Heat stress is a constant threat to workers in many industries, to the extent that OSHA has regulations in place to ensure heat safety in the workplace. Specifically, OSHA’s General Duty clause requires employers to ensure their employees are safe from all identifiable hazards at the work site.

Prioritizing heat safety is also the right thing to do, as heat illness can result in long-term, even fatal effects on workers. Many researchers assert that official data doesn’t capture how many workers die every year due to heat stress on the job, but some data available confirms that dozens of workers suffer fatal heat illnesses every year.

This guide is for employers looking to improve workplace safety and ensure they are in compliance with OSHA regulations.

Risk Factors for Heat Stress

Heat stress leads to heat illness, so minimizing its impact on workers is paramount. That starts with identifying heat stress risk factors, which include:

• Heat hazards – The most obvious risk factor is the presence of heat-generating sources, like ovens, furnaces and areas where industrial machinery is outputting a lot of thermal energy into the environment (assembly lines are one example).
  Outdoor work typically means one difficult-to-avoid heat hazard: the sun. Duration of sun exposure is an essential data point to track in this case.
• Work intensity – In workplaces where moderate to intense activity is required, exertion will increase the risk of heat illness. Extended periods of work in hazardous conditions will also increase the chances of experiencing heat illness.
• Protective wear – Personal protective equipment (PPE) protects against environmental hazards but doesn’t ventilate well and will therefore trap a lot of heat.
• Certain health conditions and medications – People with certain health conditions, like cardiovascular problems, are at a higher risk of developing heat illness and more likely to experience severe symptoms.

Symptoms of Heat Related Illness

Heat illness may emerge gradually or suddenly. In most cases, there is a brief period of time during which symptoms are present and others have time to respond and help. Recognizing the symptoms of heat illness is critical for a proper emergency response then. Here’s what to look for:

• Confusion or irritability
• Loss of balance (ataxia) or weakness
• Excessive sweating or a complete lack of it
• Skin that’s clammy or pale
• Muscle cramps
• Nausea and vomiting
• A weak pulse
• Loss of consciousness

If any of the above signs are present, the worker should be removed from hazardous conditions and have treatment promptly administered.

OSHA Regulations on Heat Stress

OSHA doesn’t have any heat-specific safety regulations on the books, but the General Duty clause also applies to heat hazards. OSHA recommends employers adopt the heat safety standards published by The National Institute for Occupational Safety and Health (NIOSH).

There are several state-level and heat safety regulations, too – published in California, Colorado, Minnesota, Oregon and Washington.

There is momentum toward OSHA publishing heat-specific regulations. In fact, one was proposed in July 2024 – a rule that would require employers to enact specific safety provisions (additional breaks, additional health monitoring, etc.) when certain temperature thresholds are reached. It’s likely that OSHA will eventually publish safety regulations for heat hazards specifically, given the increased scrutiny in this area.

Heat Illness Prevention Strategies in the Workplace

There are many measures employers can implement to improve heat safety, including:

• Better hydration and nutrition guidelines – Fluid and electrolytes are lost to excessive sweating, which leads to heat illness symptoms. Replacing both is essential to warding off heat exhaustion and heat stroke, and this starts with better hydration and nutrition. Specifically, choosing hydration and electrolyte-replacing foods and drinks, like fluid-rich fruits and sports drinks. Employers are responsible for providing workers with adequate water and breaks to replenish fluids. As the temperature climbs, workers will need water breaks more frequently and will need more water to prevent heat illness.
• Monitoring workers’ health – Elevated temperatures will place additional stress on workers, and this can mean danger for workers with pre-existing health conditions.
  When conditions are hazardous, onsite safety personnel must be ready to step in and check worker vitals periodically to ensure any signs of heat illness are spotted immediately. High-risk workers with significant health conditions should be monitored closely and rotated to lighter duty, if possible.
• Preparing an emergency response – OSHA recommends employers develop heat-specifical emergency action plans (EAPs) to ensure a rapid response if heat illness does emerge.
  An EAP should outline the treatment procedures responding personnel will take if a worker experiences heat illness. EAPs outline treatment and provide an inventory of emergency response resources (and their location) and contact information for a nearby hospital or emergency room. EAPs give workers the information they need to respond quickly and effectively.
• Providing training and educational resources to employees – Once your organization has its heat safety standards in place, they must be reinforced through repeated training drills and safety-focused talk. Ultimately, all forms of workplace safety – including heat safety – are reinforced by top management, so the company’s leaders must take charge in practicing and emphasizing safety. Regular training sessions are an important way to do this.

The Right Resources and Tools Will Also Improve Workplace Heat Safety

The right heat safety resources can make the difference when a heat illness emergency occurs. These resources should be stored in a clearly marked area that all personnel are aware of. Emergency heat illness resources typically include electrolyte tablets, cool packs and wraps. Together, these can bring down dangerous body temperatures quickly and treat dehydration.

Even better, outfit workers with tools that they can use to monitor work conditions and protect themselves when working. One example is liquid crystal thermometers (LCTs) integrated into employee TWIC cards. LCTs provide an accurate temperature reading within seconds and weigh next to nothing, so they can be easily carried and stored. And for organizations on a tight budget, LCTs are low-cost solutions that encourage workers to take charge of workplace safety – something every organization will benefit from.

OSHA and Heat Stress FAQ

What is the status of OSHA’s proposed heat rule?

OSHA announced its proposed Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings rule in July 2024 and published it in the Federal Register on August 30, 2024. Public comments, an informal hearing and a post-hearing comment period followed and closed in 2025. As of October 2026 there is no final rule and no announced date for one. Until a final rule takes effect, OSHA addresses heat hazards through the General Duty Clause and any state rules that apply.

Does OSHA require a written heat illness prevention plan?

There is no federal heat standard in effect today, so OSHA does not have a rule that specifically requires a written heat plan. The proposed rule would require one, and some states with their own heat rules, such as California, already do. Even without a requirement, a written plan is the clearest way to show what your company does about heat and who is responsible for each step. Our guide to a heat illness prevention program walks through what to put in it.

What does OSHA expect employers to provide during hot weather?

OSHA’s long-running guidance comes down to water, rest and shade. Give workers cool drinking water close to the work, rest breaks that get longer and more frequent as the heat index climbs, and a shaded or cooled place to take them. Add a schedule that lets new and returning workers acclimatize, training so supervisors and crews can recognize heat illness, and an emergency plan for when someone gets sick.

How should new workers be acclimatized to the heat?

OSHA and NIOSH guidance for new workers is to start at no more than 20 percent of a normal workload or heat exposure on the first day and increase by no more than 20 percent each day after that. Workers returning after a week or more away need a ramp-up too. Many severe and fatal heat illnesses occur in workers who are new to the job, which is why acclimatization belongs in writing and not left to individual judgment.

Do heat stress cards and signs satisfy OSHA’s heat requirements?

No. No product satisfies an OSHA requirement or makes a workplace compliant. Tools like Heat Aware Cards and heat stress signs and posters support your program by keeping current conditions and the plan’s steps in front of the crew. The obligation itself is met by the employer’s plan, training, supervision and follow-through.

What should a heat emergency action plan include?

It should say who checks on workers during high heat, how to recognize heat exhaustion and heat stroke, and what to do in the first minutes: call 911, move the worker to a cooler area and start cooling right away. List where the cooling supplies are kept, the site address to give emergency responders, and who notifies a supervisor. Practice it before summer so the crew does not learn it during an emergency.