Health

When heat waves turns deadly: How extreme temperatures affect the human body

Published

2 years ago

June 22, 2024

When heat waves turns deadly: How extreme temperatures affect the human body

As temperatures and humidity soar outside, what’s happening inside the human body can become a life-or-death battle decided by just a few degrees.

The critical danger point outdoors for illness and death from relentless heat is several degrees lower than experts once thought, say researchers who put people in hot boxes to see what happens to them.

With much of the United States, Mexico, India and the Middle East suffering through blistering heat waves, worsened by climate change, several doctors, physiologists and other experts explained to The Associated Press what happens to the human body in such heat.

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Heat waves can raise your body temperature

The body’s resting core temperature is typically about 98.6 degrees Fahrenheit.

That’s only 7 degrees away from catastrophe in the form of heatstroke, said Ollie Jay, a professor of heat and health at the University of Sydney in Australia, where he runs the thermoergonomics laboratory.

Dr. Neil Gandhi, emergency medicine director at Houston Methodist Hospital, said during heat waves anyone who comes in with a fever of 102 or higher and no clear source of infection will be looked at for heat exhaustion or the more severe heatstroke.

A man pours cold water onto his head to cool off on a sweltering hot day in the Mediterranean Sea in Beirut, Lebanon, on July 16, 2023. As temperatures and humidity soar, what’s happening inside the human body can become a life-or-death battle decided by just a few degrees. (AP Photo/Hassan Ammar, File)

“We routinely will see core temperatures greater than 104, 105 degrees during some of the heat episodes,” Gandhi said. Another degree or three and such a patient is at high risk of death, he said.

How heat kills

Heat kills in three main ways, Jay said. The usual first suspect is heatstroke — critical increases in body temperature that cause organs to fail.

When inner body temperature gets too hot, the body redirects blood flow toward the skin to cool down, Jay said. But that diverts blood and oxygen away from the stomach and intestines, and can allow toxins normally confined to the gut area to leak into circulation.

“That sets off a cascade of effects,” Jay said. “Clotting around the body and multiple organ failure and, ultimately, death.”

But the bigger killer in heat is the strain on the heart, especially for people who have cardiovascular disease, Jay said.

It again starts with blood rushing to the skin to help shed core heat. That causes blood pressure to drop. The heart responds by trying to pump more blood to keep you from passing out.

“You’re asking the heart to do a lot more work than it usually has to do,” Jay said. For someone with a heart condition “it’s like running for a bus with dodgy (hamstring). Something’s going to give.”

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The third main way is dangerous dehydration. As people sweat, they lose liquids to a point that can severely stress kidneys, Jay said.

Many people may not realize their danger, Houston’s Gandhi said.

Dehydration can progress into shock, causing organs to shut down from lack of blood, oxygen and nutrients, leading to seizures and death, said Dr. Renee Salas, a Harvard University professor of public health and an emergency room physician at Massachusetts General Hospital.

“Dehydration can be very dangerous and even deadly for everyone if it gets bad enough — but it is especially dangerous for those with medical conditions and on certain medications,” Salas said.

Dehydration also reduces blood flow and magnifies cardiac problems, Jay said.

Intense heat can ‘fry’ your brain

Heat also affects the brain. It can cause a person to have confusion, or trouble thinking, several doctors said.

“One of the first symptoms you’re getting into trouble with the heat is if you get confused,” said University of Washington public health and climate professor Kris Ebi. That’s little help as a symptom because the person suffering from the heat is unlikely to recognize it, she said. And it becomes a bigger problem as people age.

One of the classic definitions of heat stroke is a core body temperature of 104 degrees “coupled with cognitive dysfunction,” said Pennsylvania State University physiology professor W. Larry Kenney.

Heat and humidity are a dangerous duo

Some scientists use a complicated outside temperature measurement called wet bulb globe temperature, which takes into account humidity, solar radiation and wind. In the past, it was thought that a wet-bulb reading of 95 Fahrenheit was the point when the body started having trouble, said Kenney, who also runs a hot box lab and has done nearly 600 tests with volunteers.

His tests show the wet-bulb danger point is closer to 87. That’s a figure that has started to appear in the Middle East, he said.

And that’s just for young healthy people. For older people, the danger point is a wet bulb temperature of 82, he said.

“Humid heat waves kill a lot more people than dry heat waves,” Kenney said.

When Kenney tested young and old people in dry heat, young volunteers could function until 125.6 degrees, while the elderly had to stop at 109.4. With high or moderate humidity, the people could not function at nearly as high a temperature, he said.

“Humidity impacts the ability of sweat to evaporate,” Jay said.

How to cool down heat exhaustion patients

Heatstroke is an emergency, and medical workers try to cool a victim down within 30 minutes, Salas said.

The best way: Cold water immersion. Basically, “you drop them in a water bucket,” Salas said.

But those aren’t always around. So emergency rooms pump patients with cool fluids intravenously, spray them with misters, put ice packs in armpits and groins and place them on a chilling mat with cold water running inside it.

Sometimes it doesn’t work.

“We call it the silent killer because it’s not this kind of visually dramatic event,” Jay said. “It’s insidious. It’s hidden.”

