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Careless Accident or the First Sign of Heat Stress?

It's the dog days of summer, and you are supervising a crew at a jobsite. Yes, it’s hot enough to fry an egg on the sidewalk, but your guys are experienced; this is not their first rodeo when it comes to working out in the heat.

William Tomlin1

William Tomlin

You have trained them on the basics of working hard on hot days. Then out of the blue one of your better workers does something completely out of character and gets injured on the job. An investigation reveals the accident was not only preventable, but that the employee's actions was the culprit, going against all of his past training, even his previous safety-consciousness while working in similar situations. While you might be thinking, “what gives?" increased accident frequency is a prime indicator of heat stress.

Employees working in hot environments react to heat strain through displays of irritability, anger and other emotions. An angry, irritated person is likely to act rashly and take unnecessary risks. Studies done by the Mine Safety and Health Administration (MSHA) on employees in hot work environments found that heat strain has a negative effect on dexterity, coordination and alertness while performing lengthy and monotonous tasks. Furthermore, heat strain can affect one's ability to make quick decisions when a decision to ensure a safe outcome is necessary. Other studies conducted on workers in coal mines found that the lowest accident rates occur when men are working at temperatures below 70º F; the highest accident rates occur at temperatures of 80º F and over.

To avoid heat stress, it's important to review the basics. The Occupational Safety and Health Administration (OSHA) indicates heat stress is a progressive disorder that begins with mild symptoms that, if not mitigated early-on, can lead to death.

The first stage is HEAT FATIGUE. Signs and symptoms of heat fatigue include the inability to complete complicated physical tasks or focus on the job at hand. The worker may appear to be “out of it,” even slightly confused. There is no treatment for heat fatigue except to remove the worker from the heat stress before a more serious heat-related condition develops.

The next stage is HEAT CRAMPS, which are usually caused by performing hard physical labor in a hot environment. Thirst cannot be a reliable indicator for the need for water; instead, water must be replenished every 15 to 20 minutes in hot environments.

If the above actions are not taken, symptoms can proceed to HEAT EXHAUSTION/HEAT COLLAPSE. Signs and symptoms include headache, nausea, vertigo, weakness, thirst and giddiness. This condition responds readily to a prompt response of fluids and cooling. Heat exhaustion should not be dismissed lightly. Oftentimes fainting associated with heat exhaustion can be an underlying cause of an accident. For example, heat exhaustion victims could be operating machinery or controlling an operation that should not be left unattended; moreover, a victim may be injured while he or she faints. The basic treatment from heat exhaustion is to remove the employee from the hot environment and give them cool, non-carbonated water or fluids.

The final stage is HEAT STROKE, which occurs when the body's system of temperature regulation fails and body temperature rises to critical levels. Heat stroke is a medical emergency. The primary signs and symptoms include extreme confusion, irrational behavior and loss of consciousness. Symptoms may also be combined with convulsions; a lack of sweating; hot, dry skin; and an abnormally high body temperature. If body temperature is too high, it can cause death. Regardless of the worker’s protest, no employee suspected of being ill from heat stroke should be sent home or left unattended. Instead, professional medical treatment should be obtained immediately and:

  • The worker should be placed in a shady area and their outer clothing should be removed.
  • The worker's skin should be wetted and air movement around the worker should be increased to improve evaporative cooling until professional methods of cooling are initiated and the seriousness of the condition can be assessed.
  • Fluids should be replaced as soon as possible.

Here are some simple and effective tips from the Centers for Disease Controls and Prevention (CDC) to prevent heat stress related accidents:

  • Train workers to recognize and treat the signs of heat stress. Be sure all workers know who has been trained to provide first aid. Also train supervisors to detect early signs of heat-related illness and permit workers to interrupt their work if they become extremely uncomfortable.
  • Work in pairs, use the buddy system. Teach employees to keep an eye on each other.
  • Help workers adjust to the heat by assigning a lighter workload and longer rest periods for the first 5 to 7 days of intense heat. This process should be repeated when a worker returns from vacation or an absence from the job.
  • Encourage workers to drink plenty of water. About 1 cup of cool water every 15 to 20 minutes, even if they are not thirsty.
  • Encourage workers to avoid alcohol, coffee, tea and caffeinated soft drinks that dehydrate the body.
  • Encourage workers to wear lightweight, light-colored, loose-fitting clothing. Workers should change their clothes if they get completely saturated.
  • Use general ventilation and spot cooling at points of high heat production. Good airflow increases evaporation and cooling of the skin.
  • Schedule heavy work for cooler times of the day and use appropriate protective clothing. Alternate work and rest periods, with rest periods in a cooler area. Shorter, more frequent work-rest cycles are best.

The bottom line? Even moderately hot work environments can be a root cause of accidents. This summer, be sure all employees and supervisors are trained to identify and mitigate the symptoms of heat stress. For more information, visit our website at www.usfsafetyflorida.com, where we feature a YouTube video on heat stress and you can download OSHA's heat stress poster in English and in Spanish. You can also request an on-site consultation, and we will come to your worksite and provide advice on how to mitigate heat stress conditions.

Resources from NIOSH, OSHA, the CDC and EPA:

Working Outdoors in Warm Climates (from OSHA)

Working in Hot Environments (from NIOSH)

"Extreme Heat" (from the CDC)

"NIOSH Safety and Health Topic: Heat Stress"

Protecting Workers in Hot Environments (from OSHA)

The Heat Stress Quick Card (from OSHA)

Heat Stress in Agriculture (from the EPA)


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