Even before summer officially began, parts of the U.S. were already experiencing extreme heat. As temperatures continue to rise, the risk of heat-related illness and fatalities in the workplace is becoming harder to ignore. Warming trends are documented across 41 states, and the frequency of heatwaves has increased significantly since the 1960s.

What was once a seasonal issue is starting to look like a near-constant occupational risk. For employers, a hotter climate brings a familiar challenge into sharper focus: how to protect workers while staying compliant with evolving safety expectations.

Heat stress has been on the workplace safety agenda for years. What's changing now is the level of scrutiny and the expectation that employers move beyond awareness to more structured, consistent action. OSHA’s proposed heat stress rule signals a shift from guidance to a more defined compliance framework, with clear expectations around monitoring, acclimatization, training and worker protection.

For many organizations, the conversation is no longer whether heat stress needs attention, but how prepared they are to manage it.

The human cost of heat stress

Heat stress occurs when the body can't cool itself enough to maintain a healthy temperature and can lead to conditions such as dehydration, heat exhaustion and heat stroke. In severe cases, it can be fatal.

While outdoor workers (e.g., in construction, oil and gas, and utilities) are among the most at-risk groups, indoor workers in environments without adequate climate control (e.g., warehouses and manufacturing plants) are also vulnerable.

Heat exposure can impair decision-making, reduce reaction times, and decrease coordination, all of which increase the risk of workplace accidents. The consequences of inadequate protection are significant, and they are a core reason why OSHA's proposed rule aims to provide a clearer, more enforceable framework for managing heat stress across industries.

What's new in the 2026 National Emphasis Program

On April 10, 2026, OSHA updated its National Emphasis Program (NEP) on outdoor and indoor heat-related hazards, replacing the 2022 version with a more targeted approach. Key changes in the 2026 NEP include:

• Updated industry targeting: OSHA added 22 new high-risk industries, removed 46 outdated ones and retained 33 from the previous program. The updated list now includes expanded coverage in construction, agriculture, warehousing, manufacturing, transportation, retail and restaurants.
  
  
• Enhanced inspection triggers: Inspections can now be initiated during National Weather Service heat advisories or warnings. Additionally, any OSHA inspection that observes heat hazards can expand in scope, even if heat wasn't the original reason for the visit.
  
  
• Improved program structure: The 2026 NEP eliminates numerical inspection goals, removes outdated guidance, and adds new appendices specifically for evaluating heat prevention programs and issuing citations with supporting weather data.

Between April 2022 and December 2024, OSHA conducted approximately 7,000 heat-related inspections, including 147 heat-related fatality inspections. The agency issued 60 heat citations under the General Duty Clause and 1,392 Hazard Alert Letters.

Understanding the proposed heat stress rule requirements

OSHA's proposed rule is designed to create a consistent, enforceable standard for managing heat risk across industries. At its core, employers must assess heat exposure regularly by evaluating ambient temperature and humidity levels, radiant heat sources, physical demands of the job, and duration of exposure.

The rule introduces the requirement for a written Heat Illness Prevention Plan (HIPP), which must outline how an organization handles key areas, including hydration, rest breaks, acclimatization and emergency response.

Importantly, the rule recognizes that not all workers face the same level of risk. New employees or workers returning after time away are considered more vulnerable, requiring a phased approach to help them build heat tolerance.

Practical steps to get started

For organizations unsure of where they stand, a practical first step is conducting a gap assessment. Preparing for OSHA's heat emphasis program may uncover the need to revise work schedules and invest in new equipment, such as heat monitoring devices and cooling systems, as well as revising work schedules.

In practice, that often means taking a closer look at how heat risk is currently evaluated day to day. Are supervisors making consistent decisions about when to pause work or rotate crews? Is there a clear threshold for action, or does it vary by site or team? Standardizing those decision points can make a meaningful difference.

It's also critical to recognize that heat tolerance varies widely between individuals. Factors such as age, preexisting health conditions, physical fitness and medications can all affect how workers are impacted. Supervisors should be trained to recognize that workers may respond differently to the same heat exposure and adjust protective measures accordingly.

It's also worth examining how well existing processes hold up under pressure. Planning for those scenarios helps ensure that controls are realistic and workable in the field.

A step-by-step approach for building a Heat Illness Prevention Plan

For organizations developing or updating their HIPP, a systematic approach ensures comprehensive coverage of all required elements.

