OSHA Says Businesses Must Keep Employees Safe in the Heat

Lawrence Buirse

On April 8, 2022, the Occupational Safety and Health Administration (OSHA) launched an initiative called the National Emphasis Program to protect millions of employees from heat-related illnesses.1 Currently, only a few states (i.e., California, Minnesota, Oregon, and Washington) have developed standards that specify how hot is too hot for safe working conditions. As regulations concerning heat stress and heat-related illnesses are getting more attention, many employers are implementing preventive measures to mitigate heat stress and exposure in the workplace.

But these health and safety risks don’t just apply to employees who work in outdoor heat. Employees who work in certain indoor environments are also susceptible to heat exposure and must be protected. For example, machinery in some manufacturing plants can generate high levels of heat, potentially causing indoor temperatures to climb beyond a safe level. Whether it’s rising outdoor temperatures or indoor work environments that lack sufficient climate controls, these employees are at increased risk of suffering a heat-related injury or illness.

The impact of working in hot environments

Every year, thousands of employees experience heat-related illnesses; avoidable workplace fatalities also occur due to excessive heat exposure.2 Excessive heat exposure can also exacerbate existing health problems.3 Employees with asthma, heart disease, kidney disease, and diabetes are most commonly affected.3 Employee productivity has been found to decrease 1 to 3 percent with each one-degree increase in temperature after 77 degrees.4 Increased employee turnover due to suboptimal work conditions (e.g., hot conditions without access to fluids and cooling) can result in decreased production from vacant positions, new-hire lower performance, and new-hire higher error rates.

Increases in heat-related injuries, illnesses, and fatalities, and the exacerbation of chronic illnesses can also drive up an employer’s workers’ compensation and overall health care costs. Research on 11 million workers’ compensation cases shows when temperatures reach 90 degrees F to 100 degrees F, employees are at a 7-percent to 15-percent higher risk for injury respectively compared to when temperatures are cooler.4 Thousands of these heat-related illnesses and injuries result in days away from work according to the U.S. Department of Labor.3 The following table lists some industries where employees are more prone to suffer heat-related illnesses:

Locations of excessive heat exposure
 Outdoors   Indoors
Agriculture Bakeries, Kitchens, and laundries (sources with indoor heat-generating appliances)
Construction- especially, road, roofing, and other outdoor work Electrical utilities (particularly boiler rooms) 
Construction - roofing work  Fire Services 
Landscaping  Iron and steel mills and foundries
Mail and package delivery  Manufacturing with hot local heat sources (e.g., paper products or concrete)
Oil and gas well operations Warehousing

Source: OSHA

Regulatory considerations and worksite solutions

OSHA recommends that an employer with employees exposed to high temperatures establish a heat illness prevention program. Research from OSHA concluded that nearly all heat-related illnesses and fatalities occur when employers do not adhere to preventive recommendations.3 Heat illness prevention programs must be adapted to the environment, the worksite, and exposed employees’ work duties. The success of the program depends on support from management and the employees the program protects.

Creating a worksite heat plan

The good news about occupational heat-related injuries and illnesses is that they often can be avoided. One way an employer can reduce the chances of these incidents occurring is by partnering with an occupational health provider to develop and implement a worksite prevention program. During the program development phase, Concentra® recommends instituting a H.E.A.T. plan that includes the following provisions:

  • Hydration and cooling
  • Evaluation of employees’ risks
  • Acclimatization to heat
  • Training on heat illness, first aid, and emergency response

H: Hydration and cooling

Hydration and cooling (i.e., Water. Rest. Shade.) help prevent heat-related illnesses and injuries.5 The body cools itself by:

  • Sweating (needs water to sweat)
  • Decreasing activity (rest decreases internal heat production)
  • Seeking a cooler environment (shade or air conditioning)

It is also essential to provide easy access to an unlimited supply of cool water to employees. And plan for preventive cooling breaks before heat strain occurs. Factors that add to an employee’s heat load include:

  • External hot environment
  • Clothing, including personal protective equipment (e.g., respirators, Tyvek suits)
  • Internal [body’s] heat production (i.e., physical activity/work)

E: Evaluation

The goal of medically evaluating heat-exposed employees is to screen for health factors that may increase the risk of heat illness. When evaluating employees’ health history for risk factors associated with heat illness, predisposing medical conditions and medications were found in most cases of OSHA-researched, heat-related illnesses and deaths.6 All employees who are or may be exposed to indoor or outdoor heat stress should be evaluated by an occupational health provider. An occupational health provider can provide instruction to the employee on preventive measures specific to their individual risk factors, recommend accommodations when indicated, monitor for health-related effects associated with heat stress, and provide feedback on the employers’ worksite controls.

