Extreme Heat Survival Guide: Why The Body Fails
Between 2000–2019 studies show approximately 489,000 heat-related deaths occur worldwide each year, with 45% of these in Asia and 36% in Europe (2). In Europe alone in the summer of 2022, an estimated 61,672 heat-related excess deaths occurred (3). High intensity heatwave events can bring high acute mortality; in 2003, 70,000 people in Europe died as a result of the June–August event. In 2010, 56,000 excess deaths occurred during a 44–day heatwave in the Russian Federation. Heat and Health - WHO May, 2024.
How Our Body Cools
The human body’s thermostatic process is how it maintains a stable internal temperature (homeostasis), typically around 98.6°F or 37°C. This regulation is controlled by the hypothalamus in the brain, which acts like a thermostat, adjusting body temperature in response to internal and external conditions.
The body essentially has two ways to cool itself down and "thermoregulate" body temperatures. Firstly, the body "vasodilates" or simply transfers the heat from the core body zones by dilating the blood vessels, redistribute the flow of blood from the muscles and transfer the heat to the skin and produce sweat. High core body temperatures cause high rapid heartbeats, increased blood pressure and heavy sweating to cool the body down quickly. Secondly, the evaporation of the body perspiration or sweat creates the cooling effect. The byproduct of skeletal muscle contraction is heat. The harder the body works, the more body heat it has to dissipate, consequently the harder the body works to thermoregulate, the harder the heart has to work.
Body Cooling System Overload - "Danger Zone"
As long as the body is constantly rehydrated and perspiration is evaporated quickly, the thermoregulatory systems will be able to transfer the heat from the muscles to keep the body's core within the normal temperature range to avoid heat stress. However in high heat, if fluids are not replaced from the profuse sweating, the loss of water and electrolytes dehydrate the body. Dehydration triggers the surface blood vessels to constrict limiting sweat production to keep the body functioning by conserving blood volume, causing core body temperatures to rise. Heart rate slows, blood volume and pressure drops as it becomes harder for the heart to circulate oxygen, causing weakness, headache, nausea and fainting.
Body Cooling System Failure or Hyperthermia - "Life Threatening"
Under extreme heat stress, the breakdown in the body's cooling process creates increased cardiac demands, dehydration and pulmonary stress. The situation becomes life threatening, especially if the body's core temperature rises above 104°F or 40°C, the skin becomes hot and dry, the person experiences confusion, seizures, and loses consciousness. The first cells affected by core body temperatures equal or greater than 104°F or 40°C are: neurons, hepatocytes (liver cells) and vascular endothelial cells (the inner lining of all blood vessels). In addition to the brain, heart, liver, kidneys and central nervous system, all body organs will be injured by hyperthermia.
Surviving Hyperthermia - "Time is Critical"
The estimated time for heat stress to lead to death is 30 minutes from the onset. Sara Kendall of BC Emergency Health Services: heat stroke has a remarkably high mortality rate, between 62.6% of heat stroke patients who arrive to hospital do not survive and the single greatest contributor to patient morbidity and mortality is the duration of the elevated core body temperature. According to a study on the short-term and long-term outcomes of heatstroke following the 2003 heat wave in Lyon, France. Arch Intern Med. 2007, Regarding heat stroke, 28-day and 2-year mortality rates have been reported to be 58% and 71%, respectively. The importance of initiating cooling on-scene cannot be overstated. All heat illness patients should receive immediate cooling on-scene and during transport, regardless of proximity of higher level of care.
Long-Term Effects of Repeated Heat Stress
Kidney damage (due to dehydration and breakdown of muscle tissue).
Heart strain (as the heart works harder to circulate less blood).
Cognitive issues (confusion, memory problems).
Heat intolerance (reduced ability to handle high temperatures in the future).
Valuable Lessons:
1) Heat Stress is a silent, progressive illness that within minutes quickly develop into a life-threatening situation. Heat Stress can only be measured by the temperature of your body's core. Although athletes can train their bodies to perform at extreme temperatures 104°F-105°F to be heat tolerant, it is done so with careful preparation, acclimation, monitoring and training. It often takes two to three weeks to become acclimated to a hot environment, especially coming back from a vacation and going directly to an extreme heat environment. If you have had heat illness or a pre-existing health condition or above 60 years old consider yourself a very high heat risk and it would be wise to take every precaution when working in the heat.
2) Public Air Temperature Forecasts are indicators only and not the actual temperature at the specific location. Temperatures in 80°F's are high enough to result in a Heat Index value of 90F and cause heatstroke and death. Elevated core body temperatures are a result of not only local temperatures, relative humidity, but is also influenced by solar heat, surrounding radiant heat, equipment, surrounding machinery, physical exertion, heavy work loads, heavy clothing, protective wear, the ability to cool and preventative cooling techniques.
3) Be aware of Heat Illness symptoms, do not take the symptoms lightly, when in doubt take the necessary precautions and don't take chances. Stick to "that age-old adage" - "An ounce of Prevention is worth a pound of Cure". Core Body Temperatures are the most important measurement to determine heat stress and targeting the core body zones are the best way to lower core temperatures fast.
4) When experiencing any heat-related symptoms, act fast, seek immediate medical assistance and do not be alone. Find a buddy or call a friend. Move to a shaded cool location and cool down by targeting the core body zones.
5) Due to the inability to assess the real effects of heat stress and the long term effects of heat illness, if you have had any symptoms of heat stress or heat illness there is a high chance you are a high risk and to get closer and extended term medical monitoring.
Heat Protection Tips:
1) Learn the signs and symptoms of Heat Stress, as it is often overlooked or ignored by the victim
2) Have adequate hydration and electrolytes available at all times and schedule regular hydration breaks, use alarms or reminders.
3) Carry and have cold packs or ice storage packs for available use at all times. Schedule period cooling sessions with cold therapy.
4) If possible adjust the work schedule and assign heavier work on cooler days or during the cooler part of the day. Check weather alerts. OSHA-NIOSH heat safety tool App
5) Reduce the workload and physical exertion on hot days to reduce physical labor.
6) Wear light-colored, loose clothing where possible
7) Try to stay out of direct sunlight as much as possible and wear sunscreen
8) Schedule frequent breaks to cool down in a shaded cool area to avoid overheating
9) It often takes two to three weeks to become acclimated to a hot environment, especially coming back from a vacation and going directly to an extreme heat environment
10) If you take any kind of medication, diet pills, sedatives, channel blockers, diuretics, antidepressants, or tranquilizers check with your doctor
11) Avoid alcohol, caffeinated drinks and heavy meals. Foods (like proteins) increase metabolic heat production and also increase water loss.
12) Do not sit or stay in a hot vehicle, building or enclosed environment without the proper air-conditioning.
13) If working alone, use a buddy system, stay in touch or have someone check on you.
14) Aside from full body cooling, targeted core body cooling is the best way to treat heat stress, until core temperature drops to 38.3°–39°C. In the event of heat stress, time is critical in cooling the body core. Check out our revolutionary the Krazy Kool TechnologyTM System and the science behind our products -"Science of Kool".
