Heat kills construction workers every summer, and almost every death is preventable with three things: water, rest, and shade. There is no single federal heat rule in force yet, but that does not mean you are off the hook. OSHA cites employers for heat hazards under the General Duty Clause, Section 5(a)(1) of the Occupational Safety and Health Act of 1970, which requires a workplace "free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees." Five states have gone further and written their own heat standards: OSHA names Washington, Minnesota, California, Oregon and Colorado. Know the warning signs, and know your state's rules.
Water, rest, shade
The whole prevention plan comes down to three habits on a hot day:
- Water: cool water within reach, and drink small amounts often, before you feel thirsty.
- Rest: scheduled breaks in the shade, more often as it gets hotter. Pushing through is how people collapse.
- Shade: somewhere out of the sun to take those breaks and cool down.
And one more that saves lives: ease new workers in. Many heat deaths happen in a worker's first days on the job, before their body has adjusted to the heat. New and returning workers should build up over about a week, not go full tilt on day one.
Know the two stages
- Heat exhaustion: heavy sweating, weakness, dizziness, nausea, headache. Stop, get into shade, drink water, cool down. Take it seriously, because it is the warning before the dangerous stage.
- Heat stroke is a 911 emergency. Confusion, slurred speech, collapse, and skin that is hot and either soaking or oddly dry. Call 911 immediately and start cooling the person with water and shade while you wait. Heat stroke kills fast, and minutes matter.
The law
There is no final federal heat standard yet, but "no specific rule" does not mean "no enforcement", and it is worth knowing exactly where the rule has got to rather than taking anyone's word that it is still coming.
Where the federal rule actually stands. OSHA published a Notice of Proposed Rulemaking for Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings in the Federal Register on 30 August 2024. The informal public hearing on it concluded on 2 July 2025, and the post-hearing comment period closed on 30 October 2025. As at the date this guide was last checked, no final rule had issued. Those dates are given deliberately: if you find that the comment period is no longer the last thing that happened, this page is behind and you should go to osha.gov/heat-exposure/rulemaking.
What enforces it in the meantime. Two things. The General Duty Clause, Section 5(a)(1) of the Occupational Safety and Health Act of 1970, which requires a workplace "free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees", and a National Emphasis Program on outdoor and indoor heat-related hazards, OSHA Directive CPL 03-00-024. An emphasis program means inspections targeted at this hazard on purpose, not only in response to a complaint.
The states that have their own standards. OSHA names five: Washington, Minnesota, California, Oregon and Colorado. Several trigger around 80 degrees and require water, shade, rest breaks and an acclimatization plan, but the trigger temperature and what it requires differ, so the state rule is the one to read. Whether your state has one, and exactly what it requires, is in Working in Your State.
The move
On a hot day: water within arm's reach, shade set up, breaks on the clock, and eyes on your newest workers hardest. It costs almost nothing and it is the difference between a tough day and a fatality.
Common questions
What are the warning signs of heat stroke?
Heat stroke shows up as confusion, slurred speech, collapse, and skin that is hot and either soaking wet or oddly dry, and it is a 911 emergency. Call 911 immediately and start cooling the person with water and shade while you wait. Heat stroke kills fast and minutes matter, so do not wait to see if they improve on their own.
Is there a federal OSHA heat standard?
Not a final one yet. The proposed rule, Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings, was published in the Federal Register on 30 August 2024; the public hearing concluded on 2 July 2025 and the post-hearing comment period closed on 30 October 2025, with no final rule issued as at the date this page was last checked. In the meantime OSHA enforces heat as a serious hazard under the General Duty Clause and runs a national emphasis program on it, so "no specific rule" does not mean "no enforcement." Verify the current status at osha.gov.
What temperature do heat illness rules kick in at?
Several states with their own heat standards trigger around 80 degrees, but the exact temperature and requirements vary by state. Federal OSHA has no numeric trigger yet. Because this is one of the most state-specific parts of site safety, check Working in Your State for the rule that actually applies to your job.
How do you prevent heat illness on a construction site?
Water within reach, scheduled rest breaks in the shade, and a shaded place to cool down, plus easing new workers in over about a week. Drink small amounts often before you feel thirsty, take breaks more often as it gets hotter, and watch your newest workers hardest. It costs almost nothing and prevents nearly every heat death.
Why are a worker's first days on the job the most dangerous in heat?
Because the body needs time to adjust to working in heat, and many heat deaths happen in a worker's first few days before that adjustment has happened. New and returning workers should build up their workload over about a week rather than go full tilt on day one. This gradual build-up is called acclimatization.
The honest bit
- The federal heat standard is still being written, and state rules vary and change. Confirm your state's requirements in Working in Your State.
- Heat stroke is a medical emergency. When in doubt, call 911 and start cooling the person.
- This is general guidance, not training or medical advice.
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Keep reading
Templates you might need
Sources
- OSHA Heat - Overview: Working in Outdoor and Indoor Heat Environments · That heat is enforced under the General Duty Clause rather than a specific construction standard, and the water, rest and shade guidance
- Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings Rulemaking | Occupational Safety and Health Administration · The federal heat rule's actual position: the Notice of Proposed Rulemaking published in the Federal Register on 30 August 2024, the informal public hearing concluded 2 July 2025, and the post-hearing comment period closed 30 October 2025
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