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6 Serious Consequences of Heat Stress

By Joyce Wooley
Published: May 29, 2018 | Last updated: November 9, 2018 02:55:59
Presented by Radians
Key Takeaways

Educate your workers about heat stress and establish a heat stress safety plan to make sure none of your employees have to experience these six effects of heat stress.

Source: Robert Bayer /

The heat workers throughout much of the country experience from June to September presents a serious health and safety hazard. On days when the temperature climbs near 100°F with high humidity, outdoor workplaces and job sites can be uncomfortable and, if you’re not prepared, downright dangerous.


Luckily, you're not helpless in the face of these risks. While you can't do anything about the temperature, understanding the serious consequences of heat stress can help you prevent heat-related injuries and illnesses.

What Is Heat Stress?

Heat stress occurs when your core body temperature increases significantly but your body isn't able to cool itself by sweating.

Who is at risk? Sensitivity to heat varies among the population and is influenced by age, weight, physical fitness, use of alcohol or medications, hydration level, and various medical conditions. But anyone who works in the heat for prolonged periods can succumb to heat stress.

Workers in operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities are generally at the highest risk.

Six Serious Consequences of Heat Stress

Heat stress is no joke, and its effects can range from slight discomfort to life-threatening illness. Here are six of its most common consequences.

1. Mental Fatigue

Studies have shown that even a two percent dehydration level due to heat stress dramatically decreases a worker’s mental performance and ability to focus.

In fact, a performance study by NASA concluded that at temperatures of 80°F, workers make five errors per hour and 19 per three hours. At 95°F, the number of mistakes increased to 60 per hour and 138 every three hours – without the worker realizing it.

This study observed telegraph key operators at work, so their mistakes were not critical, but you can just imagine what would happen if a heavy machine manufacturer made an average of one mistake every minute.

2. Impaired Decision-Making and Decreased Reaction Time

Several studies have looked at the link between heat stress dehydration, the decision-making process, and work-related accidents. One particular study found that two percent of body weight loss due to dehydration impaired visual motor tracking, short-term memory, attention, and arithmetic efficiency. At an extreme four percent of body fluid loss, the study noted a 23 percent reduction in reaction time as compared to a properly hydrated individual.


It goes without saying that dehydration can be a severe workplace hazard in occupations where attention to detail or fast reaction time is key to maintaining operational safety.

3. Physical Exhaustion

At high temperatures, the body must work extra hard to cool itself. Studies have demonstrated that when ambient temperatures reach 95°F, the body moves half of its blood to the skin to produce moisture. Unfortunately this means that the remaining organs have to operate with only half the blood they normally require, leading to a lack of oxygen for working muscles.

After a prolonged period of working in the heat, the heart simply cannot meet the peak oxygen needs of each of the organ systems while adequately cooling the body. This is the point where workers feel extremely dehydrated and experience of physical exhaustion and muscle fatigue.

Productivity lags as a result of this exhaustion. In a study that placed forest workers in a controlled environment where one group was properly hydrated and the other dehydrated to just one percent of body weight loss, researchers found a 12 percent decrease in productivity from the dehydrated group.

4. Heat Rash

Heat-related rashes are the most common problem observed in hot work environments. Caused largely by sweating, heat rash looks like a cluster of red pimples or small blisters and may appear on the neck, upper chest, groin, under the breasts, or in the elbow creases.

The best antidote to heat rash is a cooler work environment with less humidity. The rash should be kept dry; ointments or anything that moistens the skin may make it worse.

While heat rashes themselves are not inherently dangerous, there can be complications if they aren't treated by moving the worker to a cooler environment. An untreated heat rash can become infected or reduce sweating, compromising the body's ability to regulate its temperature. Since these areas of skin are damaged, they may also be more susceptible to absorbing toxic chemicals.

Free Download: Hot Weather Survival Guide

5. Heat Exhaustion

Heat exhaustion is often a precursor to the more serious heat stroke and is generally accompanied by a slightly elevated core body temperature.

Symptoms of heat exhaustion include:

  • Headache
  • Nausea
  • Dizziness
  • Weakness
  • Irritability
  • Confusion
  • Thirst
  • Heavy sweating
  • Decreased urine output.

Workers with heat exhaustion should be removed from the heat, given liquids, and cooled with cold compresses while awaiting medical evaluation.

6. Heat Stroke

Perhaps the most serious consequence of heat stress, heat stroke is considered a serious medical emergency and occurs when the body’s heat regulating system fails. It includes a major disruption of the nervous system and a body temperature in excess of 104°F. Workers suffering from heat stroke may or may not continue sweating.

It’s imperative that those showing signs of heat stroke be taken to a shady area and cooled rapidly using ice while waiting for medical care.

Ensure Worker Safety with a Comprehensive Heat Stress Program

Educating your employees is one of the most important steps you can take to prevent workplace accidents related to heat stress. Reduced cognitive function, attention span, and visual motor tracking can have deadly consequences in many workplaces – but it’s completely preventable.

Establishing a workplace safety program for heat stress is critical for any organization that places workers in hot environments. Teach employees to recognize the hazards and to know what steps to take to prevent heat-related illness. Ensure supervisors make accommodations for the heat, where possible, including adjusting working schedules and providing a shady area with plenty of access to drinking water. Cooling towels, headbands, head shades, and neck wraps can also offer workers relief from the heat because they help to accelerate the evaporative cooling.


By educating employees, you can reduce heat stress. And by reducing heat stress, you can create a safer workplace with fewer accidents and increased productivity. Everyone benefits from taking a more careful approach to working in the summer heat.


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Written by Joyce Wooley | High Visibility / Outerwear Development Manager

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Joyce Wooley has more than two decades of experience in the apparel industry. She is recognized as an executive with vast experience in raw materials, product development, global sourcing, production management, factory standards, social compliance and supply chain management.

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