TO MARTINEZ, HOST:

A dangerous heat wave is hitting parts of the central and eastern United States and is expected to last through the Fourth of July weekend. Temperatures can reach over 100 degrees, combined with humidity levels that make the heat more taxing on the body. It comes as climate change is causing longer and more intense heat waves across the country. Here to discuss the potential health impacts is W. Larry Kenney. He is a professor of physiology at Penn State. Professor, is there anything special about the heat waves in the United States this year?

W LARRY KENNEY: The only thing is that they are becoming more frequent. They are becoming more intense and the duration of each one lasts longer, and that is a function of climate change.

MARTINEZ: Climate change. OK. Because I was wondering, it seems like we’ve been seeing every year things get hotter and hotter. So, yes, does one thing have to do with the other, in this case?

KENNEY: Absolutely. When people think about climate change, they think about small increases in global average temperature. But that’s not what really affects human health. What really impacts human health are the extremes, that is, the upper 80th or 90th percentile of those temperatures.

MARTINEZ: So what happens to the human body with temperatures above 100 degrees?

KENNEY: Well, there’s no real limit or set point that makes 100 degrees unique. It’s really a combination of temperature and relative humidity. So a 100 degree day in Phoenix, Arizona is the norm because the humidity is low. But with relative humidity above 50%, which is what we are experiencing here in the Northeast right now, there is a huge impact on the human body. Body temperature increases, and that activates our two mechanisms that we use to try to get rid of that body heat, and that is to pump a large amount of blood to the skin and sweat. The sweating response is only valuable if that sweat can evaporate. And that is the problem of high humidity.

MARTINEZ: Okay. And what types of people are most at risk?

KENNEY: The most vulnerable population is older men and women, and that is compounded by comorbidities like heart disease, diabetes, etc.

MARTINEZ: Professor, so people who have to be outside in the heat, what can they do to keep themselves as safe as possible?

KENNEY: Well, number one, they should slowly acclimatize to the heat as much as possible. They should gradually increase the amount of time they spend in the heat. Secondly, they should make sure they are very well hydrated and make sure they drink before heat exposure, during heat exposure and especially after to try to catch up.

MARTINEZ: And to be clear, professor, when you say hydrate, do you mean water, not alcohol? On July 4th weekend, I think a lot of people want to get out in the heat and have fun, and that means maybe a beer or two.

KENNEY: You know, that’s true, but it’s also a little myth.

MARTINEZ: Okay.

KENNEY: Most of the things we drink, whether it’s coffee, tea, soda, etc., are 95 percent or more water anyway. So we hydrate when we drink those things. Research has also shown that drinking a little alcohol, beer or wine hydrates just as well as water. However, people should be aware of the fact that the more alcohol consumed, the less improvement in hydration.

MARTINEZ: Okay. W. Larry Kenney is a professor of physiology at Penn State. Professor, thank you.

KENNEY: You’re welcome.

(SOUNDBITE OF OFFTHEWALLY’S “PALM BREEZE”)

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