ARI SHAPIRO, HOST:

OK, it is not news that the Midwest gets cold in the winter. But this week could be the coldest in a generation. Today parts of the Dakotas and Minnesota hit -27 degrees. That's not just uncomfortable, it's dangerous. To understand what those kinds of temperatures do to the human body, Dr. Jeff Schaider joins us now. He's chairman of Emergency Medicine at Cook County Health in Chicago. Thanks for being with us.

JEFF SCHAIDER: Hi, Ari.

SHAPIRO: OK, I spent the first eight years of my life in Fargo, N.D., so I know what extreme cold feels like. But what is actually happening physiologically to our skin and our lungs when our bodies are exposed to these temperatures that are so far below zero?

SCHAIDER: Well, I think, you know, obviously it's a stress on the body. And I generally divide it into two phases as far as the cold goes. Number one, people often think about the cold affecting you on your skin in frostbite. And the other thing is when your body temperature drops as a result of being exposed to the cold more prolonged. And obviously, you know, both these things can cause severe injuries, sometimes death as well.

SHAPIRO: In the kinds of temperatures we're talking about - I mean, as far as 25 below zero - how long does it take for those kinds of effects to set in?

SCHAIDER: From a frostbite perspective, I've seen patients develop frostbite with an approximate 10 to 15 minutes after being exposed to these extreme temperatures. So people would actually get outside, you know, walk down the street for about 10 minutes or so and develop frostbite in the back of their ears by not wearing a hat. So, you know, we always tell people very, very important - this is common sense obviously - they need to cover their extremities to not be exposed to these extreme temperatures.

SHAPIRO: And in terms of the internal effects when the body temperature cools that you were describing?

SCHAIDER: Exactly. So that's what - we call it medically when the body temperature goes lower, it's called hypothermia. Initially when you're exposed to the cold you'll obviously shiver and try to warm your body up. That's your initial response. But as your body gets colder and colder, your response to the cold actually becomes less and less. You'll stop shivering then your body temperature will start dropping at a more rapid rate. And if you think about your body as I guess an engine, as it gets colder it moves slower. Your mind thinks slower. Your heart moves slower. And as time goes on, you become confused. You can go into a coma. And your heart would go slower. Your blood pressure will drop. And it really affects your whole body. And people could die from the cold in these types of circumstances.

SHAPIRO: Are there common mistakes that people make when they try to go outside in these kinds of temperatures?

SCHAIDER: Of course. I mean, we all make mistakes. But, you know, obviously in this type of situation, if you go out and you think you will not be exposed to the cold, you have to anticipate that might happen. If you're in the car, bring additional clothes, bring a blanket, bring an extra hat, extra gloves just in case something happens to your car. Alcohol does play a role too. People that go out and drink might walk outside because they don't feel the effects of the cold that much when they're intoxicated. And then in these types of situation they might be exposed to the cold for a long period of time and their body temperature would begin to drop.

SHAPIRO: Dr. Schaider, thanks so much for talking with us today.

SCHAIDER: Ari, thank you so much.

SHAPIRO: That's Jeff Schaider, chairman of Emergency Medicine at Cook County Health in Chicago. Transcript provided by NPR, Copyright NPR.

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