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  • Writer's pictureAIM Team

DOLIR: Prepare to avoid worker heat injuries

Every year thousands of workers become ill while working in extremely hot and humid conditions and some of them die as a result. These conditions can be encountered outside on hot summer days but also can be present in some indoor locations as well. Employers have a duty to protect workers from this known hazard and many have learned methods that have prevented heat related injury and illness. These same methods can be used in the home to prevent heat illness or death due to summertime yard work, DIY projects, and outdoor recreation. OSHA has conducted heat illness prevention campaigns in an effort to help this preventable cause of occupational injury and death. Regarding heat injury and death OSHA has a simple safety message – Water. Rest. Shade.

Hazardous heat exposure can occur both indoors and outdoors if the conditions are right. Outdoor exposures include agriculture, construction (esp. roofing and road work), landscaping, mail and package delivery, and oil and gas well operations. Indoors can include bakeries, kitchens, laundries, electrical utilities, fire service, iron and steel mills, manufacturing, and warehousing.

Anyone can be affected by a range of heat related illnesses regardless of age or physical condition. Employers with workers that are exposed to high environmental temperature or hot indoor areas should develop a complete heat illness prevention program.

Provide workers with water, rest, and shade - Take frequent breaks in a cooler location with cool liquids to rehydrate and cool the body on the inside and outside. Pause physical activity to allow the body to cool down.

Acclimate to the hotter conditions - Allow new or returning workers to gradually increase workloads and take frequent breaks as they acclimatize and build a tolerance for working in the heat. 50% – 70% of heat related fatalities occur in the first few days of exposure because the body has not built a tolerance to the heat gradually over time. The body’s process of building tolerance is called heat acclimatization, and not allowing for this heat tolerance development can be a major risk for illness or death.

Plan for emergencies and train workers on prevention – Someone needs to provide daily oversight and consider how heat stress will be measured. Monitor the temperature and humidity by considering the heat index and be alert to heat advisories when they are issued.

Monitor workers for signs of illness - Train workers on how to recognize and treat heat related situations and what first aid to administer. Heat conditions can change rapidly. Workers’ bodies have responses to cope with heat stress. Heart rate increases and sweating becomes more profuse. Skin temperature and eventually core body temperature will rise. These are signs of heat stress. If the skin turns red and hot but dry, this can be leading to heat stroke. Heat related illness in order of severity include:

  • Rhabdomyolysis – Muscle pain and weakness.

  • Heat rash – clusters of red bumps on the skin.

  • Heat syncope – Fainting, dizziness.

  • Heat cramps – Muscle spasms or pain usually in the arms, legs, or trunk.

  • Heat exhaustion – Fatigue, irritability, thirst, nausea or vomiting, dizziness, heavy sweating, elevated heart rate and body temperature.

  • Heat stroke – Confusion, slurred speech, unconsciousness, seizures, heavy sweating or hot/dry skin, very high body temperature, rapid heart rate.

When in doubt, cool the worker and call 911

Be aware of personal risk factors that can cause some workers to handle heat stress less effectively including obesity, diabetes, high blood pressure, heart disease, lower level of physical fitness, effect of some medications, alcohol use, or illicit drug use. This list is not all inclusive but be aware that not every worker can tolerate heat the same way. For more information go to

Additionally, you can add an app called the “NIOSH Heat Index Safety Tool” on your Android or Apple mobile device for the NIOSH heat index. It will give you the calculation at your location or you can load the temperature and humidity to determine the relative heat index.

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