Health

Common nighttime noise exposure may trigger heart problems, study suggests

Published

4 hours ago

February 28, 2026

Press Room

Common nighttime noise exposure may trigger heart problems, study suggests

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Living near heavy traffic could negatively impact your heart health.

A European study, published in the journal Environmental Research, found that exposure to nighttime road traffic noise is linked to changes in the blood, leading to worsened cholesterol and cardiovascular risks.

The researchers considered data from the U.K. Biobank, Rotterdam Study, and Northern Finland Birth Cohort 1966, including more than 272,000 adults over the age of 30, according to a press release.

Nighttime road noise exposure was estimated at all participants’ homes based on national noise maps. Researchers also took blood samples to measure the participants’ metabolic biomarkers for disease, then mapped the link between nightly noise levels and existence of biomarkers.

Exposure to loud noise was associated with increased concentrations of cholesterol-related biomarkers. (iStock)

The study found that people exposed to louder noise at night — especially sounds above 55 decibels — showed changes in 48 different substances in their blood. Twenty of these associations “remained robust” throughout all cohorts.

Exposure to loud noise was associated with increased concentrations of cholesterol-related biomarkers, especially LDL “bad” cholesterol, IDL (intermediate-density lipoprotein) and unsaturated fatty acids.

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As noise levels increased, starting at around 50 decibels, cholesterol markers rose steadily, the release stated.

The authors concluded that this study “provides evidence that nighttime road traffic noise exposure from 50 dB upward is associated with alterations in blood cholesterol and lipid profiles in adults.”

Researchers noted a link between traffic noise and cardiometabolic disease. (iStock)

Study co-author Yiyan He, doctoral researcher at the University of Oulu in Finland, noted that in this type of research, small effect sizes are expected, and environmental exposures such as traffic noise are “typically modest.”

SIMPLE NIGHTLY HABIT LINKED TO HEALTHIER BLOOD PRESSURE, STUDY SUGGESTS

“Despite this, we observed statistically robust and consistent associations across many biomarkers, especially those related to LDL and IDL lipoproteins,” she told Fox News Digital.

MISSING SLEEP MAY TAKE A HIDDEN TOLL ON YOUR BRAIN AND LONGEVITY, RESEARCH REVEALS

“We also identified a clear exposure-response pattern starting at around 50 dB, suggesting that metabolic changes become more evident as noise levels increase.”

This aligns with public health guidance, as the World Health Organization recommends lower nighttime noise limits at around 40 to 45 dB, Yiyan He added.

“This finding may clarify the association between traffic noise and cardiometabolic diseases,” the researchers wrote. (iStock)

“The 55 dB level is often used as an interim benchmark associated with substantial noise annoyance and sleep disturbance,” she said. “In our study, we observed associations not only at 55 dB, but also indications of effects emerging at around 50 dB.”

The strength and consistency of the cholesterol-related associations were surprising, as these changes are usually “subtle.”

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“Instead, we found consistent associations across multiple large European cohorts, which strengthens confidence that the findings may reflect real biological patterns,” Yiyan He went on. “We were also interested to see that effects were minimal below ~50 dB, suggesting a possible threshold-like pattern.”

HEART DISEASE THREAT PROJECTED TO CLIMB SHARPLY FOR KEY DEMOGRAPHIC

The researcher noted that these findings were consistent across genders, education levels and obesity status.

The study was restricted to White Europeans, which posed a limitation. There was also a lack of information on the fasting status in the UK Biobank.

Changes in cholesterol levels were more severe than researchers expected. (iStock)

“Fasting can influence levels of certain metabolites, particularly fatty acids,” Yiyan He said. “However, based on UK Biobank documentation, fewer than 10% of participants were fasting for at least eight hours, and our main findings focused on cholesterol-related biomarkers, which are generally less sensitive to short-term fasting.”

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The researchers also lacked information on bedroom location, indoor noise exposure and time spent at home.

“These factors may introduce non-differential exposure misclassification,” Yiyan He said. “Additionally, noise exposure estimates were based on participants’ temporary residential addresses at the time of blood sampling, without considering the duration of residence.”

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“Many of these limitations would tend to bias results toward the null, so the consistent associations we observed remain noteworthy.”

Experts recommend taking measures to limit traffic noise at night. (iStock)

Based on this latest research, Yiyan He noted that nighttime noise is a “health-relevant exposure,” not just “an annoyance.”

“Our findings suggest that nighttime traffic noise may subtly but consistently affect metabolic health,” she said. “While the changes in cholesterol and lipid levels for any one individual are small, traffic noise affects a very large number of people, which means the potential public health impact could be substantial.”

TEST YOURSELF WITH OUR LATEST LIFESTYLE QUIZ

The researcher recommends taking measures like improving sound insulation, using noise-reducing strategies and placing bedrooms on the quieter side of the home when possible.

“Because sleep is a key pathway linking noise to health, protecting the nighttime sleep environment is especially important,” she added.

Angelica Stabile is a lifestyle reporter for Fox News Digital.

Health

The Best Time To Drink Coffee for Weight Loss and a Faster Metabolism

Published

15 hours ago

February 27, 2026

Press Room

The Best Time To Drink Coffee for Weight Loss and a Faster Metabolism

The Best Time To Drink Coffee for Weight Loss and Fat Burn | Woman’s World

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