OSHA defines a heat priority day as a day when the heat index is expected to be 80°F or higher, and programmed inspections may occur when the National Weather Service has issued a local heat warning or advisory.
Heat exposure is one of the most preventable workplace hazards, yet it continues to cause serious illness, hospitalization, lost productivity, and fatalities across the United States.
We solve this through heat illness prevention, which is most effective when built into daily operations. A strong program does not wait for someone to feel faint before acting. It anticipates heat stress, reduces exposure, acclimatizes workers, trains supervisors, empowers employees to report symptoms, and responds quickly when warning signs appear.
For employers, the message for 2026 is clear: heat injury prevention can no longer be treated as a seasonal reminder or a poster in the breakroom. It should be managed as a formal safety and health program.
Here’s how to build one.
What Changed in 2026?
On April 10, 2026, OSHA updated its National Emphasis Program for Outdoor and Indoor Heat-Related Hazards, Directive CPL 03-00-024. The updated program is effective immediately and is scheduled to remain in place for five years.
The update:
- Added new citation guidance
- Revised targeted industries
- Strengthened instructions for documenting heat-related inspections
- Eliminated the former numerical inspection goal, and
- Introduced reorganized appendices for evaluating heat programs and citation guidance
This is important because OSHA compliance officers may expand inspections when they see evidence of heat-related hazards, such as workers exposed to high temperatures without adequate training, acclimatization, or access to water, rest, and shade.
The federal heat standard is still separate from the NEP. To fix this, OSHA published its proposed rule, Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings, in August 2024. As of May 2026, OSHA’s rulemaking page still describes the rule as proposed rather than final.
Why Heat Injury Prevention Matters
Millions of workers are exposed to heat on the job, and OSHA continues to emphasize that heat-related illness can occur indoors or outdoors, during heat waves or ordinary workdays, and in any season when the right conditions are present.
Additionally, many outdoor heat-related deaths occur early in a worker’s exposure to hot conditions because the body needs time to build heat tolerance through acclimatization.
It is also important to note that heat illness is not limited to roofing, road work, or agriculture.
OSHA identifies heat exposure risks in outdoor industries such as agriculture, construction, roofing, landscaping, mail and package delivery, and oil and gas operations, as well as indoor settings such as bakeries, kitchens, laundries, boiler rooms, fire service, foundries, steel mills, manufacturing facilities with furnaces or hot processes, and warehousing.
The problem is that many employers assume workplace heat risk is created by the temperature on a weather app. It’s way more than that.
OSHA identifies several contributing factors:
- air temperature
- humidity
- sunlight
- air speed
- heat-generating equipment
- workload
- protective clothing or gear, and
- individual health factors
Employers must account for both environmental heat and metabolic heat generated by physical work.
This is why a warehouse, kitchen, laundry, foundry, manufacturing floor, utility room, construction site, delivery route, or agricultural field can become dangerous even when conditions do not appear extreme.
OSHA’s Technical Manual explains that heat stress is the net heat load on the worker, including exertion, environment, and clothing, while heat strain is the body’s physiological response. When the body cannot cool itself effectively, heat-related illness or death can occur.
But how can acclimatization help?
Acclimatization: The First Week Is Critical
One of the most important heat injury prevention strategies is acclimatization.
New workers, temporary workers, workers returning after time away, and employees assigned to hotter or more physically demanding tasks need time to adapt.
CDC/NIOSH recommends gradually increasing exposure over 7 to 14 days.
- For new workers, exposure should be no more than 20% on day one, increasing by no more than 20% each additional day.
- For workers who already have experience with the job, the suggested schedule is no more than 50% exposure on day one, 60% on day two, 80% on day three, and 100% on day four.
This matters because a worker can be highly motivated, physically strong, and experienced in the industry but still be unacclimatized to current conditions. A worker returning after vacation, illness, a cooler assignment, or a seasonal break may need a re-entry plan.
Employers should also be alert during the first heat wave of the season, when even experienced workers may not yet be heat-adapted.
A strong acclimatization program should include shorter shifts or reduced exposure, lighter workloads, closer supervision, more frequent rest breaks, scheduled hydration, buddy checks, and clear authority for supervisors to slow or stop work when symptoms appear.
What OSHA Will Look For in a Heat Program
OSHA compliance officers are directed to consider whether:
- The employer has a written or verbal heat program that is effectively communicated
- How the employer monitors ambient temperature and work exertion
- Whether cool water is accessible
- Whether hydration breaks and scheduled breaks are allowed
- Whether shade is available, and
- Whether new and returning workers are given time to acclimatize
OSHA also directs attention to administrative controls, training, employee and supervisor understanding, and whether a designated heat safety representative is properly managing the program.
In practical terms, employers should be ready to answer these questions:
- Does the company have a heat illness prevention plan?
- Who is responsible for implementing it each day?
- How are heat conditions monitored?
- How are high-risk tasks identified?
- How are water, rest, shade, and cooling provided?
- How are new and returning workers acclimatized?
- How are employees trained to recognize symptoms?
- How are supervisors trained to respond?
- How are heat-related incidents documented and reviewed?
- How does the company verify that controls are working?
These questions should be addressed before the hot season begins, not after an incident occurs.
Building a 2026 Heat Injury Prevention Program
A strong heat injury prevention program begins with leadership commitment.
Employers should identify a heat safety coordinator or responsible manager, define supervisor duties, and give supervisors authority to adjust work when conditions become unsafe.
The proposed OSHA heat rule would require employers to develop a site-specific Heat Injury and Illness Prevention Plan, or HIIPP, to evaluate and control heat hazards. OSHA’s proposed rule would also require employee input, heat hazard identification, emergency response procedures, training, and recordkeeping.
