• Posted July 13, 2024

Respect Summer's Scorching Heat, Experts Warn

The human body is no match for extreme heat, and scorching temperatures seem to be the rule rather than the exception these days.

"It's hard to think of an organ that is not affected by the heat," said Craig Crandall, professor of internal medicine at UT Southwestern in Dallas. 

Extreme heat means temperatures above 90 degrees, along with high humidity -- a combo that can wreak havoc on the body's internal systems and even cause organs to fail.

"What keeps us cool is sweat evaporating from our skin," Crandall said in a UT Southwestern news release. "When the weather is too humid, sweat does not evaporate as effectively, so with the excess sweating, you're essentially just dehydrating yourself."

Heat stress causes blood to rush to the skin to release body heat. That forces the heart to pump harder, which can be especially hazardous for people with cardiovascular diseases. 

Kidney function may also be impaired, putting people with renal disease at risk. Breathing is harder, and hot, humid air can trigger asthma symptoms or make them worse. The intestinal tract may also allow harmful toxins to enter the bloodstream.

And overexertion in extreme heat may cause muscle strains, cramps and even a serious condition called rhabdomyolysis that can harm the kidneys and cause an irregular heart beat.

It's important to understand when someone is struggling with the heat and to get help fast if it happens.

Last summer -- the hottest on record -- saw nearly 120,000 visits to emergency rooms across the United States and 2,302 heat-related deaths, up from 1,602 in 2021, federal data show. This summer is shaping up to be the same.

Two of the biggest concerns are heat exhaustion and heat stroke.

"Heat exhaustion is not likely to inflict significant damage if addressed early," said Dr. Kurt Kleinschmidt, a professor of emergency medicine at UT Southwestern. "In contrast, heat stroke is far more dangerous. By then, your body temperature has risen so much that organs, such as the brain, are shutting down. If not recognized early, heat exhaustion can progress to heat stroke."

Common symptoms of heat exhaustion include headache or dizziness, weakness, nausea, irritability, heavy sweating, elevated body temperature, decreased urination and thirst. A person may even develop neurological symptoms -- becoming confused, delirious and having seizures.

Recognizing the symptoms of heat stroke could be the difference between life and death, the doctors emphasized.

To protect yourself and loved ones, stay hydrated; go indoors if you begin to feel tired, dizzy or overheated; wear lightweight clothing; and pay attention to the heat index. Stay inside at the hottest times of days and during heat advisories. To cool down, wipe your skin down with a wet cloth. And keep a watch on older older relatives who live on their own. 

More information

There's more about the health effects of heat waves at the Union of Concerned Scientists.

SOURCE: UT Southwestern Medical Center, news release, July 5, 2024