Prioritizing Heat-Illness Prevention
U.S. Army Public Health Center
Aberdeen Proving Ground, Maryland
The Occupational Safety and Health Administration (OSHA) is targeting occupational heat injury and illness prevention as part of its recent efforts to establish a universal standard to protect workers. According to OSHA, “Heat is the leading cause of death among all weather-related phenomena, and it is becoming more dangerous, as 18 of the last 19 years were the hottest on record.”
OSHA tracks workers who develop medical conditions or die from excessive heat exposures, and identifies those in construction and agriculture to be at the highest risk. These medical conditions, referred to as heat illnesses or injuries, occur when the body is unable to compensate for increased body temperatures due to hot and humid environmental conditions and exertion.
Military personnel are also at risk, especially during outdoor training exercises that involve rigorous physical exertion. Physically intense military activities such as Basic Combat Training, field training exercises and road marches over 8 kilometers are examples of high-risk activities. Physical training tests and running competitions are also risky events. Additionally, Soldiers usually must wear full uniforms, sometimes with added protective layers, and may carry heavy gear, which can further increase internal body temperatures.
Severe cases can be life-threatening, but even mild heat illnesses can mean a person is at greater risk during future heat exposures.
“The most severe condition is heatstroke, which can be fatal if not treated immediately and properly,” said Maj. Aeri Hodges, chief of Public Health Nursing at Bayne-Jones Army Community Hospital, Fort Polk, Louisiana. Hodges added that though heat exhaustion is a less severe diagnosis, it could progress to heatstroke if the exposure is not stopped and the condition not treated.
The risk to Soldiers is highest when outdoor temperatures and humidity are high, which is the case at some of the Army installations where outdoor training occurs. Of the 43 Army installations tracked for the 2020 Health of the Force (HOF) report, 10 experienced more than 100 heat risk days in 2019, mostly concentrated in the south and southeast United States. Nearly 40 percent of active-duty Soldiers were stationed at one of these locations.
According to OSHA, climate change is increasing the frequency and intensity of extreme heat events, as well as increasing daily average daytime and nighttime temperatures. The potential for this to increase the risk of heat-related conditions has also been recognized by the U.S. Army Public Health Center. In addition, the 2020 HOF (pages 74-75) indicates that increased temperatures may increase the risk of suicides, assaults and vehicle accidents.
Because of the uniqueness of military activities, the APHC tracks its cases and prioritizes the prevention of heat-related injuries and illnesses through policies, routine surveillance, specific work teams and mandated annual training. Lt. Col. Michael Superior, a preventive medicine doctor and chief of the Disease Epidemiology Branch of the APHC, said that heatstroke and heat exhaustion are reportable medical events that must be reported by military health care providers through the Disease Reporting System internet (DRSi).
“We collect data on these events throughout the entire calendar year and publish monthly reports during the traditional heat season, April through September,” Superior said. “We also report surveillance information and assess heat illness trends in the annual HOF report.”
Though cases reported through the DRSi are highest during the warmer months of May through September, Soldier heat-related casualties occur throughout the year.
“Fluctuating and warmer-than-expected temperatures in winter can still be a problem,” Hodges said. She noted that heat exhaustion cases have occurred in winter months in just 70 F weather.
There are an average of two to three heat-related Soldier deaths each year. The number of heatstroke and heat exhaustion cases among Soldiers decreased in 2019 compared to 2018 but was still higher than cases in the prior three years.
“While it may be impossible to avoid excessive heat exposure, there are several prevention strategies that we know can help reduce the chances of becoming a heat casualty,” Hodges said. She encourages Soldiers to use the buddy system and monitor each other’s hydration and physical condition. Hodges added that seeking medical help at the earliest signs or symptoms of a heat-related condition could save a life.
As the weather warms and outdoor training increases, Soldiers should remember their heat illness training and these tips from the APHC Heat Illness Fact Sheet to help protect themselves and others:
- Use the Army Wet Bulb Globe Temperature (WBGT) index to determine WBGT risk categories and plan ways to reduce the risk, including:
- Consider ways to lighten loads and modify clothing to increase air circulation.
- Consider conducting high-intensity activities when temperatures are cooler, such as at night, before sunup or in the shade.
- Add 5 degrees Fahrenheit to the WBGT for rucksack or body armor and 10 degrees for full chemical protective gear to capture the actual risk level.
- Consider the prior days’ WBGT exposures since multiple days’ exposures often add risk.
- Gradually increase exposure (e.g., two weeks or more) to warm climates and higher exertion in warm climates; increase rest periods during high exertion.
- Follow Army Work/Rest and Water Consumption guidance, remembering not to exceed 1 quart/hour, or 1.5 quarts/hour when doing intense physical activity, since excessive water consumption could lead to a serious chemical imbalance called hyponatremia.
- Assess first-morning urine with urine color charts to assess adequate day-to-day fluid intake.
- Take personal risk factors into account. Factors that increase the risk of heat injury include previously having an heat illness, not being adequately fit, currently being ill, ignoring early signs or symptoms, and/or having recently used alcohol or certain drugs (e.g., antihistamines, blood pressure medications, decongestants, antidepressants and some diuretics).
For more information on preventing heat illnesses, check out the following resources from the APHC and OSHA:
Risk factors for heat illnesses include:
- Environment: high temperature, high humidity, wind, solar load, repeated hot/humid days
- Mission: high exertion/intensity, heavy loads/gear, repeated strenuous days
- Individual: acclimatization status; poor fitness (2-mile run greater than 16 minutes for males, greater than 19 minutes for females); body mass index (BMI) greater than 26; age less than 20 or greater than 40; poor hydration/nutrition status; minor illness (fever, skin rash, sunburn or poison ivy); medication (antihistamines, decongestants, some blood pressure medications, some psychiatric drugs); alcohol use in the past 24 hours; sleep deprived; highly motivated