have a major impact on chronic diseases.

“Heat puts stress on your body, and when your body is stressed it has a hard time dealing with other things like cardiac conditions or respiratory conditions,” Tedeschi said. “When you look at, for instance, emergency department visits during times of extreme heat, more people present with heart attacks, more people present with strokes, and that is frankly just a reflection of the stress on the body.”

Higher temperatures also often lead to poorer air quality, with extreme heat and stagnant air increasing the amount of ozone and particle pollution. And after you've endured a scorcher, all that heat can harm your sleep too, with even mild heat exposure keeping body temperatures up, affecting sleep stages and hindering the ability to fall and stay asleep.

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How high temperatures hurt your health in the long term

Two park rangers in uniform pose for picture near a visitor center sign against a desert landscape while a third ranger holds a cellphone pointed at them next to a digital sign reading: 132F 55C
National Park Service rangers next to an unofficial heat reading at Furnace Creek Visitor Center in Death Valley National Park on Sunday. (Ronda Churchill/AFP)

“On an individual level, I think it’s about that heat stress over a good amount of time,” Tedeschi said. “If you are continually exposed to extreme heat or hot temperatures that your body can’t deal with, I think that frankly puts you at risk for things that your body might be able to fend off otherwise.”

There are also more downstream effects. Wildfire smoke — which has become an all-too-familiar problem in much of the U.S. as fires continue to smolder in Canada and California — has harmful health consequences when those hazardous gases and fine particles are inhaled, and the impact of poor air quality caused by smoke may also be detrimental in the long term.

“There are probably some longer-term effects of those small particles that we don’t fully understand yet,” Tedeschi said. “They get deep into the lungs, they probably cause more inflammation, and may be responsible for more chronic diseases. Coupled with the heat, that’s a really dangerous combination.”

Heat and drought — which have been linked to climate change — are also prime conditions for a more intense wildfire season, and it’s expected to get worse as our planet warms, with Canada's natural resources agency saying that climate change may double the amount of area burned each year by the end of this century.

Smoke rises from the Texas Creek wildfire in British Columbia on July 9.
Smoke rises from the Texas Creek wildfire in British Columbia on July 9. (BC Wildfire Service/Handout via Reuters)

“I think about kids that are exposed to poor air quality chronically, and that is absolutely a risk for chronic asthma,” Tedeschi said. “If you look at asthma rates and look at heat index and access to green spaces, there’s a lot of correlation. And so I worry about kids, for instance, being exposed to poor air quality in such a way that either they develop respiratory problems, or the ones they already have, over the course of a lifetime, can get worse.”

Those milder winters and earlier springs that make for a ripe wildfire season are also giving disease-carrying insects like mosquitoes and ticks the opportunity to thrive longer and expand their habitats to new, warmer corners of the U.S. The Centers for Disease Control and Prevention says that between 2004 and 2018, reported illnesses from mosquito, tick and flea bites more than doubled to more than 760,000 reported cases nationwide.

And that’s not all that’s booming as temperatures rise. The emergence of new, sometimes deadly fungi with the ability to infect humans is now a major concern for the World Health Organization, with Dr. Andrej Spec, a fungal infections expert at Washington University School of Medicine in St. Louis, telling Yahoo News, “As we warm up, we lose one of our biggest protections against fungi: our body temperature.”

Fungi, Spec explained, don’t do well at 98.6°F — the average body temperature of humans — and thrive best at temperatures around 77°. But more instances of extreme heat are weeding out those fungi that can survive only a temperate environment and allowing more heat-resistant fungi to thrive.

A computer illustration of the fungus Candida auris.
A computer illustration of the fungus Candida auris, which causes drug-resistant infections and has high mortality rates. (Science Photo Library/Getty Images)

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The myriad of health problems stemming from more and more extreme heat will also exacerbate another, separate problem that’s been decried by doctors and medical professionals for years — the health care worker shortage.

“Nationwide, our emergency departments are overwhelmed and overburdened and overcrowded,” Tedeschi said. “And when you think about an event that might drive lots of excess people to an emergency department, like a heat wave or bad air quality event, our ER overcrowding is probably one of our greatest risks when it comes to mitigating these climate disasters.”