Taking the stress out of heat

EMS reponding to heat stroke

When the ambient temperature gets high enough to overcome the body’s ability to dissipate heat, heat-related illnesses occur. Older adults, young children, and those with chronic medical conditions are particularly susceptible to heat illnesses and have higher heat-related mortality.

A partial list of chronic medical conditions that increase risk and mortality include:

  • Cardiovascular diseases
  • Diseases of the respiratory system
  • Endocrine, nutritional and metabolic disorders
  • Diseases of the digestive system
  • Diseases of the nervous system, infections immune disorders, and neoplasms

The CDC reported that the number of heat-related deaths is underestimated. Part of the attempt to improve the reliability of the statistics included developing a definition of heat-related death. It is defined as “A death in which exposure to high ambient temperatures either caused the death or contributed to it substantially. The decedent had a body temperature at the time of collapse greater than 105 degrees F (40.6 degrees C), and the decedent had a history of exposure to high ambient temperature and other causes of hyperthermia could be reasonably excluded.” The underlying cause of death “defines as the disease or injury that initiate the chain of events that lead directly and inevitably to death. Contributing conditions, or factors, are defined as disease, injuries or complications that directly caused the death.”

Preventing heat stress

We all have been trained to recognize and treat heat cramps, heat exhaustion, heat syncope, and heat stroke. When we see them in patients, we recognize them immediately and treat them effectively. Are we equally astute in recognizing these disorders in ourselves and co-workers? NIOSH has a Fast Facts Advisory entitled “Protecting Yourself from Heat Stress”. It is recommended that we avoid heavy exertion, extreme heat, sun exposure and high humidity. We should also gradually build up to heavy work and schedule it during the coolest part of the day.

Take precautions, wear apparel for outdoor work that is sun-protective, light in weight and color, loose fitting, comfortable, and capable of wicking away sweat. There are fabric additive like Sun Guard, which increases the ultraviolet protection factor (UPF) of your clothing. Don’t forget sunscreen. The FDA recommends broad spectrum sunscreens with SPF values of 15 or higher. Sunscreen should be applied 20 minutes before you’re in the sun and re-applied every two hours. When selecting your sunglass check that they block at least 99% of UVA and UVB radiation or meet the ANSI Z80.3 blocking requirements. In addition to long-term effects like cataracts exposure to the sun without proper eye protection can lead to eye strain.

Do you recognize the importance of hydration? The body is about 66% water, muscles are up to 75% water, and lungs are about 90% water. Think about how dehydration causes the symptoms seen in various heat-related illnesses. We know that water is the best choice for fluid replacement, but remember for prolonged or heavy sweating we need to also replace electrolytes to avoid dilutional hyponatremia. Don’t forget about eating properly by including fresh fruits and vegetable in your diet and avoiding salty, high fat, junk food. Your metabolic rate goes up with your temperature.


  • NIOSH Fast Facts “Protecting Yourself from Heat Stress”
  • CDC-Extreme Heat and Our Health. cddc.gov
  • Guyton, AC: Human Physiology and Mechanisms of Disease, Philadelphia, WB Saunders, 2007
EMS reponding to heat stroke
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