Heat/Heat illnesses Seasonal safety: Summer Federal agencies Occupational illnesses Heat stress Workplace exposures

Keep workers safe during hazardous heat

7 things you should know

Photo: Minnesota Department of Transportation/flickr

For many people in the United States, summertime means working in high temperatures. Excessive heat increases their risk of a heat-related illness or injury. Here are seven facts about heat exposure and how you can help protect workers.


OSHA has no standard on heat, but the General Duty Clause may apply.

The agency is developing a standard on heat-related injury and illness prevention in outdoor and indoor work settings. A proposed rule could be published by the end of the year, acting Labor Secretary Julie Su said during a May 1 congressional hearing.

Until then, OSHA can cite employers for heat-related violations under the General Duty Clause. To do so, the agency must prove:

  1. The employer failed to keep the workplace free of a hazard to which its employees were exposed.
  2. The hazard was recognized.
  3. The hazard was causing or was likely to cause death or serious physical harm.
  4. A feasible and useful method to correct the hazard was available.
More of OSHA's most interesting cases

The General Duty Clause at work

OSHA considers it one of its “Most Interesting Cases”: A 24-year-old employee died in July 2022 while working on a project for a Louisiana-based archaeological and historic preservation company. It was her first day on the job.

As officials described it during a Technical Session at the 2023 NSC Safety Congress and Expo in New Orleans, the heat index climbed as high as 107° F during the six-hour survey project. The company had no acclimatization process for employees. Additionally, supervisors and workers didn’t have the knowledge and training to recognize the symptoms of a heat-related illness.

The company’s heat safety plan for the site only briefly mentioned rest “when needed” and didn’t include a work/rest schedule. No provisions were made for a cool rest area. OSHA cited the company under the General Duty Clause (Section 5(a)(1) of the Occupational Safety and Health Act of 1970).

Go to More of OSHA's most interesting cases to read more about this incident.


States may have their own laws.

At press time, five states had some form of a heat exposure standard: California, Colorado, Minnesota, Oregon and Washington.

However, requirements may differ. For instance, Colorado’s heat standard covers agricultural workers, and Minnesota’s applies to indoor places of employment.


Warnings are issued based on the heat index.

The heat index is “an accurate measure of how hot it really feels when the effects of humidity are added to high temperature,” according to the National Weather Service.

NWS advises “caution” when the heat index reaches 80° F and “extreme caution” at 90° F. A heat index between 105° F and 129° F gets a “danger” warning, and any degree above 129° F elicits an “extreme danger” warning.

National Weather Service heat index table

The California Division of Occupational Safety and Health, or Cal/OSHA, has its own heat illness prevention standard, with requirements including providing access to water and shade beginning when the temperature is 80° F or higher.

OSHA and NIOSH have developed a heat safety app intended to help employers and workers plan outdoor work activities “based on how hot it feels throughout the day.” It includes a real-time heat index and location-specific hourly forecasts, as well as recommendations for staying safe. Go to cdc.gov to learn more.


A heat-related illness prevention plan is best when customized.

A heat-related illness prevention plan “should be tailored as much as possible to the organization’s specific circumstances by considering work process, the work environment and the workers involved,” says CPWR – The Center for Construction Research and Training.

The development of that plan should involve workers at all levels of the organization to ensure “it reflects the reality of the jobsite.”

As one example, in its heat standard, Cal/OSHA requires employers to:

  • Develop and implement a written heat-related illness prevention plan
  • Train workers and supervisors
  • Supply water
  • Provide access to shade and encourage rest breaks

CPWR recommends designating someone within the organization to implement the plan. That person should have stop-work authority to address unsafe practices.

Heat-related illness vs. injury: What’s the difference?

The terms “heat-related illness” and “heat-related injury” can be confusing. OSHA uses these definitions:

Heat-related illness – an adverse clinical health outcome that occurs as a result of exposure to hazardous heat.

Heat-related injury – an injury linked to heat exposure that isn’t considered one of the typical symptoms of a heat-related illness. Example: a fall or cut.


Knowing the symptoms of a heat-related illness can save a life.

A significant part of employee training is being able to recognize the symptoms of a heat-related illness. They are:

Heat exhaustion


  • Feeling faint or dizzy
  • Excessive sweating
  • Cool, pale, clammy skin
  • Nausea or vomiting
  • Rapid, weak pulse
  • Muscle cramps


  • Get to a cool, air-conditioned place.
  • Drink water if fully conscious.
  • Take a cool shower.
  • Use a cold compress.


  • Throbbing headache
  • No sweating
  • Body temperature above 103° F
  • Red, hot, dry skin
  • Rapid, strong pulse
  • Loss of consciousness


  • Call 911.
  • Take immediate action to cool the worker until help arrives.
Sources: Weather.gov and SacramentoReady.org

“Report symptoms promptly to a supervisor and know how to respond in an emergency, including first aid, cooling procedures and how to direct emergency responders to your location,” CPWR says in a hazard alert on heat. “If you notice possible signs of heat exhaustion or heatstroke in yourself or a co-worker, begin cooling the person down and call 911 immediately.”


Staying hydrated can help prevent a heat-related illness ...

A rule of thumb for employees when working in the heat: Drink 8 ounces of water three to four times an hour. Don’t wait until you’re thirsty to start drinking water. Also, avoid alcohol and caffeinated or sugary soft drinks.

For work lasting longer than two hours, OSHA says employers should provide sports drinks or other beverages containing electrolytes.

“Workers lose salt and other electrolytes when they sweat,” the agency says. “Substantial loss of electrolytes can cause muscle cramps and other dangerous health problems. Water cannot replace electrolytes.”


... and so can rest and shade.

Provide breaks for employees working in the heat. How long those breaks should last “depends on several factors,” OSHA says. They include:

  • Environmental heat, meaning the heat produced by the worker’s surroundings.
  • A worker’s exertion level – how hard the worker is pushing him or herself.
  • Personal risk factors, such as how acclimatized workers are to the heat, level of physical fitness, health conditions, medications or clothing/personal protective equipment worn by the employee – any of these risk factors can prolong the time needed to recover.

The length and frequency of rest breaks should increase as the temperature rises. “In general, workers should be taking hourly breaks (when the wet bulb globe temperature is 70° F or higher),” OSHA says.

And these breaks should take place in a shaded, air-conditioned or cool area.

“If workers rest in a cooler location, they will be ready to resume work more quickly,” OSHA says. “Breaks should last longer if there is no cool location for workers to rest.”

Employees should remove PPE or extra clothing – if safe to do so – to help them cool off during their breaks.

“Some workers might be tempted to skip breaks,” OSHA says. “In hot conditions, skipping breaks is not safe!”

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