Heat stress or heat-related illness is one of the leading hazards of working in high-heat environments such as foundries and steel mills. Identifying and recognizing the hazard leads to identifying protective and preventive solutions that will keep you and your team safe and healthy.

How does heat stress work?

For the average working-age adult, the human body works to maintain a constant internal body core temperature of 97-99 degrees F (36.1-37.2 degrees Celsius). When a person is exposed to high-heat conditions, oftentimes with high levels of humidity, the body struggles to stay within its normal range and sweats to regulate the temperature.

In high-heat, high-humidity conditions, the ambient air is already saturated with water droplets, causing less evaporation or cooling of the surface of the skin. This is why on hot, humid days your body can feel “sticky” as the sweat on the skin can’t evaporate and remains on the body.

When the body sweats, it loses water out of the cells along with electrolytes (potassium, magnesium, sodium, others), causing both dehydration (loss of water) and a chemical imbalance that supports muscle functions and controls breathing and pulse rate. These changes, when not properly addressed, develop into heat stress that ultimately can lead to fatal results.

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Types and Treatment of Heat Stress

It’s important to know how to recognize the signs and symptoms of heat stress and how to properly treat it when it occurs. This will help you conduct an effective risk assessment of high-heat work areas and tasks and lead to preventive actions that will keep your team safe and healthy.

Heat Cramps

Heat cramps are painful muscle spasms that occur when an over-exerted muscle loses important nutrients (electrolytes) through sweating and overheating. The cramps generally occur in the muscles that are being overworked, such as the arms, legs, shoulders, and abdomen. The more you sweat, the more water and electrolytes you lose, and the more cramps you experience.

Muscle cramping in high-heat environments is your clue that your body is overheating and dehydrating. Recognize this condition early and take corrective actions, such as taking a break in a cooler environment, drinking more water, and drinking sports drinks that replace electrolytes. Gently massaging the affected muscle can help with circulation and applying a cold compress can help remove the excess heat.

It’s generally acceptable to remain at work, but the rest of the shift should be performing duties that don’t continue physically stressing the cramping muscles.

Heat Exhaustion

With heat exhaustion, the body overheats and loses its ability to cool itself, meaning it now needs help to remain at normal body temperature. It’s possible to experience heat exhaustion without feeling heat cramps first.

A person experiencing heat exhaustion will have a “mild” temperature, meaning the internal core temperature is over 99 F (37.2 C), up to 102 F (38.9 C). As with any mild fever, signs and symptoms include profuse sweating and soaked clothing, dizziness, fatigue, and the early stages of shock (pale, cool, clammy skin). The person experiencing heat exhaustion may not recognize what’s happening, but alert co-workers can and must immediately assist the person.

Once recognized, treatment must include removing the person from the heat, providing tepid or cool (not ice) water and/or a sports drink to rehydrate and replace the lost electrolytes. The person may continue working after a short break of 30 to 60 minutes, but only in a cooler environment with reduced physical exertion, such as in an office area. Continue drinking water and rest.

If the person returns to work the next day, observe the person and ensure the person has access to plenty of water to stay hydrated.

Heat exhaustion is the precursor to heat stroke, which can lead to death. So pay attention!

Image of worker experiencing heat stress

Heat Stroke

Heat stroke is a true medical emergency! A person experiencing heat stroke has passed through the heat exhaustion phase to being fully dehydrated, with an internal core temperature that exceeds 104 F (40 C). The sweat glands are empty and can no longer function. The high-grade fever affects the brain cells, and the loss of electrolytes and water can impact the heart muscle and breathing.

A person suffering heat stroke will go from wet clothing and profuse sweating (heat exhaustion) to hot, red, dry skin and clothing that is being dried literally from the inside-out. Without immediate cooling, that person will die!

Treatment includes calling 9-1-1, removing the person from the high-heat environment (perhaps carried to a cooler location), and placement of ice packs around the body (behind the neck, in the arm pits and groin areas, behind the knees). If available, use a low-pressure water hose or emergency shower to wet and cool the person. If unconscious, don’t give anything to drink but continue the cooling process until the medics arrive.

