As the temperature and humidity outside rise, what’s happening inside the human body can become a life-or-death battle decided by just a few degrees.
Researchers say the risk of illness and death from extreme heat outside is much lower than experts previously thought. Researchers put people in heat boxes to see what effect it had on them.
As much of the United States, Mexico, India and the Middle East suffer from intense heat waves caused by climate change, several doctors, physiologists and other experts told The Associated Press what effects such heat has on the human body.
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Heat waves can raise your body temperature
The body’s resting temperature is normally around 98.6 degrees Fahrenheit.
It’s just 7 degrees away from causing a catastrophe known as heat stroke, said Oli Jay, a professor of heat and health at the University of Sydney in Australia, where he runs the Thermoergonomics Laboratory.
Dr. Neil Gandhi, director of emergency medicine at Houston Methodist Hospital, said, during heat waves Anyone who comes in with a fever of 102 or higher and no obvious source of infection should be seen for heat exhaustion or the more severe heatstroke.
A man pours cool water over his head on a hot summer day at the Mediterranean Sea in Beirut, Lebanon, July 16, 2023. As temperatures and humidity rise, what happens inside the human body can become a life-or-death battle decided by a few degrees. (AP Photo/Hassan Ammar, File)
“We often see core temperatures over 104, 105 degrees in some of the heat waves,” Gandhi said. Patients with temperatures that are one or three degrees higher are at much higher risk of death, he said.
How does heat kill?
Heat kills in three main ways, Jay said. The first suspicion is of heatstroke — Severe increase in body temperature leading to organ failure.
Jay said that when the body’s internal temperature rises too high, the body diverts blood flow to the skin to cool down. But this diverts blood and oxygen away from the stomach and intestines, and toxins that would normally be confined to the intestinal region begin to leak into the blood circulation.
“This triggers a number of side effects, including clotting in the body, multiple organ failure, and eventually death,” Jay said.
But Jay said the biggest harm from heat is the strain it puts on the heart, especially for people with heart disease.
It starts again when blood rushes to the skin to help expel core heat. This causes blood pressure to drop. The heart responds by trying to pump more blood to keep you from fainting.
“You’re making the heart work a lot more than it normally does,” Jay said. For a person with heart disease, “it’s like running behind a bus with a hamstring problem. Something’s going to happen.”
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The third main cause is dangerous dehydration. Jay said that when people sweat, they lose fluids, which puts a lot of pressure on the kidneys.
Gandhi, of Houston, said many people don’t realize the danger they’re in.
Dehydration can progress to shock, whereby a lack of blood, oxygen and nutrients causes organs to shut down, leading to seizures and death, said Dr. Renee Salas, a professor of public health at Harvard University and an emergency room physician at Massachusetts General Hospital.
“Dehydration can be very dangerous, even life-threatening, for anyone if the condition becomes severe enough — but it’s especially dangerous for people with underlying medical conditions and those taking certain medications,” Salas said.
Dehydration also reduces blood flow and increases the risk of cardiovascular problems, Jay said.
Intense heat could ‘fry’ your brain
Many doctors say that heat also affects the brain. This can cause a person to become confused or have trouble thinking.
“If you get confused, heat exhaustion is the first symptom,” said Chris Eby, a public health and climate professor at the University of Washington. He added that it’s hardly helpful as a symptom because a person suffering from heat exhaustion is unlikely to recognize it. And it becomes a bigger problem as you age.
A classic definition of heat stroke is a body temperature of 104 degrees accompanied by cognitive impairment, said W. Larry Kenney, a physiology professor at Pennsylvania State University.
Heat and humidity are a dangerous pair
Some scientists use a more complex outdoor temperature measurement called the wet bulb globe temperature, takes into account humiditysolar radiation and wind. In the past, it was believed that a wet-bulb reading of 95 Fahrenheit was the point when the body began to have trouble, said Kenny, who also runs a hot box lab and has conducted about 600 tests with volunteers.
His tests show the wet-bulb danger point is closer to 87. That’s the figure he said is starting to show up in the Middle East.
And that’s just for young healthy people. The danger point for older people is a wet bulb temperature of 82, he said.
“Humid heat waves kill a lot more people than dry heat waves,” Kenny said.
When Kenney tested young and old people in dry heat, the younger volunteers could work up to 125.6 degrees, while the older ones stopped at 109.4 degrees. With high or moderate humidity, people couldn’t work at nearly as high temperatures, he said.
“Humidity affects the ability of sweat to evaporate,” Jay said.
How to cool down heat exhaustion patients?
Salas said heatstroke is an emergency and medical personnel attempt to cool the victim within 30 minutes.
the best way: Immersion in cold water“Basically, you put them in a bucket of water,” Salas said.
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But these are not always available. So in emergency rooms, patients are given cold fluids intravenously, are sprayed with mist, have ice packs placed on the armpits and groin, and are laid on a cold mat with cold water running through it.
Sometimes it doesn’t work.
“We call it the silent killer because it’s not a visually dramatic phenomenon,” said Jay. “It’s insidious. It’s hidden.”
