Health

Keeping kids safe in extreme heat

Experts outline threats to childhood development, school challenges, play-time risks

Anna Lamb

Harvard Staff Writer

August 12, 2025

4 min read

With heat waves becoming more intense and frequent across the U.S., experts gathered for a Harvard webinar on how to protect children’s health amid soaring temperatures.

“Extreme heat is really one of the most dangerous but also one of the least recognized threats to healthy development,” said Lindsey Burghardt, chief science officer at Harvard’s Center on the Developing Child, which hosted the talk.

According to Burghardt, extreme heat has been linked to premature birth, low birth weight, disruptions in sleep and learning, and negative effects on mental health.

Outdoor playgrounds can turn into miniature heat islands — areas that increase dangerous heat even more.Jennifer Vanos

“These outcomes are really important for us to understand,” she said. “Because they have immediate effects in childhood, but they also have the ability to have effects and impacts across children’s lifetimes. This makes intervention just so important.”

The Environmental Protection Agency defines extreme heat days as those in which outside temperatures exceed 95 degrees Fahrenheit. It also encompasses periods in which temperatures fail to drop, even at night. According to EPA statistics, these types of heat waves are becoming more frequent and severe.

Joining Burghardt in the talk was Michelle Kang, chief executive officer for the National Association for the Education of Young Children. She said her team has worked with Harvard’s Graduate School of Education to analyze how the changing climate affects learning and childcare practices across the country.

“Ideally, you’re able to take children out at times to have that gross motor play — that important time where they’re able to get those zoomies out,” she said. “But if you don’t have adequate shade, and it’s hot and getting hotter, then you actually can’t take your children outside. It changes what the learning environment looks like for the day to day and creates more stress on educators to ensure that they have what they need to keep their children safe.”

According to listening sessions with members of her organization, Kang said educators across the country are dealing with vastly different resources to keep kids cool during increasingly hot spring semesters and summer sessions. Many school buildings lack adequate air conditioning, for example, or fail to insulate against the extreme heat.

Another speaker, Jennifer Vanos, associate professor in the School of Sustainability and the College of Global Futures at Arizona State University, added that many schools also lack sufficient indoor play space.

Outdoor playgrounds, said Vanos, can turn into miniature heat islands — areas that increase dangerous heat even more.

“It really comes down to an individual school, and what their environment is like. What are their indoor conditions like? What are their outdoor conditions like? Some schools have really great shaded designs that are still OK to be playing in under slightly hotter weather,” she said. “Some schools can handle it better than others.”

During times of extreme heat, she said, it’s important for parents and educators to monitor play time.

“Kids want to keep playing,” she said. “What can happen if we don’t stop that soon enough is you’ll start to see the rise in the heart rate, because they’re trying to pump blood to the skin to lose heat from the body, and then you’ll also start to see a rise in sweat rate.”

Because kids have fewer sweat glands than adults, they aren’t able to release heat at the same rate, Vanos said. At the point when they’re getting sweaty, their core temperature is dangerously rising.

“If you see that rise above 104 degrees Fahrenheit or so, that’s when you can get into this very high risk of heat stroke occurring, or, if you’re playing, it’s more exertional heat stroke or a heat exhaustion,” she said.

In the direst cases of extreme heat exposure, the body can experience multiple organ failure and need hospitalization. And while it happens quickly, Vanos said, there are signs that indicate it’s time to cool off.

“One child is very different from another child, and we have to know which kids have potential pre-existing factors to account for certain medications, certain illnesses that they might have that make them higher risk than average,” she said. “We have to figure out the intervention points there — what are they, and how can we keep kids safe.”