This person must be taken to the hospital immediately, where treatment will include an ice bath, cold-fluid IVs, and likely observation overnight to bring electrolyte levels back to normal. The patient will likely be out of work for at least a couple of days, if not longer.

Note: if a heat stroke event occurs at work, it will be an OSHA-reportable incident, as in-patient hospital care will likely be required.

Preventing Heat Stress

Heat stress is preventable! Knowing the conditions that can cause heat stress allows you to ensure protective/prevention measures are in place.

Acclimatizing to heat

The human body can adapt to high-heat environments over time, generally requiring at least five days. Working in a foundry or other high-heat locations means heat stress conditions exist year-round, regardless of outdoor temperatures. New hires need time to acclimatize to the work, requiring frequent breaks initially and access to plenty of water.

Experienced workers who take extended vacations or time away from work may need adjustment time upon their return. In addition to this bodily adjustment to the temperatures, additional measures are necessary to ensure a person’s safety and health in these conditions.

Image of worker drinking water


You have likely heard that drinking 64 ounces of water a day is average for ‘normal’ work environments and that more is needed when in high-heat environments. Considering a person’s body is composed of 60% water and can sweat out up to three (3) gallons of fluid a day, staying hydrated is a critical component to preventing heat stress.

Water should be your primary drink, but don’t overlook the electrolyte-replacement (sports) drinks. The more you sweat, the greater the need to replace those electrolytes. It’s generally accepted to drink one sports drink to every 3 drinks of water, if each drink is of equal amounts.

A quick way of identifying whether you’re adequately hydrated is by looking at the color of your urine. A pale-yellow color suggests you’re properly hydrated. As it gets darker in color, it means you need more fluid intake.

On that note, the recommendations include water, sports drinks, milk, tea, coffee, and juices. It does not include alcohol. Alcohol is a dehydrator, removing water from cells as well as increasing sugar intake, which makes a person thirstier. Also, don’t rely on thirst as your mechanism to drink more fluid. When feeling thirsty, you are already 20+% dehydrated. So, drink water even if you don’t feel thirsty.

Keeping Cool

While staying hydrated, you also need to help your body temperature remain in the normal range, meaning you must help it remain cool. Things to consider include:

  • Lightweight, light-color clothing (you still need to wear PPE to protect from other hazards)
  • Lighter, cooler foods (fruit, salads, cold sandwiches – no microwave dishes)
  • Frequent breaks in cooler environments
  • Air movement for ventilation and airflow (if ambient air is under 100 F (37.8 C)
  • Identifying lighter, cooler, breathable PPE without compromising safety)

PPE options

Today, PPE manufacturers are working with industries to identify more comfortable, better-fitting, more functional PPE that offers the needed protection while helping reduce secondary hazards created by the PPE (such as over-heating).

Chicago Protective Apparel, a division of Mechanix Wear, offers clothing and accessories for high-heat work environments that use the latest technology and manufacturing practices to provide light-weight PPE without compromising the wearer’s safety and health.

For high-heat work environments, whether you need aluminized levels of protection, fire-retardant greens, or protection from welding, Chicago Protective Apparel and Mechanix Wear are ready to help you discover the best PPE for your specific needs.

Mechanix Wear’s TRACK Program involves partnering with PPE experts who will work with you to conduct a risk assessment at no cost to you. This is a full package, including recommendations for PPE that match your specific findings and needs and providing the PPE to trial, using your front-line employees, prior to any commitment to purchase.

Your employees participate in the PPE selection process while testing it to know exactly how it will work and how it will fit. This step alone saves you time and money, knowing that purchasing the right PPE for the identified hazards will lead to better compliance, protection, and safety of your employees.

In addition, Mechanix Wear offers PPE made of materials that provide cooling, breathability, and durability for comfort, protection, and long-lasting wear.

Heat stress is a real hazard in high-heat, high-humidity environments. Not recognizing the onset of heat stress can result in fatal consequences. Partnering with PPE experts, such as Chicago Protective Apparel and Mechanix Wear, can provide effective risk assessments paired with the appropriate PPE that will save your employees and save you in costs by purchasing the right PPE the first time.