Quick Answer
OSHA's proposed Heat Injury and Illness Prevention rule would require most U.S. employers with workers exposed to indoor or outdoor heat to maintain a written heat plan, provide water and paid rest breaks, monitor heat-index conditions, acclimatize new and returning workers, and train staff on heat illness. The rule is in rulemaking and not yet final, but OSHA already enforces heat hazards today under the General Duty Clause — so employers should prepare now rather than wait.
Why it matters
Heat is now the deadliest weather hazard in the United States, and workplace heat injuries are consistently underreported. For small businesses, a single heat-related hospitalization can trigger an OSHA inspection, a workers' compensation claim, and lost productivity across an entire crew — often during the busiest weeks of the year.
Even before the proposed rule is finalized, OSHA's National Emphasis Program on heat means warehouses, construction sites, restaurants, and manufacturing plants are actively being inspected. Employers who already have a written heat plan, documented training, and a paid rest-break protocol are dramatically better positioned — both for compliance and for keeping people safe.
Detailed guide
What the proposed OSHA heat rule actually is
OSHA's Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings is a proposed federal standard currently moving through rulemaking. It would be the first OSHA standard written specifically for heat. Until it is finalized, OSHA continues to cite employers for heat hazards under the General Duty Clause (Section 5(a)(1) of the OSH Act), which requires employers to keep workplaces free of recognized serious hazards.
The proposal applies broadly: most general industry, construction, maritime, and agriculture employers with employees exposed to heat — indoors or outdoors — would be covered. Short, incidental exposures (under roughly 15 minutes in any 60-minute period) and certain remote or climate-controlled work are excluded.
The two heat-index triggers employers should plan around
The proposed rule organizes employer obligations around two heat-index thresholds. Employers should treat these as planning anchors even before the rule is final, because they reflect how OSHA inspectors already evaluate heat hazards.
Initial heat trigger — around 80°F (27°C) heat index
Provide cool drinking water (at least 1 quart per employee per hour), allow and encourage paid rest breaks as needed, designate shaded or air-conditioned break areas, and make a written heat plan available to employees in a language they understand.
High heat trigger — around 90°F (32°C) heat index
Add mandatory paid rest breaks (typically 15 minutes every 2 hours), implement a buddy system or supervisor check-in, issue hazard alerts to staff at the start of the shift, and follow a formal acclimatization protocol for new employees and anyone returning after more than 14 days away.
Who would be covered — and where small employers fit in
The proposed rule does not exempt small businesses. A 6-person landscaping crew, a 12-person restaurant kitchen, a 25-person warehouse, or a single-site manufacturer would all be expected to maintain a written plan and follow the same triggers as large employers. The depth of documentation can scale to the size of the operation, but the core obligations do not disappear at a head-count threshold.
Industries with the highest exposure — construction, warehousing and logistics, agriculture, restaurants and commercial kitchens, manufacturing, roofing, and delivery — should expect closer scrutiny under OSHA's ongoing heat National Emphasis Program even while the rule is still proposed.
What employers should do now to prepare
The single highest-leverage step is to put a written heat plan in place before the next hot stretch. A defensible plan names a designated heat-safety coordinator, identifies the heat-index source you monitor (NOAA / weather.gov is standard), lists the specific actions taken at each trigger, and is shared with employees in a language they understand.
From there, focus on the four operational pillars OSHA inspectors consistently look for: water access, rest break enforcement, shaded or cooled rest areas, and a documented acclimatization schedule for new and returning workers. Training records and daily heat-index logs are what turn a good practice into a defensible one.
State rules that already go further
Several states have enforceable heat standards today that meet or exceed what the federal proposal contemplates, including California, Washington, Oregon, Colorado, Minnesota, Nevada, and Maryland. Employers operating in those states should plan to the stricter of the state rule or the federal expectation. Multi-state employers should standardize to the strictest applicable rule rather than maintain parallel programs.
Practical checklist
Actionable steps employers can implement immediately.
- Designate a heat-safety coordinator and document who is responsible for monitoring conditions each shift.