Step 1: Conduct comprehensive heat risk assessments

Begin by establishing protocols for regular heat exposure monitoring. This goes beyond checking the temperature; organizations need to evaluate humidity, radiant heat sources, air movement and the metabolic demands of specific tasks. Consider using the Wet Bulb Globe Temperature (WBGT) index to assess heat stress at the worksite. WBGT can be measured on-site using a dedicated monitor, with readings taken regularly throughout the day as conditions change. Safety professionals can also use National Weather Service WBGT forecasts and the OSHA-NIOSH Heat Safety Tool as useful screening resources, while recognizing that regional weather data may not reflect conditions at a specific worksite.

Organizations should document their assessment methodology and establish clear trigger points for implementing protective measures. Many organizations activate their HIPP when the heat index reaches 80°F, with escalating interventions as temperatures rise.

Step 2: Develop acclimatization protocols

Acclimatization is one of the most critical—and overlooked—components of heat illness prevention. New workers, those returning from extended absences, and workers transitioning to hotter environments need time to build physiological tolerance.

Effective acclimatization programs include gradual exposure increases (typically 20% per day for new workers), extended acclimatization periods for workers with no recent heat exposure (7-14 days), closer supervision during the acclimatization period, and clear documentation of each worker's acclimatization status.

Step 3: Establish hydration and rest break standards

An organization’s HIPP must specify how it will ensure adequate hydration and rest opportunities. Cool, potable water must be readily accessible and available in sufficient quantities (approximately one quart per worker per hour). For workers experiencing prolonged or heavy sweating, electrolyte beverages or other electrolyte-containing options can also help replace nutrients lost through sweat. Employers can also consider cooling PPE, such as cooling vests, neck coverings or other wearable cooling systems, as an additional measure to help workers manage their body temperature in hot conditions.

Organizations should also establish minimum rest break frequencies that increase with heat intensity and workload as well as provide adequate shade or air conditioned spaces for breaks. These spaces must be large enough to accommodate all workers on break simultaneously.

A buddy system can help ensure workers take rest breaks and practice vigilance by monitoring colleagues for early signs of heat stress.

Step 4: Implement comprehensive training programs

Training must go beyond basic awareness to ensure workers and supervisors can recognize, respond to, and prevent heat illness.

For workers, this includes understanding the symptoms of heat illness (e.g., heat cramps, heat rash, heat exhaustion and heat stroke), alongside personal risk factors (e.g., age, medications, underlying health conditions and fitness level). Training should also reinforce the importance of hydration, rest, acclimatization and emergency response procedures.

Supervisor training builds on these efforts by equipping leaders to assess heat exposure risks, monitor workers for signs of heat stress, implement work-rest schedules, respond to emergencies and maintain documentation.

Step 5: Establish emergency response protocols

A solid HIPP should outline clear, accessible procedures for responding to heat illness emergencies. These procedures should include:

• Designated personnel trained in first aid and heat illness response;
• Communication systems for quickly summoning emergency medical services;
• Cooling protocols for treating workers experiencing heat illness; and
• Transportation plans for workers who require medical attention.

These protocols should be clearly communicated to workers and kept visible and easily accessible so they can be quickly followed in an emergency.

Step 6: Maintain required records

The proposed rule requires maintaining records for compliance verification. Organizations must document the following:

• heat exposure assessments;
• training records, which must be retained for at least three years);
• heat illness incidents;
• HIPP reviews and updates; and
• acclimatization status for at-risk workers.

The true cost of inaction

While the cost of compliance (e.g., involving new equipment, operational changes or added oversight) may seem significant, it pales in comparison to the long-term, multifaceted impact of inaction. The consequences extend far beyond direct medical expenses.

Heat-related incidents trigger a chain of operational disruptions. A single event can lead to stop-work orders, project delays and reduced crew efficiency—all of which directly threaten deadlines and budgets. When workers are physically and cognitively impaired by heat, the risk of errors increases, often resulting in costly rework and compromised quality. Furthermore, organizations that fail to act face escalating workers’ compensation claims and rising insurance premiums, reflecting a higher risk profile.

A poor safety record can also create significant reputational and contractual risk, jeopardizing relationships with clients that mandate stringent safety standards and making it harder to attract and retain skilled labor. Ultimately, the cost of adopting a reactive approach is invariably higher than the investment in a proactive prevention program.

A shift in how heat is managed

The broader direction is clear. Heat is becoming a more persistent workplace risk, and expectations around how it's managed are evolving. OSHA's proposed rule aims to create more consistent, enforceable standards to protect workers across industries.

At its core, this rule is about creating safer working conditions in environments where heat cannot be avoided. For employers, it is an opportunity to take a more proactive, structured approach by protecting workers while strengthening overall operational resilience.

Organizations that invest in comprehensive heat illness prevention programs now will be better positioned for compliance when the final rule takes effect. In the meantime, these organizations will create safer workplaces for their employees, which should always be the goal, no matter the temperature.