OSHA Heat Rule: What Employers Should Know

Heat waves and advisories are becoming fiercer and more relentless than years past. Despite advanced technology that offers more accurate forecasting and buildings with widespread access to air conditioning, heat remains the deadliest weather-related threat in the U.S., claiming an average of 40 lives annually since 2011.

The Occupational Safety and Health Administration (OSHA) has been aware of heat risk to workers for years but has lacked written guidance for employers beyond the General Duty Clause of providing a work environment free from hazards. While OSHA's proposed rule has not yet become a federal heat standard, it will cover hazardous heat exposure for both indoor workers without climate-controlled environments (furnaces, machinery, hot tar ovens, etc.) and employees working outdoors. Here are the key components that employers should prepare for now.

Please note: several states have already issued their own heat illness and injury prevention laws to protect workers exposed to severe heat. Please contact your Stratus HR rep for more details.

OSHA Rules on Heat: Will My Company Be Subject to the OSHA Heat Standard?

Employers in all general industry, construction, maritime, and agriculture sectors under OSHA jurisdiction may be impacted by proposed OSHA heat regulations that apply to both indoor workplaces and outdoor work, particularly if employees experience any of the following heat hazards:

• Work outdoors in warm weather
• Run or work near ovens, fires, hot tar, or anything that produces extreme heat
• Perform strenuous physical activity
• Wear heavy or non-breathable work clothes

To prevent and reduce heat-related injuries, employers should prepare now to adjust their work environment with the following compliance requirements.

1. Create a Heat Injury and Illness Prevention Plan (HIIPP)

The first step for compliance with the OSHA heat stress standard rule is to develop a site-specific Heat Injury and Illness Prevention Plan (HIIPP), a heat safety plan tied to heat illness prevention for each worksite, with training, monitoring, and emergency response procedures to address heat risk.

Your plan should include the following:

• Who will provide daily oversight as the designated heat safety coordinator
• Your strategy to help new workers acclimate to the heat
• Who will supervise new employees and workers returning from extended leave
• How to determine whether first aid is adequate
• Protocol for seeking additional medical assistance when first aid does not suffice
• Engineering controls and work practices that will reduce heat stress
• How heat stress will be measured
• What to do when the National Weather Service issues a heat advisory or warning
• How you will determine whether heat stress is hazardous through regular heat risk assessments and what control measures will be used
• If employees wear vapor barrier clothing, how to evaluate heat stress hazards related to clothing and how to protect those workers
• What heat safety training will be provided to employees and supervisors, including preventing heat stress
• Emergency response plan, including emergency contact information, procedures for medical assistance, methods for cooling affected employees, and steps to protect workers from heat illness

Companies with 10+ employees must have the plan in writing and make it accessible to all workers in a language they understand. Businesses with fewer than 10 employees can communicate their plan orally. Employers must also ensure workers have access to clean drinking water, scheduled rest breaks in shaded or cool areas, and designated cooling spaces for recovery from heat exposure.

Non-managerial employees should be involved in HIIPP development and updates and review the plan annually or after significant heat-related incidents. These heat illness prevention plans should also be reevaluated after a recordable heat illness. If you have multiple similar worksites, you can create a unified HIIPP with site-specific heat risk evaluations and site-specific details.

2. Designate a Day-to-Day Heat Supervisor

The second step to comply with OSHA’s proposed heat rule is to determine who at the worksite will be responsible throughout the day for supporting occupational safety and health compliance and helping enforce heat safety by monitoring conditions and ensuring employees are adhering to the heat plan. This should be a responsible person working on-site, such as a foreman, jobsite supervisor, plant manager, safety director, or anyone who has received proper training in occupational safety.

To be properly trained, your Heat Supervisor should know how to:

• Assess heat hazards and identify high-risk areas and tasks
• Monitor heat conditions by tracking local heat index forecasts or measuring internal heat metrics
• Control heat hazards, particularly during peak heat periods
• Recognize when employees are displaying early symptoms of heat stress, such as heat exhaustion or heat stroke
• Administer first aid for heat-related illnesses
• Activate emergency medical services

Non-managerial employees should participate in identifying heat hazards and developing monitoring plans. The Heat Supervisor should also know how to report any heat-related conditions or signs/symptoms of heat-related illnesses that employees may have developed while on the job.

3. Be Prepared with Intervention Methods

Whether working indoors or outdoors, employers should monitor heat levels, track the heat index, and implement specific control measures based on local conditions once the initial and/or high heat triggers are reached.

