Extreme Heat Survival Guide: The Outdoor Worker
Extreme heat kills more Americans than any other kind of weather-related deaths, according to the National Weather Service. A 2023 CAP report estimated that each summer, “heat event days would be responsible for almost 235,000 emergency department visits and more than 56,000 hospital admissions for heat-related or heat-adjacent illness, adding approximately $1 billion in health care costs". A significant proportion of the North American population is engaged in working outdoors. Heat related incidents are often underreported due to misclassification or lack of awareness, as heat stress can trigger conditions like asthma, heart attack and stroke.
From a 2023 publication National Library of Medicine, "Occupational heat stress, heat-related effects and the related social and economic loss: a scoping literature review" - In the United States, about 32 million people work in outdoor-focused occupations. The U.S. Bureau of Labor Statistics indicated that 4.3% of civilian workers were required to spend more than two-thirds of their workday outdoors. This percentage varied significantly across occupations; for instance, 89.9% of landscaping and grounds keeping workers and 79.0% of construction laborers spent more than two-thirds of their working time outside. CAREX Canada estimates approximately 1.5 million workers, about 9% of the workforce are exposed to solar ultraviolet radiation (UVR) due to their outdoor occupations.
Although construction and agriculture workers usually come to mind, many community and support services require either full day or significant exposure working in the heat. Not comprehensive but to list examples of occupations that require work, even in extreme heat: roofing, brick laying, road and utility work, farming, landscapers, delivery, traffic guards, parking attendants, policing, military, lifeguarding, event workers, outdoor vendors, restaurant, smelting plants, and manufacturing plants with open furnaces or heat generating equipment. Indoor environments can pose significant heat stress risks, especially in poorly ventilated areas or spaces with heat-generating equipment, like restaurants, factories and indoor facilities without air conditioning. Both indoor and outdoor workers should be aware of heat stress hazards.
It is important to note that heat stress and heat-induced illnesses are the result of elevated core body temperatures above 104°F (40°C) and fatality often occurs within 30 minutes. Temperatures for the worker are influenced by many external factors such as: air temperature, relative humidity index, direct sunlight or solar radiation or UV, radiant heat emitted from surrounding surfaces, such as buildings, ground materials and wind speed. Ambient temperatures and radiant temperatures can differ significantly and distort the true effects of extreme heat. To compound the distortion, core body temperatures are influenced by the clothing and the health of the individual to adapt to heat. The following are examples of common occupations that bring to light the deceptive nature of extreme heat and reasons to be vigilant and take the necessary precautions.
Actual heat-related case studies are taken from Occupational Health and Safety Administration website.
Case Study 1: Roofer
In July, a 42-year-old man started a new job as a roofer. His employer did not have a formal plan to protect new workers from heat-related illness although there was plentiful water, ice, and Gatorade available at the site. The worker felt fine during his first two days of work. His third day on the job was slightly warmer, with a high temperature of about 86°F and relative humidity of 57%, for a heat index of 90°F. In the afternoon, the worker told his co-workers he felt hot and sick. He climbed down from the roof and went to sit by himself in the sun. When his co-workers checked on him a few minutes later, he had symptoms of heat stroke. He was taken to a hospital where he died.
Taking a closer look at the 42-year-old roofer, it is unclear what actions were taken but the most important measurement is the roofer's core body temperature. Although the relative heat index of the local general area was 90°F taken at the airport, what is not clear is the temperature on the actual roof. A typical unpainted metal roof can reach temperatures between 138°F and 145°F in the summer sun. A typical asphalt metal roof, particularly a dark colored one, can reach temperatures around 150°F to 168°F on a hot summer day, with the potential to get even hotter depending on the color and direct sunlight exposure; significantly hotter than the ambient air temperature. It is fair to assume the roofer was wearing roofer's clothing and gear that stores the heat but also hinders perspiration. Finally sitting in the sun unattended, the ultraviolet rays or radiant heat further increased the core body temperature. There is no information on the 42 year old's health, how long he was working, the workload, whether he had pre-existing conditions, whether he exhibited any signs or symptoms of heat stress or any treatment was provided to reduce core body temperatures within the critical period.
Case #2: Delivery worker
A 50-year-old man had been working at a delivery company for six years. His job involved driving a vehicle and walking in residential neighborhoods to deliver mail and packages. In late May, the weather suddenly became hotter. On the second day of hot weather, the worker developed cramps and heat exhaustion. He was hospitalized for two days with acute kidney failure due to dehydration. His condition improved after intravenous fluid replacement. It is common for even the most experienced workers, challenged with meeting quotas, conscientious about service and work deadlines to delay, ignore or fail to schedule regular rehydration, cooling breaks, carry cooling equipment and take the necessary steps to prevent heat-related illnesses.
Case #3: Foundry worker
A 35-year old employee had worked at a foundry for six years. The indoor workplace had high levels of environmental heat from ovens and molten metal. His normal job tasks were in a cooler area of the building. On the day of the incident, he was asked to perform a job in a hotter environment near an oven. He wore heavy protective clothing to prevent skin burns. After several hours of work, the man collapsed and died of heat stroke.
Important Lessons:
1) Heat Stress is a silent, progressive illness that within minutes quickly develops 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) Advertised local temperature readings are only indications and temperatures at the actual worksite may differ dramatically. Temperatures at 80°F and up are high enough to result in a Heat Index value of 90°F and cause heat stroke 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, heavy work loads, heavy clothing, protective wear, the ability to cool and preventative cooling techniques. For example, road construction asphalt mix typically arrives at the job site at a temperature between 275°F and 300°F degrees, significantly increasing the temperature of the surroundings.
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. The estimated time for heat stress to lead to death is 30 minutes from the onset. Sara Kendall of BC Emergency Health Services shares that, “heat stroke has a remarkably high mortality rate, up to 62.6% of heat stroke patients who arrive at 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.
4) When experiencing heat-related symptoms, seek immediate medical assistance and do not be alone. Find a buddy or call a friend. Move to a shaded cool location. The fastest way to cool down is full body cooling performed by medical professionals with constant monitoring and if that is not available, cool down by targeting the core body zones with cold therapy.
5) Schedule and practice Pre-Cooling and regular Periodic Cooling Breaks before going into the heat. Check out our Krazy Kool TechnologyTM Systems and the science behind our Cold Therapy - "Science of Kool".
