• With heat waves hitting Europe and the United States, health experts are warning people to be careful when exercising or working in the sun.
• Too much exposure to the heat can cause serious health problems, including heat stroke.
• Symptoms of heat-related illnesses are excessive sweating, light-headedness, and rapid breathing.
• If you exercise in the heat be sure to hydrate properly and try to work out before 10 a.m. or after 6 p.m.
• If you work in the sun, wear loose-fitting, light-colored clothes in addition to drinking plenty of water.

It’s official. The Earth is hotter than ever.

Last month, the planet experienced its warmest June in recorded history.

Europe was one of the focal points of the hot weather.

France recorded its highest temperature ever last Friday with the mercury rising to 114°F (46°C) in some parts of the country.

Among those dealing with this hot weather are the players of the Women’s World Cup in France, who have been training and playing in temperatures hovering around 90°F (32°C) this week.

Temperatures were also heating up across the United States with heat waves as far north as Alaska setting records.

Scientists say climate change is likely the reason behind the heat waves, and health experts are urging people to be mindful of the risks of heat-related illness. 

“Generally, caution should be taken if the heat index is over 77 degrees (Fahrenheit). Above 82 degrees is considered ‘extreme caution’ — heat-related illness is possible with long exposure. Over 85 is dangerous — heat illness is likely and heat stroke is possible. Eighty-nine and above gives a high risk of heat stroke,” Dr. Sterling Ransone, a practicing family physician in Deltaville, Virginia, told Healthline. 

More than 600 people Trusted Source in the United States die due to extreme heat every year.

Heat-related illnesses such as heat stroke occur when the body struggles to cool itself.

The human body uses sweat as a means of cooling off, but in extreme heat, sweating can’t always cool the body down. This can be particularly problematic in times of increased humidity. 

“When humidity is very high, our sweat cannot evaporate and drips off our body. Sweat must evaporate to be effective for releasing heat. If it drips off our body, then it is wasteful sweat. More humid conditions present this challenge. When the temperature is above 80 degrees and humidity is greater than 75 percent, the risk for heat injury is high,” Micah Zuhl, PhD, an assistant professor in the department of health, exercise and sport sciences at the University of New Mexico, told Healthline. 

The risks of heat-related illness

Officials at the Centers for Disease Control and Prevention (CDC) advise that older people, very young children, those with mental illness, and those with chronic health problems are at greatest risk for heat-related illness. 

However, even healthy young people can be impacted if they aren’t careful. 

Experts say it is OK to exercise in the heat, but they caution that without proper precautions, overheating is a possibility. 

“When we exercise, we use our muscles and generate heat,” Ransone explained. “We first rid ourselves of excess heat by dilating our blood vessels to radiate it into the environment. However, the main method of dealing with the excess heat is that we perspire. Frequently in hot weather, we have already dilated our vessels and started sweating due to the environmental conditions.”

This is particularly true when humidity is high.

“High humidity can prevent any perspiration from evaporating easily,” said Ransone. “These conditions do not leave us much margin to cool off naturally should we begin exercising, making it much easier for us to overheat and become ill.”

Symptoms of heat-related illnesses

Experts advise that people outside in hot weather need to be aware of any symptoms of heat-related illness.

“Symptoms that can occur… include excessive sweating, nausea, light-headedness, extreme thirst, very rapid breathing, and higher than normal heart rate. If you recognize these then you should stop exercise and immediately find a comfortable climate,” Zuhl said. 

Early symptoms of heat-related illness, if ignored, can develop into more serious heat stroke.

When a person is suffering from heat stroke, their body temperature can rise to 104°F (40°C) or more. Symptoms include confusion, slurred speech, profuse sweating or hot, dry skin, loss of consciousness, seizures, and a high body temperature.

“These symptoms are considered emergencies and could lead to brain damage or death. You should call 911 immediately,” Ransone said. 

How to exercise in the heat

Ransone advises those who wish to exercise in the heat to always check the heat index before venturing out.

If the temperature is above 89°F (32°F), he advises using caution before going outside.

It is also helpful to exercise outside peak sun times such as before 10 a.m. or after 6 p.m. 

“Hydrate before, during, and after any exercise session. Drink mainly water, occasionally a sports drink, and avoid caffeine and alcohol,” he said. “Wear sunscreen and protective clothing, take frequent scheduled rest and water breaks, and remember that many medications can place your body in danger of heat-related problems. Speak with your family doctor to see if any of your medications could put you at risk.” 

Working in the heat

For those who have to work outdoors in the heat this summer, doctors advise similar precautions.

Wear lightweight, lighter-colored, loose-fitting clothes. Also travel to and from work in cooler periods of the day and take extra precautions if there is no breeze and high humidity. 

Above all, whether exercising or working in the heat, it is crucial to stay hydrated. 

“Be careful to avoid dehydration in warm weather. This can predispose to heat-related illnesses. Consume adequate volumes of fluid; one’s urine should not be concentrated or dark as this is a sign of dehydration. As we tell our Scouts: Drink until your pee is clear,” Ransone said. 

“Get outdoors and enjoy nature but be thoughtful,” he added.