Scientists Try To Determine When A Heat Wave Goes From Uncomfortable To Deadly

Areas across the U.S. and around the world are experiencing some extreme heat this summer … and those temperatures can quickly lead to catastrophic results.

More than three dozen U.S. deaths have been attributed to heat this season, and experts say climate change is likely to exacerbate the situation in years to come.

What’s the limit?

While air conditioning is quite literally a lifesaver in regions prone to extreme heat, many communities lack reliable access. This fact has fueled research into the human body’s threshold for high temperatures.

Various environmental and anatomical factors determine how much heat a person can stand before experiencing serious illness or death. And scientists have accounted for those variables in an attempt to reflect how vulnerable we are to the impact of extreme heat.

Moisture, or lack thereof

In areas with high humidity, sweat doesn’t evaporate and “the outside of your skin can’t get cooler than the inside of your skin,” explained professor Scott Denning.

This can quickly lead to overheating, heat stroke, or even death.

On the other hand, dry heat presents its own problems — particularly for older individuals who have a reduced ability to sweat effectively. This can lead to an elevated risk of heat stroke even in shaded areas with low humidity when temperatures soar into the triple digits.

There’s no magic number

As Arizona State University’s Jennifer Vanos explained: “There will never be one threshold to survivability, and thinking that way is dangerous.”

But there is one measurement, known as the “wet-bulb temperature,” that can offer some general guidance. This refers to the reading of a thermometer covered with a wet cloth, which mimics the effect of sweat on your skin.

“The wet-bulb temperature has to be a few degrees cooler than the inside of your body,” concluded Denning.

Chris Agee July 12th, 2024

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