Heat Waves Can Be Dangerous, Even If You're Young

Woman hydrating.

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Key Takeaways

  • A new study shows that during days of extreme heat, people under the age of 64 are at a higher risk of visiting the emergency department than adults over the age of 75.
  • Extreme heat is set to become more intense and more frequent due to climate change.
  • It's crucial to know how to stay safe and healthy during periods of extreme heat.

Nicole Villegas was just 32 years old when she set out on a mountain bike ride through a dense forest. She found herself in the emergency room by the end of the day. 

“People in my life were surprised to hear this reality,” Villegas told Verywell. She’s always prioritized her wellness and encourages others to drink water, eat enough food, and rest, she said.

“This day was no different," she added. "I took all the precautions I could."

But her legs began to feel “like heavy, numb tree trunks,” and her eyes didn’t know where to focus. She blacked out, had a severe heat stroke, and has been recovering from the brain swelling injury ever since. 

“I now realize how important it is to notice how your body is acclimated to where you spend the most time,” Villegas said. Although she hydrated with electrolyte drinks, wore cool cotton clothing, and stayed in the shade as much as possible, the heat got to her.

“This is your physical adaptation to your average climate," she said. "My body was used to 80 to 90 degree summers, not a 116-degree heat dome."

Research published this month in The British Medical Journal found that, during days of extreme heat, young and middle-aged people under the age of 64 are at a higher risk of visiting the emergency department than adults over the age of 75.

These findings may be surprising for some. Research and media discourse about heat strokes and the impact of extreme heat often focuses on older adults.

But it is a growing problem. Extreme heat is a leading cause of death in the U.S. when it comes to weather-related problems. And it is set to become more intense and more frequent as we continue to experience climate change.

Heat and Emergency Department Visits

“Heat is an important threat to public health. In order to reduce the risks of extreme heat, each of us needs to be aware of the health risks and take measures to reduce their exposure as much as possible,” Gregory Wellenius, lead study author and professor of environmental health and director of the program on climate and health at Boston University School of Public Health, told Verywell. “The public health and medical community need to be ready to help those that don't have the resources to help themselves on the hottest days.”

The researchers looked for patterns between days of extreme temperatures and the number of emergency department visits. They pored over anonymous health insurance records for nearly 22 million people who visited the emergency department across about 3,000 American counties between 2010 and 2019, during the months between May and September. 

As a result, the scientists noted that during the days of extreme temperatures—days that were at least 93 degrees—there was a 7.8% increase in patients visiting the ER across all ages for many different ailments.

For example, there was a 66% increased risk of visits for heat-related illnesses like heat fatigue, cramps, exhaustion, and heatstroke. There was also a 30% increase in visits for chronic kidney disease and a 7.9% increase for mental health concerns. Recent studies have shown that heat waves tend to exacerbate mental health concerns.

But the numbers were higher for adults between 18 and 64 years of age. The risk was 10.3% higher for people aged 45 to 54, in comparison to 3.6% higher for those over 75 years of age. Emergency department visits were most often on the initial date of the temperature rise, with some continued visits over the next couple of days.

“The findings from this study show that heat can pose a threat to the health of all adults in the U.S., regardless of age or where you live," Wellenius said. "So it is not just the elderly that are vulnerable to the effects of heat. We all need to be aware of the risks and we all need to be prepared."

Wellenius points out that it was important to look at emergency department visits and not hospitalizations because many issues exacerbated by extreme heat can be taken care of in a short period of time, especially for younger people, and wouldn’t result in hospitalization. It's also important to look at these results stratified over a long period of time because they show a pattern rather than the spiking result of a one-off heatwave.

However, Villegas, who is an occupational therapist who was not involved in this research, notes that this study solely looked at data from health insurance. Non-insured people affected by extreme heat are important to consider, too. There may even be a higher risk for day laborers, farmworkers, service workers, and people in the industrial sector who may work in environments not well equipped for heat, and may not have health insurance.

For future research, experts point out that children should be considered as well.

"Although we have a good understanding of the risks heat poses to the health of adults, we know much less about the health effects of heat on children and adolescents," Wellenius said. "We need more research to understand the effects of heat on children, and other potentially vulnerable groups."

What This Means For You

Save a list of the signs of heat-related illness on your phone or in your wallet, and talk to a friend about the signs. Talking about the signs and your preventative measures helps build your awareness into a habit so that you can respond with confidence and even save a life.

Are We Not Well Prepared for the Heat?

“I like that these findings get us talking," Villegas said. "Now, we can look at what’s currently happening and take steps in our communities to reduce risk of heat-related illness and injury for all ages."

On one hand, this spike in heat-related illness among younger populations might be due to carelessness or unpreparedness among people who didn’t think they’d have to worry about this issue. Research like this can help raise awareness and help public health officials reach out to people that wouldn’t know extreme heat is a threat to them.

Especially because heat-related hospital visits are largely preventable, and anybody can benefit from taking preventative measures. The public health response to prevent heat illness and injury in children and older adults can be adapted to for other ages as well.

On the other hand, there may also be a lack of federal, state, and local policy addressing extreme heat in places where it typically isn’t an issue.

In fact, periods of extreme heat led to about 4% higher risk of emergency department visits in southeastern states, the warmer states, but about 10% in the Midwest, and about 12% in the northeast. If you live in a cooler, non-tropical continental climate, you’re less likely to have air conditioning and you may be more vulnerable to heat, according to the study.

These statistics could be curbed through well-informed policy changes, with politicians and health experts working together to find household, urban, and community solutions.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Sun S, Weinberger K R, Nori-Sarma A, Spangler K R, Sun Y, Dominici F et al. Ambient heat and risks of emergency department visits among adults in the United States: time stratified case crossover study BMJ 2021; 375 :e065653 doi:10.1136/bmj-2021-065653

  2. The Weather Channel. America's No. 1 Weather Killer is Not Tornadoes, Flooding, Lighting, or Hurricanes.

  3. The National Academies of Sciences Engineering Medicine. Global warming makes heat waves hotter, longer, and more common.

  4. Liu J, Varghese BM, Hansen A, et al. Is there an association between hot weather and poor mental health outcomes? A systematic review and meta-analysisEnviron Int. 2021;153:106533. doi:10.1016/j.envint.2021.106533

By Sofia Quaglia
Sofia Quaglia is a science and health writer based between Italy, the United Kingdom, and the United States.