Heat related illnesses

What are Heat-Related Illnesses?

Prolonged or intense exposure to hot temperatures can cause heat-related illnesses such as heat exhaustion, heat cramps, and heat stroke (also known as sun stroke). As your body works to cool itself under extreme or prolonged heat, blood rushes to the surface of your skin. As a result, less blood reaches your brain, muscles, and other organs. This can interfere with both your physical strength and your mental capacity, leading, in some cases, to serious danger

With prompt treatment, most people recover completely from heat-related illness. However, heat stroke can be deadly if not properly managed.

What Causes Heat-Related Illnesses?

• Heat-related illness can strike anyone.
• But chronic alcoholics, the elderly, the young, the obese, and individuals whose immune systems may be compromised are at greater risk, as are individuals taking certain drugs, such as antihistamines, antipsychotic medications, and cocaine.
• High humidity also increases the risk of heat illness because it interferes with the evaporation of sweat, your body's way of cooling itself.
• Children and teens adjust more slowly than adults do to changes in environmental heat. They also produce more heat with activity than adults, and sweat less. Sweating is one of the ways the body cools itself. Children and teens often don't think to rest when having fun and may not drink enough fluids when playing, exercising, or participating in sports.
  • Children and teens with chronic health problems, or those who take certain medicines, may be more susceptible to heat-related illnesses. Children and teens who are overweight or wear heavy clothing during exertion, such as marching band or football uniforms, are also more susceptible.
• The reasons that people have heat related illnesses can be broken into two main categories:
  • Exercise-associated heat exhaustion or heat stroke, such as exerting in a hot environment
  • Non-exertional classic heat stroke, such as being trapped in a hot environment (i.e. car/ vehicle)
• Heat exhaustion, heat cramps, and heat stroke all occur when your body cannot cool itself adequately. But each is slightly different.
  • Heat exhaustion occurs when the body loses large amounts of water and salt through excessive sweating, particularly through hard physical labor or exercise. This loss of essential fluids can disturb circulation and interfere with brain function. Individuals who have heart, lung, or kidney problems or are on low-sodium diets may be particularly susceptible to heat exhaustion.
    • Symptoms are nonspecific: any combination of isolated muscle or generalized weakness, fatigue, dizziness, headache, occasional syncope, nausea, vomiting, diarrhea, hyperventilation, tachycardia, orthostatic hypotension, vertigo, chills, visual disturbances, cutaneous flushing. Core body temperature is usually between 38.0-40.0 C (98.6-104 F). Mental status is normal
    • Contact your doctor if signs or symptoms worsen or if they don't improve within one hour.
  • Heat cramps can strike when the body loses excessive amounts of fluids and salt. This deficiency, accompanied by the loss of other essential nutrients such as potassium and magnesium, typically occurs during heavy exertion.
    • Workers most prone to heat exhaustion are those that are elderly, have high blood pressure, and those working in a hot environment.
    • Heat cramps may also be a symptom of heat exhaustion.
  • Heat stroke, the most serious of the heat-related illnesses.
    • Heat stroke is a medical emergency that may result in death! Call 911 immediately.
    • It is defined as hyperthermia with a body temperature greater than 40.6 °C (105.1 °F) because of environmental heat exposure with lack of thermoregulation. This is distinct from a fever, where there is a physiological increase in the temperature set point of the body.
    • It occurs when the body suffers from long, intense exposure to heat and loses its ability to cool itself. In prolonged, extreme heat, the part of the brain that normally regulates body temperature malfunctions. There is a decrease in the body's ability to sweat and, therefore, cool down. Those who have certain medical conditions that decrease the body's ability to sweat -- such as scleroderma or cystic fibrosis -- may be at greater risk of developing heat stroke.
    • When heat stroke occurs, the body temperature can rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not given.
    • Symptoms may include disorientation, muscle twitching, ataxia, anxiety with tachycardia (rapid heart beat), hyperventilation (rapid breathing), dyspnea (shortness of breath), anhidrosis (inability to sweat normally)
    • The term "stroke" in "heat stroke" is a misnomer in that it does not involve a blockage or hemorrhage of blood flow to the brain.
  • Rhabdomyolysis
    • Rhabdomyolysis is a medical condition associated with heat stress and prolonged physical exertion, resulting in the rapid breakdown, rupture, and death of muscle. When muscle tissue dies, electrolytes and large proteins are released into the bloodstream that can cause irregular heart rhythms and seizures, and damage the kidneys.

