A MARTÍNEZ, HOST:
A dangerous heat wave is gripping parts of the Central and Eastern United States, expected to last through the Fourth of July weekend. Temperatures could reach above 100 degrees, combined with humidity levels that make heat extra draining on the body. It comes as climate change is fueling longer and more intense heat waves across the country. Here to talk about the potential health impacts is W. Larry Kenney. He's a professor of physiology at Penn State. Professor, anything unique about the heat waves in the U.S. this year?
W LARRY KENNEY: The only thing unique is that they keep getting more frequent. They keep getting more intense and the duration of each one lasts longer, and that's a function of climate change.
MARTÍNEZ: Climate change. OK. 'Cause I was wondering, we've been seeing, it seems, every year, that things just get hotter and hotter. So, yeah, so one thing has to do with the other, in this case?
KENNEY: Absolutely. When people think of climate change, they think of small increases in mean global temperature. But that's not what really impacts human health. What really impacts human health are the extremes, that is the upper 80, 90 percentile of those temperatures.
MARTÍNEZ: So what happens then to the human body in temperatures above 100 degrees?
KENNEY: Well, there's no real limit and 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 at relative humidity over 50%, which is what we're experiencing here in the northeast right now, then there is a great impact on the human body. Body temperature increases, and that turns on our two mechanisms that we use to try to get rid of that body heat, and that is by pumping a lot of blood flow to the skin and by sweating. The sweating response is really only valuable if that sweat can evaporate. And that's the problem in high humidities.
MARTÍNEZ: OK. And what kind of people are most at risk?
KENNEY: The most vulnerable population are older men and women, and that's compounded by comorbidities like heart disease, diabetes and so on.
MARTÍNEZ: So for people, Professor, who have to be out there in the heat, what can they do to stay safe as much as they can?
KENNEY: Well, No. 1, they should slowly acclimate 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 that they're very well hydrated and make sure they drink before their heat exposures, during their heat exposures and especially afterward to try to catch up.
MARTÍNEZ: And just to be clear, Professor, when you say hydrate, that means water, not alcohol? Fourth of July weekend, I think a lot of people want to go out in the heat and have fun, and that means maybe a beer or two.
KENNEY: You know, that's true, but also a little bit of a myth.
MARTÍNEZ: OK.
KENNEY: Most things that we drink, whether it's coffee, tea, sodas, and so on are 95 or more percent water anyway. So we do hydrate when we drink those things. Research has also shown that having a little bit of low alcohol, beer or wine hydrates just as well as water. However, people need to be cognizant of the fact that the more alcohol you take in, the less hydration improvement that gives us.
MARTÍNEZ: All right. W. Larry Kenney is a professor of physiology at Penn State. Professor, thanks.
KENNEY: You're welcome.
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