MICHEL MARTIN, HOST:
A different subject now. Little kids can really struggle in the heat. Their bodies don't sweat as efficiently as adults' bodies do, and they have to rely on adults to find the relief of air conditioning or shade. NPR's Jonathan Lambert reports on new research suggesting that for some children, exposure to extreme heat could lead to potentially lifelong setbacks.
JONATHAN LAMBERT, BYLINE: The first few years of life are really important. That's when kids develop the key physical, cognitive and social skills that can shape the rest of their lives. Jorge Cuartas is a researcher at NYU. He says these skills seem really simple.
JORGE CUARTAS: Things like recognizing common letters or words, recognizing numbers, being able to grasp small objects with two fingers.
LAMBERT: But developing them at the right time can impact all kinds of outcomes from mental health to economic success. Our brains build these skills in part by being extra sensitive, soaking up all those early experiences like sponges. That can be good and bad.
CUARTAS: If we experience adversities, if we experience excessive stress, that can lead to long-lasting impacts on brain development.
LAMBERT: Given little kids are especially vulnerable to extreme heat, Cuartas wanted to see if exposure to it could have the same long-lasting impacts as other kinds of stress. He focused on 3- and 4-year-olds.
CUARTAS: Early childhood is a sensitive period of development.
LAMBERT: Across several low- to middle-income countries, his team combined climate records with data showing when kids hit developmental milestones. Altogether, they looked at nearly 20,000 children, and they found that those who experienced extreme heat - even just one month with average highs that topped 86 degrees - were less likely to be developmentally on track.
CUARTAS: I was quite surprised to see that we could still identify these very specific impacts on development starting during these early years.
LAMBERT: The results were published in the Journal of Child Psychology and Psychiatry. They also showed that kids from the lowest-income households were the most affected by heat. That early setback can build on itself as kids grow up.
CUARTAS: Early disparities not only are present later in life but also tend to expand.
LAMBERT: Making it more difficult, for example, to complete their education. The study can't say why heat has these effects on a child's development. It could be messing with kids' sleep or preventing them from going outside to play. Lindsey Burghardt is chief science officer at the Center for (ph) the Developing Child at Harvard.
LINDSEY BURGHARDT: It's increasingly clear that temperature matters, that living, growing, sleeping, learning, playing with a comfortable temperature really matters for children's well-being.
LAMBERT: She says this study points out the problem but also outlines potential solutions. Air conditioning isn't available in many parts of the world, but lower-tech solutions like expanding access to clean water for keeping cool and hydrated or creating more shade could help kids stay on the right track.
Jonathan Lambert, NPR News.
(SOUNDBITE OF LOWERCASE NOISES' "THE HUNGRY YEARS") Transcript provided by NPR, Copyright NPR.
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