Activities that carry the greatest risk for hyperthermia

• Activities: Football, soccer, rugby, cricket, marathon or long-distance running, using saunas and hot tubs, hiking, biking
• Jobs/types of work: the military, construction, manufacturing, emergency responders (firefighters, police, 911 medical teams), agriculture, forestry, surveyors, conservationists and field biologists, park staff & wildlife officials

Statistics & Mortality

• Seventeen of the hottest years on record occurred this century.
• In June 2015, Pakistan experienced a heat wave so severe that more than 1,229 people died. A month earlier, temperatures in parts of India climbed up to 113 °F, killing at least 2,500 people.
• A 2014 report by the Centers for Disease Control estimated that 666 people die every year in the U.S. from heat-related causes. In some extreme cases, such as the 2003 heatwave in Europe, 70,000 deaths were attributed to the heat.
• A 1996 heatwave in Chicago, a city that doesn't regularly deal with severe swells in temperature, killed at least 700 people.
• Last year, 108 people died from extreme heat, compared to just 30 who died from cold, according to statistics on weather-related fatalities released by the National Oceanic and Atmospheric Administration. (From: The New York Times – Heat Wave to Hit Two-Thirds of the U.S Here’s What to Expect. By Farah Stockman. 17 Jul 2019)
• In June 2018, dozens of people were killed across the U.S. and in Canada—including 28 people just in Montreal. Japan recorded an all-time high of 106 in 2018 as a total of 96 people were killed across the country. In Seoul, 29 people died during a two-week stretch of 95-degree days. In 2003, during a heat wave that swept Europe, 35,000 people were estimated to have died at the time. Now scientists believe the death toll is closer to 70,000. (From: Curbed – Our cities are getting hotter—and it’s killing people. By Alissa Walker. 21 Jun 2019)
• Heat Stroke—a catastrophic, life-threatening medical emergency. Morbidity is high (17-70%)

Notables who died from heat-related illness/hyperthermia

1. Ranker – Famous People who died of Hyperthermia (8 people listed)

• Mark Leduc (1962-2009) – Canadian boxer; Wikipedia – Mark Leduc He had collapsed in the sauna of St. Mark's Spa and doctors suggested that his death may have resulted from heat stroke.
• Nathanael Greene (1742-1786) – Major General in Continental Army in American Revolutionary War; died suddenly of sunstroke in 1786.
• Evan Tanner (1971-2008) – American martial arts fighter; Wikipedia – Evan Tanner official cause of death was cited as heat exposure.
• Carl Scarborough (1914-1953) – American racecar driver; Wikipedia – Carl Scarborough
• Korey Stringer (1974-2001) American football player; Wikipedia – Korey Stringer He suffered from heat stroke on the second day of the Vikings 2001 preseason training camp, and died as a result of complications on August 1, 2001

Resources & additional reading

• WebMD - Understanding Heat-Related illness—the Basics
• CDC – Warning signs & symptoms of Heat- Related illness (Has chart with “What to look for” & “What to do”)
• CDC / NIOSH – Heat Stress – Heat Related Illness
• OSHA – Heat-related Illnesses & First Aid (Has chart with symptoms & first aid)
• University of Rochester Medical Center – Heat-Related Illnesses (Heat Cramps, Heat Exhaustion, Heat Stroke) (Focuses on children/teens & has chart with conditions, symptoms & first aid/treatment)
• Scientific American – Killer Heat Grows Hotter around the World. By: Gayathri Vaidyanathan, Climate Wire on 6 Aug 2015
• Popular Science – As summers get hotter, death tolls will rise. By: Dana G Smith, 28 Aug 2018
• Medical News Today – What should you know about hyperthermia. By: Jennifer Huizen. 5 Dec 2017
• Mayo Clinic – Heat exhaustion
• TN Dept of Health – Heat-Related Illness
• Pediatrics Clerkship – Heat Related Illnesses
• ATA Comp Fund – Heat-Related Illness- Beat the Heat

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