Hot, Humid And Healthy

During the summer, hot weather increases the risk for heat-related injuries and illnesses. Since 2008, more than 100 workers have been killed on the job as a result of heat stress. Therefore, it is crucial to understand the risks and symptoms associated with heat-related injuries and illnesses and to know how to prevent them on the job.

Heat stroke is the most dangerous of all heat-related illnesses. It occurs when the body loses the ability to regulate its own temperature. The average human body temperature is 98.6°F, and shifts of even a few degrees can cause serious harm. 

Working in hot or humid conditions increases the risks for heat stroke. Symptoms include dry/hot skin, a loss of sweating ability, mental confusion, convulsions, delirium, and a loss of consciousness; a heat stroke victim may even fall into a coma. When someone exhibits these symptoms, it is imperative to get immediate medical attention. While waiting for medical personnel, move the victim to a cool place, soak the victim’s clothing with cool water, offer the victim small sips of water and vigorously fan him or her.

Another illness, heat exhaustion, is caused by dehydration from working in high temperatures and/or humid conditions. Symptoms of heat exhaustion include clammy, moist skin and pale complexion. Extreme fatigue, headache, nausea, vomiting, dizziness or even fainting often accompany these indicators. Heat exhaustion can be treated with similar tactics as heat stroke.

Sunburn is another common heat-related ailment in the workplace. According to the Centers for Disease Control and Prevention (CDC) Workplace Safety Guide, “Sunburn is an often painful sign of skin damage from spending too much time outdoors without wearing a protective sunscreen. Years of overexposure to the sun lead to premature wrinkling, aging of the skin, age spots, and an increased risk of skin cancer.”

Unlike a thermal burn, sunburn is not immediately apparent. Symptoms usually start about four hours after exposure, worsen in 24–36 hours, and resolve in three to five days. Symptoms may include red, warm and tender skin; swelling; blistering; headache; fever; nausea; and fatigue. The pain from sunburn is the worst six to 48 hours after exposure. Skin peeling usually begins three to eight days after exposure. Sunburn also increases the risk of dehydration. 

Sunburn can be prevented by wearing sunscreen on exposed skin; you can also wear a hat that allows air circulation around the head. Sunglasses or safety glasses with ultraviolet (UV) protection may also be worn.

Less severe conditions that may occur when working in extreme temperatures include heat cramps and heat rash. Heat cramps are muscle spasms associated with dehydration that usually occur in the calf muscles. If heat cramps become common, consult a doctor. Heat rash occurs when sweat causes wet or moist clothing to rub against the skin. It can be prevented by resting in a cool place and allowing sweat to dry.

Working in hot and humid conditions can also result in fainting, which occurs most frequently from standing still for extended periods of time. Victims often recover from fainting after a period of rest. Workers who are 65 years of age or older, are overweight, have heart disease or high blood pressure, or take medications that may be affected by extreme heat are at the highest risk for fainting and heat-related injuries and illnesses.

A few ways to avoid and prevent heat- related injuries and illnesses include drinking plenty of fluids throughout the day; taking periodic breaks in cooler areas; and avoiding caffeine, alcohol and very cold drinks. Cold drinks can cause stomach cramps.

It is also imperative to be aware that hot and humid conditions can increase the risks of injuries caused by other occupational hazards. For example, such conditions can result in sweaty palms, fogged-up safety glasses and dizziness; the last item increases the risk of other types of occupational injuries, such as slips, trips and falls.

Heat-related injuries and illnesses can have immediate and long-term effects on workers and can result in lost productivity for employers. Therefore, preventing heat stress in the workplace is vital. Employers should train workers so they understand what heat stress is, how it affects their health and safety, and how it can be prevented. 

If you would like more information, the Occupational Health and Safety Administration website at contains a number of training and informational resources about heat-related injuries and illnesses.

About the Author

Tom O'Connor

Safety Columnist

Tom O'Connor is safety and regulatory affairs manager for Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Reach him at


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