What Does OSHA’s Heat Rule Require? A Clause-by-Clause Guide

What Does OSHA’s Heat Rule Require? A Clause-by-Clause Guide

What does OSHA’s heat rule require? The answer currently depends on the proposed federal Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings standard, published at 89 Fed. Reg. 70,602 on 30 August 2024. The proposal would bind covered employers in general industry under proposed 29 CFR 1910.148 and employers in construction through a corresponding 29 CFR part 1926 provision. It is not yet a final rule, so employers should treat these provisions as a planning benchmark rather than an enforceable replacement for existing OSHA duties.

The proposed scope and trigger levels

The proposal is built around the heat index, which combines air temperature and relative humidity. Employers would need to identify covered work areas and determine when employees could be exposed to heat at or above the initial heat trigger of 80°F.

The high heat trigger would be a heat index of 90°F or higher. The proposed requirements become more demanding at that point. Employers would also need to account for radiant heat, air movement, workload, clothing and personal protective equipment where the heat index alone does not represent the actual risk.

This is why the OSHA proposed heat standard requirements are broader than simply posting a temperature reading. The employer must assess the work environment, select controls and preserve evidence that the controls were implemented.

The written Heat Injury and Illness Prevention Plan

Proposed 29 CFR 1910.148 would require a written Heat Injury and Illness Prevention Plan, commonly shortened to HIIPP. The plan would have to be site-specific where conditions differ between facilities, work areas or operations.

The proposed plan would identify the person responsible for administering it and describe procedures for evaluating heat hazards, implementing controls, responding to symptoms and reporting concerns. It would also address emergency response, employee training, procedures for high-heat conditions and the employer’s process for reviewing the plan.

A compliant document would therefore need more than a generic heat-stress policy. It should connect each identified work area with the applicable controls, responsible personnel, monitoring method and records. OSHA could use the written plan, training records, exposure information and interviews to determine whether the employer followed its own procedures.

The plan would also need to be available to employees and their representatives. Proposed provisions require employee participation in developing and reviewing the plan, including a way to raise concerns without retaliation.

Controls required at the initial heat trigger

At 80°F or above, the proposal would require baseline protections. These include access to suitably cool, potable drinking water in sufficient quantity for employees to drink at least 1 quart per hour for the duration of the shift.

Employers would also need to provide break areas that allow employees to cool down. The area would need to be readily accessible, shielded from direct sunlight and other heat sources, and sufficiently large for employees who need to use it. Depending on the workplace, an air-conditioned room, shaded structure or equivalent cooling location could satisfy this requirement.

The proposed standard also requires emergency response procedures, effective two-way communication and employee information about heat hazards. Training would cover heat illness symptoms, first aid, the employer’s prevention procedures and the employee’s right to report symptoms or request assistance.

For indoor operations, the assessment must consider local heat sources such as ovens, furnaces, steam lines and process equipment. OSHA indoor outdoor heat controls therefore need to address both weather-driven exposure and heat generated by the workplace itself.

Additional duties at the high heat trigger

When the heat index reaches 90°F or more, proposed 1910.148 would require additional controls. These include a minimum 15-minute preventative rest break at least every two hours, separate from meal periods and other required breaks.

The employer would also need to implement measures addressing high-heat conditions, including communication with employees, observation for signs and symptoms of heat illness, and procedures for obtaining prompt medical assistance. The precise control selected may vary by operation, but the written HIIPP must explain how the employer will apply it.

Acclimatization is a separate high-priority requirement. The proposal would require a graduated exposure approach for new employees and employees returning after an absence of more than 14 days. For a new employee, exposure would begin at no more than 20 percent of the normal duration on the first day and increase by no more than 20 percent on each subsequent day until normal exposure is reached. The employer would also need to use procedures for monitoring employees during this period.

The proposed rule recognises that acclimatization may be affected by conditions such as workload, clothing, PPE and individual susceptibility. A schedule alone would not replace the need to observe employees and respond to symptoms.

Records, training and proof of compliance

The proposal places significant weight on evidence. Employers would need to document the HIIPP, heat hazard evaluations, training and implementation of required controls. Training would have to be understandable to employees and provided to supervisors, employees and designated personnel with responsibilities under the plan.

Records should show when heat conditions were monitored, which trigger level applied, what controls were used and whether employees received required breaks and water. For indoor operations, the record should identify the heat source, affected work area and any measurements or evaluation method used.

Employers should also retain records of acclimatization schedules, employee complaints, corrective actions and heat-illness incidents. These records help demonstrate that the written plan was operational rather than merely filed in a safety manual.

The phrase 29 CFR 1910 heat illness prevention is often used to describe the proposal, but proposed 1910.148 is not currently an enforceable final standard. Until OSHA issues a final rule, employers remain subject to existing requirements, including the General Duty Clause in Section 5(a)(1) of the Occupational Safety and Health Act where recognised serious heat hazards are present.

What employers should compare now

The proposed rule is driving employers to compare current heat plans with likely federal requirements. A useful compliance comparison should test whether the existing programme contains:

• A written, site-specific HIIPP with a named administrator.
• Heat-index monitoring and a defined response at 80°F and 90°F.
• At least 1 quart of potable water per employee per hour.
• A cooling area and the proposed 15-minute, two-hour high-heat break schedule.
• Acclimatization procedures using the 20-percent progression.
• Training, emergency response, communication and recordkeeping provisions.

State-plan jurisdictions may already impose different or more protective requirements. California employers, for example, must also consider the California Division of Occupational Safety and Health outdoor and indoor heat rules. A federal proposal does not displace a state-plan requirement or a collective-bargaining obligation.

Takeaway: treat the proposal as a design specification

The practical answer to what does OSHA’s heat rule require is a documented prevention system tied to measurable thresholds. The proposed standard combines a written HIIPP, water, cooling areas, training, emergency response, acclimatization and mandatory high-heat rest breaks.

Because the rule is proposed rather than final, organisations should track OSHA’s rulemaking docket and update their plans when the agency publishes a final text. In the meantime, comparing existing controls against proposed 1910.148 is a defensible way to identify gaps before the next hot-weather season.