A: Acclimatization, or gradual and repeated exposure to heat

Employees who are not acclimatized to heat stress are at high risk of severe heat-related illness. This could include newly hired employees and employees returning to work following an extended absence. The duration of heat stress exposure should be increased gradually over 7 to 14 days. New employees can be given longer and more frequent rest breaks, compared to acclimatized existing employees.

If an employee unacclimatized to the heat must work a full shift in the heat:

  • Give hourly breaks in a cool location (e.g., air-conditioned room, shade).
  • Never let the employee work alone.
  • Provide immediate evaluation and first aid if signs or symptoms of a heat-related illness occur.

T: Training

In 2021, OSHA published an advanced notice of proposed rulemaking for heat injury and illness prevention in outdoor and indoor work settings.7 OSHA is now prioritizing investigations of heat-related complaints and intervenes when they see employees performing strenuous tasks in high temperatures. Employee and supervisor training should be performed before working in the heat (e.g., during new employee orientation). For regulatory purposes, maintain records of training. And perform training in the language(s) employees understand.

After training, employees and supervisors should understand:

  • How to prevent heat illness and injury
  • How to recognize heat illness symptoms in self and coworkers
  • The importance of immediate response
  • How to respond to heat illness
  • When and how to contact emergency services
  • How to give clear directions to the work location

NIOSH heat safety tool

The National Institute on Occupational Safety and Health (NIOSH) and OSHA recommend supervisors and employees utilize the NIOSH heat safety tool to review the heat index and hourly forecast for their work location prior to work shifts to allow planning of outdoor work activities.8 The NIOSH Heat Safety Tool is a free smartphone app available in Spanish and English. The tool provides a real-time heat index and hourly forecast specific to a user’s location. There is also quick access to a list of signs and symptoms of heat illnesses with first aid and emergency response procedures.

Make heat safety a workplace priority

The impact of heat stress and exposure on productivity and overall employee health is proven. Because business operations depend on a healthy and productive workforce, employers across the spectrum must work to protect employees from the health and safety risks associated with heat stress and exposure. OSHA has brought workplace heat safety to the forefront, and now is the time for businesses to follow suit.

Concentra provides heat stress management services that can be offered as part of an employer’s medical surveillance program or with preplacement physicals. Heat safety preventive health services and resources are also available and include a heat stress screening questionnaire, which helps Concentra clinicians:

  • Identify any pre-existing health conditions that may increase the likelihood of heat-related illness or injury.
  • Recommend heat safety guidance that best preserves employee health and safety

In addition, Concentra clinicians can conduct heat stress screenings with preplacement exams and return-to-work evaluations to determine an employee’s fitness to work in a hot environment. Learn more about Concentra’s heat stress management services.


  1. National Emphasis Program – Outdoor and Indoor Heat-Related Hazards. U.S. Department of Labor Occupational Safety and Health Administration. (n.d.).
  2. U.S. Department of Labor Announces Enhanced, Expanded Measures to Protect Workers from Hazards of Extreme Heat, Indoors and Out. OSHA National News Release. (n.d.).
  3. Occupational Safety and Health Administration. (2021, October 15). Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings. Federal Register.
  4. Somanathan, E., Somanathan, R., Sudarshan, A., and Tewari, M. (2021). The Impact of Temperature on Productivity and Labor Supply: Evidence from Indian Manufacturing. Journal of Political Economy, 129(6), 1797–1827.
  5. Heat - Water. Rest. Shade. United States Department of Labor, Occupational Safety and Health Administration. (n.d.).
  6. American College of Occupational and Environmental Medicine. (n.d.). Risk Factors for Heat-related Illness in U.S. Workers: An OSHA Case Series. Journal of Occupational and Environmental Medicine.
  7. Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings Rulemaking. United States Department of Labor - Occupational Safety and Health Administration. (n.d.).
  8. OSHA-NIOSH Heat Safety Tool App. Centers for Disease Control and Prevention. (2021, June 23).