Construction worker wiping sweat.

Employers and Employees Can Work Together to Prevent Heat-related Illness

By Michelle Hopkins | 07/09/2020

Heat-related illness occurs when the body loses its ability to cool due to prolonged or intense exposure to hot temperatures. This sends blood rushing to the skin surface and away from the brain and other organs, leading to their damage, if not addressed. If steps are not taken, an employee may experience the most serious consequences of heat-related illness: heatstroke, permanent disability, or death.1 But there is positive news. Employers and employees can work together to prevent heat-related illness by monitoring the heat index, watching for the signs of heat-related illness, and taking preventive action.

Validating the need to monitor

If heat-related illness is preventable, why did it bring suffering to 70,000 employees and death to more than 800 between 1992 and 2017?2 It’s puzzling but possible theories might include:

  1. Lack of awareness and understanding
  2. Difficulty focusing time and energy on preventive measures
  3. An attitude of “I’ll just tough it out,” while trying to ignore the heat

In the 20 years since she joined Concentra®, Ronda McCarthy, MD, MPH, FACOEM, has raised awareness of heat-related illness on the national stage through conferences, webinars, and Congressional testimony.3,4 She leads a panel of Concentra medical experts in providing guidance to clinicians and employers on standards and laws related to hazardous workplace exposures, including heat. Building awareness and understanding about heat-related illness is essential to a healthy workforce, she says. With increased knowledge, myths about heat stress (prevention is unnecessary, too time-consuming, or excessively expensive) can melt away.

“Today, there is no national Occupational Health and Safety Administration (OSHA) standard on heat stress but this need not hold back efforts to protect employees,” says Dr. McCarthy. “Three states (California, Minnesota, and Washington) and the US military already have their own heat standards and Maryland plans to have one by 2022.

“Useful resources are available to develop a heat stress prevention program, including the relevant portion of the OSHA Technical Manual and the criteria developed by the National Institute of Occupational Safety and Health (NIOSH) for a standard on occupational exposure to heat and hot environments,” she says.5,6

Employers may be especially interested in the proven success of heat stress prevention programs, including one Dr. McCarthy helped create for a central Texas municipality. “In this example, the heat stress prevention program significantly reduced heat-related workers’ compensation costs and, within just a few years, eliminated heat-related illness during the hot season.”

Recognizing the signs

Heat-related illness includes heat cramps, heat exhaustion, and heatstroke. All three are serious; heatstroke is life-threatening. These heat illnesses may be preceded by heat rash and/or heat syncope. Other associated heat illnesses include dehydration, a breakdown of muscle called rhabdomyolysis, and kidney disease.

Heat cramps can be brought on by inadequate water and salt intake. Resting in a cool place and massaging the cramped area can help, along with drinking more water with electrolytes. Heat exhaustion calls for rest, water, and shade. The affected individual may experience extreme sweating, headache, weakness, nausea, and mood changes. Heat exhaustion must be addressed quickly as it can lead to life-threatening heatstroke. Signs of heatstroke are high body temperature, skin that is red, hot, and dry or sweaty, confusion or irrational behavior, convulsions, and fainting. At this stage, it is vital to immediately call 9-1-1 for emergency medical attention.

Through training, supervisors and employees can learn to identify the stages of heat illness and their warning signs early. Regular reminders about this information and the seriousness of heat-related illness, particularly during the hot months, will help promote health safety and a rapid response to aid employees suffering from heat’s adverse effects.

Knowing personal vulnerabilities

Employees are more vulnerable to heat-related illness if they are (1) unaccustomed to working in hot conditions, (2) required to wear personal protective equipment that inhibits heat dissipation, or (3) have personal risk factors. Personal risk factors can include:

  • Age over 60
  • Obesity (Body Mass Index over 30)
  • History of prior heat illness
  • Poor physical fitness
  • Certain medical conditions, including high blood pressure, kidney disease, heart disease, or thyroid disorder
  • Use of certain medications, such as blood pressure prescriptions, diuretics, antidepressants, and sleep aids

Employees in hot environments who meet any of these criteria should be encouraged to consult with their doctor about the risk of heat illness. They should explain their job functions, work intensity and time spent in hot temperatures, as well as any special concerns.

Downloading an app for safety

Most employees carry a smartphone, so let them know they can download a phone app that tells them when heat-related illness is a possibility, based on an hourly heat index. It also provides precautions and first aid measures. The app is the OSHA-NIOSH Heat Safety Tool from the Centers for Disease Control and Prevention (CDC). It can be downloaded for free from either the Apple Store or Google Play. Images below illustrate the useful information that is available.