What are the Heat Trigger Thresholds?

There are two primary heat thresholds that trigger action: the initial heat trigger and the high heat trigger.

1. Initial Heat Trigger: 80°F heat index or equivalent

When employees are exposed to heat at or above 80°F (or equivalent), initial protection measures apply. Protections only apply during the period that the temperature remains at or above 80°F.

2. High Heat Trigger: 90°F heat index or equivalent

Additional protection measures such as more frequent rest breaks apply if exposure reaches the high heat trigger of at least 90°F (or equivalent).

These protections are only required during the period of heat triggers. For example, an employee working outdoors from 7A.M. - 3P.M. who only experiences a heat trigger from 1P.M. - 3P.M., during peak heat hours, would only require protection from 1P.M. - 3P.M.

What Protection Measures and Resources Should Be Available for Heat Triggers?

The following requirements must be provided or implemented at no cost to employees as part of the proposed OSHA heat rule.

Drinking Water

The proposed rule emphasizes access to toilet facilities and sufficient potable water to prevent dehydration and heat-related illnesses. Water should be accessible and placed close to work areas using water coolers, jugs, or bottled water, and means for drinking (cups or refillable bottles).

Water must be suitably cool to encourage consumption and reduce heat strain, aligning with existing field sanitation standards. This could be met by using taps, coolers, or ice to maintain cool temperatures. While electrolyte supplements are recommended, they are not mandatory and do not replace the need for water.

Employers must provide at least one quart of water per employee per hour, ensuring continuous availability, and remind employees about the importance of drinking water to prevent heat-related illnesses.

Rest Breaks

You must allow and encourage employees to take paid rest breaks as needed to prevent overheating. Employees paid on a piece-rate basis must be paid at their normal rate of pay while on break to not penalize them for taking a break.

Break areas must be readily accessible and as close as possible to minimize time and effort to access them.

While the mandated minimum rest break is 15 minutes every two hours for circumstances at or above the high heat trigger of 90°F, these are mandatory rest breaks. Breaks should be taken in shaded or cool areas, with designated cooling spaces available so employees can recover from heat exposure, and employers must ensure access to clean drinking water. Employees can also take additional unscheduled rest breaks based on their judgment to manage heat strain.

Break Areas

An adequate break area is where employees can hydrate, remove personal protective equipment (PPE), and cool down. Break areas must accommodate all employees on break and be accessible to the work area.

Outdoor break areas must offer either shade (artificial or natural) or air conditioning if enclosed and be large enough to allow ventilation and airflow without forcing employees to stand too closely together.

Indoor break areas must be an unlocked room with air-conditioning, a fan, or a dehumidifier that allows employees to cool down and hydrate.

Indoor Work Area Controls

When temperatures meet or exceed the initial heat triggers, you must increase air movement and, if necessary, dehumidification, air conditioning, or measures to reduce exposure to radiant heat to help reduce environmental heat in indoor workplaces. This may include using fans, air conditioning units, or radiant heat barriers, but fan use should not simply circulate hot air when cooling is needed.

Evaluation of Fan Use

When temperatures exceed 102°F, you must evaluate humidity levels and discontinue fan use if deemed harmful. (Studies indicate that at temperatures above 102°F, fan use can be detrimental depending on humidity.)

Acclimatization Protocol

Employers must implement a heat acclimatization protocol for new and returning workers in warm or hot environments exposed to heat at or above the initial heat trigger of 80°F. This is essential because occupational risk factors include strenuous work, lack of acclimatization, and clothing that traps body heat. They can either follow a detailed acclimatization plan or gradually increase workload in hot environments over 1–2 weeks.

If opting for gradual exposure, employers must compensate employees for a full shift, even if actual work is reduced. This ensures employees adapt to heat safely while still receiving full pay and potential alternative work during acclimatization. Many heat-related fatalities occur in the first few days before workers acclimatize.

Personal Protective Equipment (PPE)

Employers are not required to offer cooling PPE to employees. However, if it is offered, the cooling properties must be maintained.

Effective Communication

Employers must maintain effective communication methods to allow both employer-to-employee and employee-to-employer interactions, especially for reporting heat-related symptoms. These may include voice, hand signals, or electronic means like handheld transceivers or phones.

In addition, employers should establish regular communication intervals. When employees are required to initiate contact, the employer must follow up if no communication is received. This requirement extends to employees working alone, necessitating appropriate communication systems for their safety.

