How does extreme heat affect the body and what can you do about it?

A dangerous heat wave is threatening large parts of the southwestern US, with millions of people under a heat advisory for the second week in a row. Temperatures were expected to rise on Tuesday 102F in Sacramento, California, and on Wednesday until 111F in Phoenix, Ariz. The sweltering heat is expected to reach the east coast on Friday.

Health experts and climate scientists described the effects of extreme heat on the human body, which populations are most at risk, and ways to mitigate them.

What is heat stress and what causes it?

It occurs when the body experiences a buildup of heat, at a level that exceeds what it can release. “The human body has an amazing ability to cool down through evaporation of sweat,” says Uwe Reischl, a professor in the school of public health and public health at Boise State University. But even if the body produces sweat, evaporation may be limited due to the humidity in the air.

Another factor that causes body temperature to rise is when a person wears clothing that prevents sweat from being released from the skin. And when the body doesn’t have enough water, it becomes so dehydrated that it can no longer produce sweat.

How does this relate to the ongoing heat dome phenomenon?

Warm air can hold more moisture than cold air. “So the warmer the heat dome, the higher the humidity,” says Reisl. Urban environments with many buildings, paved roads and parking lots increase the risk of heat stress because they absorb (and release) heat from the sun all day long.

What are some signs of heat stress?

“Heat stress is a spectrum,” says Kristie Ebi, a professor of environmental and occupational health at the University of Washington. Symptoms can range from small, reddish blisters on the hands to fainting. In extreme cases, if the body temperature rises above 39 degrees Celsius, it can result in heat stroke, which can cause the brain and other internal organs to swell, which can be fatal.

Who is the most suffer from heat stress?

Children, the elderly and pregnant people are among the most vulnerable to heat stress. “Athletes and outdoor workers can be at much greater risk of heat stress,” says Ebi. The more people move or work, the more heat their bodies have to dissipate. These conditions are more difficult for people such as farm workers, who need to be protected from physical or chemical hazards, such as pesticides. They must wear protective clothing, which can hinder their body’s ability to evaporate sweat.

How do human bodies recover from heat stress?

“When we are exposed to high temperatures, we need time for our bodies to cool down, and this normally happens at night,” says Ebi. (But since 1970, nighttime summer temperatures have increased by Average 3Fwhich means people get less reprieve at night.)

“In addition to resting, the body needs to rehydrate,” Reischl said, adding that people should drink more water than they normally would.

What can people do to reduce heat stress?

Avoid strenuous outdoor activities, drink fluids, stay away from the sun and spend more time in air-conditioned places such as cooling centers.

What are some ways to stay cool without air conditioning?

Putting your feet in cold water, putting cool towels around your neck, sitting in front of an electric fan and sprinkling water on yourself are effective ways to cool down. Such as pulling down the sun blinds in the house during the day and opening the windows at night.