Dr. Greene's Answer
Normal body cooling happens by sweating, but sometimes this natural process isn’t enough when temperatures are extreme (especially combined with exercise or improper clothing).
Between 2000 and 2019, according to a 2021 study in The Lancet, more people died from extreme heat each year, on average, than from all other natural disasters combined. This includes earthquakes, floods, droughts, hurricanes, tidal waves, and wildfires.
At the time, 19 of the 20 hottest years recorded since 1880 had occurred after 2000.
And extreme heat is becoming even more common. The most recorded deaths from natural disaster in 2022 were from the heat wave across Europe. And the heatwave in 2022 in China was called the most severe ever recorded in the world by New Scientist, combining extreme heat and extreme length over an extremely large area – nothing in world climatic history comparable.
And NASA reports that July 2023 was the hottest month on record.
It’s time to become familiar with heat-related illnesses: how to prevent them, recognize them, and treat them.
Most heat-related illnesses occur in the summer. Groups who are most at risk for heat injury include the young (0 to 4 years old) and elderly, outdoor workers, those with mental illness or chronic diseases, and even young healthy athletes if they are participating in strenuous physical activity in high outdoor temperatures. And, significantly, those who don’t have the wherewithal to get where it is cooler.
Children’s skin can be quite sensitive to heat. Nursing mom’s often discover this, especially in the summertime, when their baby’s face turns red where it is against the mother’s skin. This redness comes from blood vessels in the area dilating to cool the skin down. Cooling the skin usually makes the rash disappear within hours, or even sooner. Prickly heat (miliaria rubra) is a type of heat rash that lasts.
Heat cramps are the most common form of heat-related ailment. They most often occur when exercising in a warm environment, as sweating depletes the body of salt and water. This lowered salt level can lead to muscles cramping. The calf or hamstring muscles are most commonly affected and respond to gentle stretching and rehydration – especially with an electrolyte solution.
Heat syncope is fainting due to heat/dehydration. This is caused by dilation of the blood vessels to radiate heat. During heat syncope, the blood pressure is low and heart rate is elevated. This condition responds to cooling (like a sponge bath), lying down with feet up, and drinking fluids.
Heat edema is swelling of the hands or feet from heat. People sometimes get this condition when initially exposed to hot weather, and it usually goes away as the person adjusts to the heat.
Heat tetany is tingling (especially of the wrists). Hyperventilation in hot weather can cause heat tetany. The best way to treat this condition is to remove the person from the hot environment and work to slow their breathing.
Heat exhaustion usually entails a temperature of 101 to 104, headache, nausea, vomiting, dizziness, and fainting. Heat exhaustion may occur gradually, over the course of several days of exposure to high temperatures. It is important to recognize and treat heat exhaustion immediately. Treatment includes cooling, fans, taking off extra layers of clothing, drinking liquids, and applying ice over the groin and armpits). People typically respond well, but prompt treatment is necessary in order to prevent the condition from progressing to heat stroke where treatment may no longer be effective.
Heat stroke is very serious. A person’s temperature rises over 104 degrees, and he or she has an altered mental status. There are two types of heat stroke — exertional, with profuse sweating, and classic, in which the skin is hot and dry. Classic heat stroke builds up over days, and is most common in infants and in the elderly. It is a true emergency. In the elderly population, up to 50% of those with heat stroke may die. Exertional heat stroke has a much better prognosis because it generally affects the young, healthy athlete and the diagnosis is often prompt, leading to a mortality of less than 5%. Both types of heat stroke are true medical emergencies and need to be recognized and treated immediately. .
It is very important to take measures to protect yourself and others against these heat-related illnesses. A few tips for prevention include staying out of direct sun during very hot days, avoiding strenuous physical activity during the hottest part of the day, wearing light colored clothing, wearing sunscreen and avoiding sunburns, staying hydrated (drink before you are thirsty!), and recognizing the first signs of any heat-related illness.
Resources and References
CDC Extreme Heat Information.
EpsteinY, et al. Heatstroke. The New England Journal of Medicine 2019; 380(25): 2449–2459.
Global, Regional and National Burden of Mortality Associated with Non-Optimal Ambient Temperatures from 2000 to 2019. The Lancet Planetary Health; July 2021 5(7): e415-425
Our World in Data: Natural Disasters
Heatwave in China is the Most Severe Ever Recorded in the World. New Scientist; 23 August 2022
NASA Clocks July 2023 as the Hottest Month on Record. NASA Press Release; 14 August 2023