You're listening to shortwave from NPR.

Hey, Sharwhavers, Regina Barber here with Lauren's summer,

one of NPR's climate correspondence. Hey, Lauren.

Hey, Dina. So today, we're starting with an experiment that's designed to make you sweat.

Well, I am an already sweaty person and actually thinking about climate change doesn't help,

but you know, I'm going to do it. I'm ready.

Okay. Well, then this is going to be like the perfect Venn diagram of that.

It's at Penn State University inside this climate-controlled room.

And if you're in the study, you go in and you either sit there or walk slowly on a treadmill.

Okay. That doesn't sound so bad. I could do that.

Yeah. Well, here's what Professor of Physiology, Larry Kenney, does next.

We start to increase the humidity every five minutes in a stepwise fashion.

Oh, okay. That sounds awful. As a Westcoaster, I am very bad with humidity.

I'm too. And in that room, it's getting really muggy.

And then the test subjects, they've also all this tiny electronic device that shaped like a pill

and it records their core temperature. Cool.

And what Kenney is looking for is what he calls the critical environmental limit.

The combination of temperature and humidity beyond which either they can't sweat enough or they

can't evaporate enough sweat to maintain their body temperature.

I feel like I'm actually very familiar with that moment. You feel really sticky and uncomfortable.

Yeah. Yeah. Like the sweat is kind of pooling on your skin.

Only sweat that evaporates has any ability to cool the body.

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