Iphone image describing heat tool app.

Implementing action steps

Hierarchy inverted triangle graphic.


“We can apply the familiar hierarchy of controls to occupational heat exposure. Elimination of the exposure is most effective and personal protective equipment controls are the least effective,” says Dr. McCarthy. “The heat stress prevention program I will describe focuses primarily on engineering and administrative work practice controls.

“Controls for outdoor employees can be implemented by risk level, based on the heat index. Below 90 degrees when risk is lower, we need to prepare by providing drinking water, making medical services available, planning training efforts, and acclimatizing employees to the heat. As the heat index goes up, so does the risk of heat-related illness and prevention measures should intensify,” she says.

Between 91 and 103 degrees. Time to conduct training, schedule rest breaks in shaded areas, and set up a buddy system so each employee is partnered with another employee to help keep watch for the signs and symptoms of heat illness.

Between 103 and 115 degrees. Risk of heat illness increases. Alert employees. Limit physical exertion. Enlist personnel trained in heat stress to come on site to help monitor employees. Make sure to establish and enforce regular rest periods.

Above 115 degrees. Risk of heat illness is critical. Reschedule nonessential activities and move essential work activities to nighttime. If those controls are not adequate, stop work to avoid heat-related illness.

This chart shows these recommended steps in heat stress prevention:

Heat index graphic.

Engineering controls should also be implemented, if possible, such as decreasing air temperature with cooling booths or air conditioned break rooms, increasing ventilation or decreasing humidity with fans and exhausts, and providing shade in outdoor environments.

Heat acclimatization. When employees have either never worked in hot environments or have been away from hot environments for an extended period for any reason, heat acclimatization is necessary as a vital administrative control to prevent heat-related illness. Acclimatization gradually introduces work in hot conditions over a period of days, allowing the individual’s body to adjust. For employees who regularly work in hot temperatures but have been away, on sick leave or vacation for more than one week, follow a schedule like this:

Pie graphs showing % of heat exposure.  

For employees new to working in heat, increase exposure time in hot environmental conditions over a 7-to-14-day period, depending on environment and individual risk factors. You should never increase a new employee’s exposure to heat by more than 20 percent per day.

Enlisting employees in self-care

Concentra has created a handy tip sheet, “Prevent Heat-related Illness,” with action steps for employers on one side and self-monitoring instructions for employees on the other.

Employers and employees can work together on many of the safety recommendations, such as:

  • Understanding what heat-related illness is
  • Being able to recognize the warning signs
  • Downloading the OSHA-NIOSH Safety Tool app to handheld devices
  • Following guidance to drink water and rest in shaded areas regularly

In addition, there are self-care steps that employees can use to self-monitor adverse effects of heat on their health. Encourage at-risk employees to follow these steps:

  • Monitor your pulse rate by placing your thumb on one side of your wrist and counting the number of beats for 30 seconds. If you pulse rate is faster than 55 beats in 30 seconds, shorten the next work period by one third and maintain the same rest period.
  • Monitor your urine color. If it is anything but clear to pale yellow, you need to increase hydration by drinking more water. Avoid coffee, energy drinks, and alcohol.
  • Monitor your body’s water loss by weighing yourself at the beginning and end of each workday. If weight loss is greater than 1.5 percent, as shown in the table, increase water intake.

Water loss and weight graphic.


The completely preventable nature of this occupational exposure is a leading reason to create and implement a heat-related illness prevention program. Also, the business costs of heat stress are significant, including potential loss of life, property loss or damage, and lost productivity. Stress placed on the body by heat can lead to loss of fine motor skills, mental confusion, lethargy, and reduced motivation and performance. These consequences are real. Contact Concentra for help in creating your own program to prevent heat-related illness. 

1 “Frequently Asked Questions About Extreme Heat,” Centers for Disease Control and Prevention (CDC).
2 Finding #7 in H.R. 3668: Asuncion Valdivia Heat Illness and Fatality Prevention Act of 2019.
3 Concentra webinar: Heat Stress and Employer Readiness. May 27, 2020.  
4 “Occupational Heat Stress Gets Hearing on Capitol Hill,” Concentra, August 16, 2019.
5 OSHA Technical Manual, Section 3, Chapter 4: Heat Stress. Occupational Safety and Health Administration. 
6 Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments, The National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC). February 2016.