As temperatures rise above 100 in many places around the U.S., Kristina Dahl of the Union of Concerned Scientists explains warning signs for heat-related illnesses and tips for staying cool.



It's only the second day of summer, and temperatures in the U.S. are already dangerous to human health. Last week it was 105 in Omaha, 118 in Phoenix and 123 in Palm Springs. This will become more common as the Earth heats up, so we're going to talk with Kristina Dahl about how people can protect themselves as another hot summer unfolds. She's a senior climate scientist with the Union of Concerned Scientists.

Good to have you here.

KRISTINA DAHL: It's great to be here.

SHAPIRO: Before we get to practical steps that people should be taking, how unusual are these kinds of temperatures so early in the season?

DAHL: It is very unusual to have such intense and such long-lasting heat so early in the season. I mean, typically, we see places reaching these kinds of temperatures at the hottest parts of the summer - you know, late July, August, sometimes even early September. But it is quite unusual to be seeing so many records being broken even before the official start of the summer season.

SHAPIRO: Yeah. And every year, we hear of people in the U.S. dying from overexposure to heat. Which groups are most at risk?

DAHL: That's right. We often call heat the silent killer. Of all of the types of extreme weather, people die from extreme heat the most. It typically kills more people in a given year than something like hurricanes or droughts.


DAHL: So it is extremely important to be taking care of our health when we're experiencing extreme heat. The people who tend to be most at risk are elderly adults. As you become older, your body has more trouble regulating your temperature. And so adults have a harder time shedding the heat that accumulates in their bodies when it's extremely hot outside. We also see high risks to athletes. When we are young and healthy, it's harder to listen to those early signals of heat illness that your body's trying to give you. And so we do, unfortunately, every year see people who are otherwise fit and healthy passing away due to extreme heat exposure.

SHAPIRO: Well, let's talk about those specific groups. I mean, for senior citizens, what do you recommend people do to protect themselves or their neighbors or older relatives?

DAHL: So it's important, if you're not elderly, to be checking in on your elderly neighbors and relatives, making sure that they have the opportunity to cool off. If you are an elderly adult, being aware of how heat can affect your health is really important. So some of those early symptoms include things like dizziness or headache or feeling extremely tired. And so if you're experiencing those, no matter what your age, make sure that you take some time to lie down and rest. Drink water. And if you can, get to a cool place.

SHAPIRO: There are people who have to work outdoors no matter the weather, perhaps in construction or landscaping. Beyond being aware of the symptoms of heatstroke, are there things they can do to help maintain their health even in these extreme temperatures?

DAHL: So in those cases, people do need to be aware of what those early symptoms of heat-related illness are. But the onus is also on employers to be providing adequate hydration breaks, rest breaks, shade, cooling, maybe even shifting work hours to earlier, cooler times of the day. So we can't put all of the onus on the workers themselves because often, the work is designed in ways that disincentives taking breaks.

SHAPIRO: You said that young and otherwise healthy people sometimes overexert themselves, thinking that they are invincible. So if you are a parent or a coach or a student athlete, what would you suggest those groups look out for?

DAHL: When it comes to heat, it's incredibly important not to overexert yourself because when it's really hot out, when it's really humid out, your body has a harder time shedding heat that accumulates within it for a number of reasons. For example, if it's very humid, it becomes harder for the sweat on your skin to evaporate. And it's that evaporation of sweat that really provides the cooling effect to your body.

SHAPIRO: I'm just thinking - I live in Washington, D.C., a notoriously hot and humid city. And I love to go out for a run and sweat it all out and get exhausted. And it sounds like you're saying I am gambling with my health by doing that. Maybe I should reconsider it.

DAHL: I would just say pay attention. You know your body, and you know its limits. So it's not that you have to completely cease doing outdoor exercise in the heat, but just pay attention. And if you're starting to feel dizzy, if you're starting to get a headache, if you're starting to really lag, listen to those warning signs that your body is giving you, and take a break.

SHAPIRO: Kristina Dahl is a senior climate scientist with the Union of Concerned Scientists.

Thanks for helping us launch this summer season.

DAHL: Thanks so much. Transcript provided by NPR, Copyright NPR.