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As a summer heat wave pummels the US, an expert warns about the dangers of humidity – particularly for toddlers, young athletes and older adults (The Conversation)

Posted: Jul 17, 2023 in In the News

This article originally appeared in The Conversation on July 17, 2023.

 

As a summer heat wave pummels the US, an expert warns about the dangers of humidity – particularly for toddlers, young athletes and older adults

By W. Larry Kenney

Because of climate change, summers are getting hotter and more humid – much more humid. SciLine interviewed Dr. W. Larry Kenney, professor of physiology and kinesiology at Penn State University, who discussed why humid heat can be dangerous to human health and, in some cases, life-threatening; how heat stresses the body, particularly the cardiovascular system; and why infants, athletes and older adults are especially susceptible.

How is climate change affecting the frequency and severity of heat waves in the U.S.?

Kenney: When climatologists talk about the changing climate and global warming, the focus is on the average temperature on Earth – the average surface temperature, the average ocean temperature and so on. Humans are tropical animals; we evolved in tropical climates. And so a change of a couple of degrees Fahrenheit in the average Earth’s temperature doesn’t have much of an effect on human health directly.

However, if you think of the range of climates as a bell-shaped curve, and then think of that whole curve shifting toward hotter temperatures, it’s the extremes that are dangerous. So we’ll have more hot days and more extremely hot days, which result in an increased frequency, duration and intensity of environmental heat waves.

Why is humid heat particularly dangerous?

Kenney: The primary means by which humans get rid of body heat that’s built up is by evaporation of sweat. The more humid it is, the less of the sweat that we produce evaporates, and the less of that powerful cooling mechanism we have at our disposal.

Other than sweating, how does the body respond to heat stress?

Kenney: The other way we cope with increased body temperature is unique to humans. We pump a lot of blood to the skin to dissipate heat to the environment. So under extremely hot resting conditions, we may pump as much blood to the skin as we pump to the entire rest of the body.

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Read the full article here.