The plan should include both outdoor and indoor operations.
- Outdoor work should account for direct sunlight, reflected heat from asphalt or concrete, limited shade, humidity, and remote work locations.
- Indoor work should account for ovens, furnaces, steam, dryers, poor air movement, radiant heat sources, loading docks, mezzanines, boiler rooms, and areas where heat accumulates.
How To Monitor Heat Conditions
Employers should use objective methods to monitor heat risk.
OSHA and NIOSH provide a Heat Safety Tool app that uses heat index and local forecasts to help plan outdoor work, but NIOSH notes that wet bulb globe temperature, or WBGT, is preferred when available because it better accounts for heat stress factors.
The heat index is useful, but it was designed for shady, light wind conditions, and full sun can increase heat index values by up to 15°F.
OSHA recommends WBGT monitoring because it accounts for air temperature, humidity, radiant heat, and wind. A WBGT meter should be placed near the actual work location, such as in direct sunlight if employees are working in direct sunlight.
Use Engineering Controls First
Engineering controls reduce heat exposure at the source.
OSHA’s 2026 NEP identifies several engineering controls, including:
- air conditioning
- increased ventilation
- cooling fans
- local exhaust ventilation where heat is produced
- reflective shields to block radiant heat
- insulation of hot surfaces
- repair of leaking steam, and
- shade for outdoor work sites
Indoor employers should pay particular attention to ventilation, radiant heat, humidity, and localized heat sources.
Outdoor employers should plan shade structures, cooling stations, mobile cooling options, and access to air-conditioned vehicles or trailers where appropriate.
Adjust Work Practices
Administrative controls are also essential.
OSHA’s NEP identifies scheduling hot jobs during cooler parts of the day, scheduling maintenance and repairs during cooler seasons when possible, providing cool drinking water, permitting frequent rest and water breaks, using relief workers, reducing physical demands, using work/rest schedules, and gradually increasing workload for new and returning workers.
Work practice controls should be specific. “Take breaks as needed” is weaker than a plan that defines when breaks occur, where workers recover, who monitors symptoms, and how supervisors respond when the heat index, WBGT, workload, or PPE burden increases.
Provide Water, Rest, and Shade
Hydration must be easy, continuous, and encouraged.
OSHA’s heat prevention poster advises workers to drink cool water even if they are not thirsty, at least one cup every 20 minutes. Employers should make water readily accessible near the work area and should not create barriers that discourage hydration, such as production pressure, distant water stations, or lack of bathroom access.
Rest areas should be shaded, cooled, or otherwise removed from heat sources. Rest breaks should be long enough for recovery and adjusted based on temperature, humidity, workload, sun exposure, clothing, PPE, and worker acclimatization.
Train Workers and Supervisors
Training should be practical, repeated, and understandable.
Workers should know the signs and symptoms of heat exhaustion, heat stroke, heat cramps, heat syncope, heat rash, and rhabdomyolysis. They should also know how to report symptoms, how to access water and rest areas, what the acclimatization plan requires, and when to seek emergency help.
Supervisors need more detailed training.
They should understand heat monitoring, work/rest schedules, job rotation, emergency response, documentation, and the importance of taking all symptoms seriously.
CDC/NIOSH recommends training supervisors and workers, using a buddy system, encouraging self-monitoring, providing cool potable water near the work area, using heat alert programs, and instituting acclimatization plans.
Emergency Response: Do Not Wait
Heat stroke is a medical emergency.
OSHA identifies abnormal thinking or behavior, slurred speech, seizures, and loss of consciousness as emergency warning signs. When these occur, employers should call 911 immediately, cool the worker right away with water or ice, and stay with the worker until help arrives.
Every heat injury prevention program should include an emergency response plan that answers practical questions:
- Who calls 911?
- Who starts cooling?
- Where is ice or cold water located?
- Who meets emergency responders?
- How will EMS find the worker on a large site, farm, warehouse, roof, or remote location?
- Who documents the event?
- Who notifies management?
- Who evaluates whether other workers are at risk?
Employers should also remember OSHA reporting requirements. Work-related fatalities must be reported to OSHA within eight hours, and work-related inpatient hospitalizations, amputations, or loss of an eye must be reported within 24 hours.
Personal Risk Factors and Medical Confidentiality
Some workers may be more vulnerable to heat illness due to medical conditions, medications, fitness level, prior heat illness, alcohol or drug use, dehydration, sleep deprivation, or inability to acclimatize.
OSHA identifies obesity, diabetes, high blood pressure, heart disease, lower physical fitness, certain medications, alcohol use, and illicit drug use as examples of personal risk factors, while emphasizing that employers should make jobs safe for all employees and protect the confidentiality of workers’ health information.
This is where occupational medicine can provide important support.
Employers should not ask supervisors to make medical judgments or collect unnecessary private health information.
Instead, employers can use occupational medicine resources to support confidential medical evaluations, fitness-for-duty decisions when appropriate, return-to-work planning after heat illness, medication-related education, and medical surveillance programs for high-risk environments.
Start your customized health plan to meet your business needs and keep your employees healthy and safe.
Our Occupational Medicine Team will develop a custom plan for your company. You may need a combination of services related to:
We understand the impact that lost time, limited duty, and medical costs have on the company and the employee. So, work with an occupational medicine provider that can be staffed On-Site or have a mobile health clinic come to reduce employee downtime away from the office.
We also have a strong understanding of the OSHA recordkeeping rule and how certain medical diagnosis and treatments impact your OSHA 300 log.
For more information, contact us at 800.551.9816 or info@cnsoccmed.com.