Observation for Signs and Symptoms

Recognizing heat illness symptoms early is crucial to prevent serious conditions, and observation helps identify heat stress symptoms before they worsen. The standard includes three main methods for observation:

1. Buddy System: Employees pair up to watch for each other’s symptoms.
2. Supervisor/Coordinator Observation: Supervisors or coordinators monitor up to 20 employees for symptoms and, when appropriate under the employer’s procedures, body temperature.
3. Communication Every 2 Hours: Employers must ensure regular two-way communication with employees working alone and check in every two hours.

The proposed standard emphasizes the need for effective communication and training on recognizing heat-related illness and emergencies. Employers must act on observed symptoms and provide proper training to ensure safety and prevent severe heat-related health issues.

Hazard Alerts

Employers must issue a hazard alert to employees before a shift or when heat conditions reach the high heat trigger as part of their heat safety protocols during hot weather and heat waves. This alert aims to prevent heat-related illnesses by informing employees about heat hazards, preventive measures, and emergency procedures.

Effective hazard alerts should include information on hydration, rest breaks, and emergency responses. The alert can be delivered through various methods, including signage, electronic communication, or verbal announcements, and must be in languages and at a literacy level for all employees to understand.

Excessively High Heat Areas

Employers must post warning signs in indoor work settings where temperatures regularly exceed 120°F. These signs must be visible, legible, and understandable to alert employees to the extreme heat hazards. They should include danger warnings, health risks, and safety precautions.

4. Implement Employee/Supervisor Training

Employees and supervisors must receive initial and ongoing heat safety training, and employers must provide heat safety training before exposure begins as a central part of heat illness prevention. Extreme heat is the leading cause of weather-related deaths in the United States, and more than 33,000 work-related heat injuries and illnesses were reported from 2011 to 2022, though the true total is likely higher. Training must cover personal risk factors, signs of heat-related illnesses, and emergency response procedures, with annual refreshers aimed at preventing heat stress and supplemental sessions as needed for policy changes, role updates, or heat-related incidents.

Materials for training must be understandable to all employees and provide opportunities for questions.

5. Maintain Record keeping

Employers with indoor work areas where heat may reach or exceed the initial heat trigger must maintain records of onsite indoor temperature measurements for at least six months. This record keeping helps OSHA verify compliance, identify temperature trends, and document occupational heat exposure in indoor workplaces during heat-related incidents.

Who Is Exempt from OSHA's Heat Rule Compliance?

While many employers will require compliance, there are a few specified exemption categories for employers within OSHA’s jurisdiction. Remember, states with their own OSHA-approved plans may impose stricter new OSHA heat regulations than the federal rule.

Employees with Minimal Work Activities

Employees who perform activities with no reasonable expectation of exposure to high heat or those under 15 minutes in any hour at the heat trigger are exempt from this rule.

Firefighting/Emergency Response

Organizations focused on firefighting or certain emergency activities are exempt due to separate standards covering these areas.

Indoor Air-Conditioned Work

Activities in consistently air-conditioned environments below 80°F are exempt.

Telework

Work performed from home or chosen remote locations are exempt.

Sedentary Indoor Work

Sedentary activities like sitting, occasional brief walking, or lifting lightweight objects in indoor settings are exempt.

Short Exposure Periods

Work involving heat exposure over short periods and work conducted in air-conditioned vehicles are also considered exempt under strict conditions.

When Does OSHA's Heat Safety Rule Go into Effect?

OSHA's proposed heat standard rolled out during the Biden administration and had a hearing and post-hearing comment session that finalized in September of 2025. Currently, there is speculation that the proposed federal heat standard might be scaled back by the Trump administration, perhaps with a site-specific Heat Injury and Illness Prevention Plan. Until then, OSHA addresses heat-related hazards through the general duty clause and the National Emphasis Program, which was extended in April 2026 for proactive inspections in high-risk industries during heat waves. Under Section 5(a)(1) of the OSH Act, employers must provide a workplace free from recognized hazards that could cause death or serious harm, and OSHA can cite employers for recognized heat hazards before a formal standard is finalized.

For help with preparing for these new regulations, please contact your Stratus HR representative.

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Sources:

https://www.osha.gov/sites/default/files/Heat-NPRM-Final-Background-to-Sum-Ex.pdf https://www.osha.gov/heat-exposure/resources
https://www.osha.gov/sites/default/files/enforcement/directives/CPL_03-00-024_0.pdf