- Write a one-page heat illness prevention plan that names your heat-index source and the actions taken at the 80°F and 90°F triggers.
- Provide cool drinking water within easy access of every work area — at least 1 quart per employee per hour.
- Establish a shaded or air-conditioned rest area large enough for the number of employees on break at one time.
- Implement an acclimatization schedule that gradually increases heat exposure over 7–14 days for new hires and anyone returning after 14+ days away.
- Schedule paid rest breaks at the high-heat trigger (typically 15 minutes every 2 hours) and track them.
- Train all employees and supervisors on heat illness symptoms, the buddy system, and emergency response — and keep the training records.
- Log daily heat-index readings so you can show inspectors what you knew and when.
- Post a one-page emergency response procedure where staff actually work, with first-aid steps and the manager on call.
- Review and update the plan annually, after any heat incident, and any time the work, site, or workforce changes meaningfully.
Common mistakes
Treating 'take a break if you need one' as a policy
Self-directed breaks are not enforcement-defensible at the high-heat trigger. Inspectors expect scheduled, paid rest breaks tied to the heat index — and a way to show they actually happened.
Skipping acclimatization during the first hot week
A disproportionate share of serious heat illnesses happen in the first few days of hot weather or on a new hire's first week. Gradually increasing exposure over 7–14 days is one of the most protective and most overlooked controls.
Assuming indoor work is exempt
The proposed rule explicitly covers indoor work settings. Warehouses, commercial kitchens, laundries, and manufacturing floors regularly exceed the heat-index triggers and are squarely in scope.
Having a plan no one has seen
A written plan that lives in a binder no employee can locate, or that exists only in English when part of the crew speaks Spanish, will not hold up to an inspection or a serious incident.
No training records
If training happened but isn't documented — date, topics, attendees, language — OSHA treats it as if it didn't happen.
Frequently asked questions
- Is the OSHA heat rule final yet?
- No. As of 2026, the Heat Injury and Illness Prevention rule is a proposed federal standard moving through rulemaking. It is not yet enforceable as a heat-specific standard. However, OSHA already cites heat hazards under the General Duty Clause and is actively inspecting under a heat-focused National Emphasis Program, so employers should not wait for the final rule to prepare.
- Does the proposed rule apply to small businesses?
- Yes. The proposal does not include a small-employer carve-out. A small landscaping crew, restaurant kitchen, or warehouse with employees exposed to heat would be expected to maintain a written plan and follow the same heat-index triggers as a large employer, scaled appropriately to the size of the operation.
- What are the heat-index triggers in the proposed rule?
- The proposal uses two thresholds: an initial trigger around 80°F (27°C) heat index, which requires water, rest as needed, shaded break areas, and a written plan; and a high-heat trigger around 90°F (32°C) heat index, which adds mandatory paid rest breaks, a buddy system, hazard alerts, and acclimatization.
- Does the rule apply to indoor workplaces?
- Yes. The proposed rule explicitly covers indoor work settings such as warehouses, commercial kitchens, manufacturing plants, and laundries when the heat index reaches the triggers. Indoor heat exposure is a primary focus area of OSHA's current heat enforcement.
- What is acclimatization and who needs it?
- Acclimatization is a gradual increase in heat exposure — typically over 7 to 14 days — that lets the body adapt to working in heat. It is recommended for new hires, employees returning after 14 or more days away, and the entire crew during sudden heatwaves where temperatures jump significantly above recent norms.
- How much water does the proposed rule require?
- The proposal aligns with OSHA's longstanding guidance: cool drinking water made readily accessible at no cost, with enough supply to provide at least one quart per employee per hour during heat exposure.
- What should a written heat plan include?
- At minimum: the designated person responsible for the plan, the heat-index source you monitor, the specific actions taken at each trigger, the acclimatization schedule, training requirements, emergency response steps, and the languages the plan is available in. It should be accessible to employees, not buried in a back-office binder.
Author
WorkplaceReady Editorial Team
WorkplaceReady publishes practical, OSHA-aligned guidance on workplace heat safety, risk assessment, and emergency response — written for the people responsible for keeping workers safe.