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.

HEAT WAVE LEAVES AT LEAST 125 DEAD IN MEXICO

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.”

7 WAYS TO STAY SAFE IN THIS SUMMER’S SCORCHING HEAT

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

Heart disease threat projected to climb sharply for key demographic

Published

54 minutes ago

February 27, 2026

Press Room

Heart disease threat projected to climb sharply for key demographic

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A new report by the American Heart Association (AHA) included some troubling predictions for the future of women’s health.

The forecast, published in the journal Circulation on Wednesday, projected increases in various comorbidities in American females by 2050.

More than 59% of women were predicted to have high blood pressure, up from less than 49% currently.

The review also projected that more than 25% of women will have diabetes, compared to about 15% today, and more than 61% will have obesity, compared to 44% currently.

As a result of these risk factors, the prevalence of cardiovascular disease and stroke is expected to rise to 14.4% from 10.7%.

The prevalence of cardiovascular disease and stroke in women is expected to rise to 14.4% from 10.7% by 2050. (iStock)

Not all trends were negative, as unhealthy cholesterol prevalence is expected to drop to about 22% from more than 42% today, the report stated.

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Dr. Elizabeth Klodas, a cardiologist and founder of Step One Foods in Minnesota, commented on these “jarring findings.”

“The fact that on our current trajectory, cardiometabolic disease is projected to explode in women within one generation should be a huge wake-up call,” she told Fox News Digital.

NEARLY 90% OF AMERICANS AT RISK OF SILENT DISEASE — HERE’S WHAT TO KNOW

“Hypertension, diabetes, obesity — these are all major risk factors for heart disease, and we are already seeing what those risks are driving. Heart disease is the No. 1 killer of women, eclipsing all other causes of death, including breast cancer.”

Cardiovascular disease is the leading cause of death for women in the U.S. and around the world. (iStock)

Klodas warned that heart disease starts early, progresses “stealthily,” and can present “out of the blue in devastating ways.”

The AHA published another study on Thursday revealing one million hospitalizations, showing that heart attack deaths are climbing among adults below the age of 55.

The more alarming finding, according to Klodas, is that young women were found more likely to die after their first heart attack than men of the same age.

DOCTOR SHARES 3 SIMPLE CHANGES TO STAY HEALTHY AND INDEPENDENT AS YOU AGE

“This is all especially tragic since heart disease is almost entirely preventable,” she said. “The earlier you start, the better.”

Children can show early evidence of plaque deposition in their arteries, which can be reversed through lifestyle changes if “undertaken early enough and aggressively enough,” according to the expert.

Moving more is one part of protecting a healthy heart, according to experts. (iStock)

Klodas suggested that rising heart conditions are associated with traditional risk factors, like smoking, high blood pressure, high cholesterol, diabetes, obesity and a sedentary lifestyle.

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Doctors are also seeing higher rates of preeclampsia, or high blood pressure during pregnancy, as well as gestational diabetes. Klodas noted that these are sex-specific risk factors that don’t typically contribute to complications until after menopause.

The best way to protect a healthy heart is to “do the basics,” Klodas recommended, including the following lifestyle habits.

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Klodas especially emphasized making improvements to diet, as the food people eat affects “every single risk factor that the AHA’s report highlights.”

“High blood pressure, high blood sugar, high cholesterol, excess weight – these are all conditions that are driven in part or in whole by food,” she said. “We eat multiple times every single day, which means what we eat has profound cumulative effects over time.”

“Even a small improvement in dietary intake, when maintained, can have a massive positive impact on health,” a doctor said. (iStock)

“Even a small improvement in dietary intake, when maintained, can have a massive positive impact on health.”

The doctor also recommends changing out a few snacks per day for healthier choices, which has been proven to “yield medication-level cholesterol reductions” in a month.

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“Keep up that small change and, over the course of a year, you could also lose 20 pounds and reduce your sodium intake enough to avoid blood pressure-lowering medications,” Klodas added.

“Women should not view the AHA report as inevitable. We have power over our health destinies. We just need to use it.”

Angelica Stabile is a lifestyle reporter for Fox News Digital.

Health

Vanessa Williams, 62, Opens up About Weight Loss and HRT After Menopause

Published

12 hours ago

February 26, 2026

Press Room

Vanessa Williams, 62, Opens up About Weight Loss and HRT After Menopause

Vanessa Williams Opens up About Weight Loss and HRT | Woman’s World

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Health

Common vision issue linked to type of lighting used in Americans’ homes

Published

13 hours ago

February 26, 2026

Press Room

Common vision issue linked to type of lighting used in Americans’ homes

NEWYou can now listen to Fox News articles!

Nearsightedness (myopia) is skyrocketing globally, with nearly half of the world’s population expected to be myopic by 2050, according to the World Health Organization.

Heavy use of smartphones and other devices is associated with an 80% higher risk of myopia when combined with excessive computer use, but a new study suggests that dim indoor lighting could also be a factor.

For years, scientists have been puzzled by the different ways myopia is triggered. In lab settings, it can be induced by blurring vision or using different lenses. Conversely, it can be slowed by something as simple as spending time outdoors, research suggests.

Nearsightedness occurs when the eyeball grows too long from front to back, according to the American Optometric Association (AOA). This physical elongation causes light to focus in front of the retina rather than directly on it, making distant objects appear blurry.

The study suggests that myopia isn’t caused by the digital devices themselves, but by the low-light environments where they are typically used. (iStock)

Researchers at the State University of New York (SUNY) College of Optometry identified a potential specific trigger for this growth. When someone looks at a phone or a book up close, the pupil naturally constricts.

COMMON VISION ISSUE COULD LEAD TO MISSED CANCER WARNING, STUDY FINDS

“In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina,” Urusha Maharjan, a SUNY Optometry doctoral student who conducted the study, said in a press release.

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“When people focus on close objects indoors, such as phones, tablets or books, the pupil can also constrict — not because of brightness, but to sharpen the image,” she went on. “In dim lighting, this combination may significantly reduce retinal illumination.”

High-intensity natural light prevents myopia because it provides enough retinal stimulation to override the “stop growing” signal, even when pupils are constricted. (iStock)

The hypothesis suggests that when the retina is deprived of light during extended close-up work, it sends a signal for the eye to grow.

In a dim environment, the narrowed pupil allows so little light through that the retinal activity isn’t strong enough to signal the eye to stop growing, the researchers found.

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In contrast, being outdoors provides light levels much brighter than indoors. This ensures that even when the pupil narrows to focus on a nearby object, the retina still receives a strong signal, maintaining healthy eye development.

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The team noted some limitations of the study, including the small subject group and the inability to directly measure internal lens changes, as the bright backgrounds used to mimic the outdoors made pupils too small for standard equipment.

Researchers believe that increasing indoor brightness during close-up work could be a simple, testable way to slow the global nearsightedness epidemic. (iStock)

“This is not a final answer,” Jose-Manuel Alonso, MD, PhD, SUNY distinguished professor and senior author of the study, said in the release.

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“But the study offers a testable hypothesis that reframes how visual habits, lighting and eye focusing interact.”

The study was published in the journal Cell Reports.

Khloe Quill is a lifestyle production assistant with Fox News Digital. She and the lifestyle team cover a range of story topics including food and drink, travel, and health.