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Toolbox talk · 10 min · Heat & Cold Stress

Heat Stress

Hazards: Heat stroke · Heat exhaustion · Dehydration · Heat cramps and rash · Reduced alertness leading to other incidents

Why it matters

OSHA states plainly that outdoor workers have died of heat stroke when the day's maximum heat index was only 86 °F. Not 105. Eighty-six. Heat does not have to feel extreme to kill someone who is unacclimatized, dehydrated, or working hard in the sun. There is no final federal heat standard yet, but OSHA inspects heat under the General Duty Clause and revised its heat National Emphasis Program on April 10, 2026, targeting 55 high-risk industries.

Key points

  • Water, rest, shade. That is OSHA's whole message, and it is prevention and treatment at the same time. Drink before you are thirsty; thirst already means you are behind.
  • New guys and returning guys are the ones who go down. Assume a worker is unacclimatized if they have been on the job less than one to two weeks — including after vacation or sick leave. Shorter shifts, more breaks, someone watching them.
  • Know the two numbers. In OSHA's proposed rule, a heat index of 80 °F starts water, break areas and acclimatization; 90 °F adds a 15-minute paid break at least every two hours and watching each other for symptoms.
  • Full sun adds up to 15 °F. The forecast heat index is a shade number. Add the sun, add the PPE, add the asphalt radiating back at you.
  • Heat exhaustion: get them cool, get them fluids. Heavy sweating, weakness, headache, nausea, dizziness, fast weak pulse. Stop work, cool place, water, do not leave them alone.
  • Heat stroke: call 911 first. Confusion, slurred speech, staggering, hot skin, sometimes no sweat, possible collapse or seizure. Call, then cool aggressively — ice, water, shade, remove gear. Minutes matter.

Do / Don't

Do

  • Drink about a cup of water every 15 to 20 minutes.
  • Take breaks in real shade or air conditioning.
  • Tell the foreman early when you feel off.

Don't

  • Wait until you are thirsty, dizzy, or cramping.
  • Use energy drinks or alcohol as hydration.
  • Send someone home alone who "just got overheated."

Quick site check

  • Water on site, cool, and enough for the whole shift — check the coolers now.
  • Break area with shade or AC, close enough to actually use.
  • Who is unacclimatized today, and who is watching them?
Discussion — ask the crew
  1. Who on this crew is new, back from vacation, or coming off light duty? What are we doing differently for them this week?
  2. Where is the closest shade or air conditioned break area to where we are working today — and how long does it take to get there?
  3. How much water is on this job right now, and does it get us through the afternoon?
  4. If somebody here got confused and stopped sweating, who calls 911 and what do we do while we wait?
Refs: OSHA — Heat: Overview, Working in Outdoor and Indoor Heat Environments (water, rest, shade; acclimatization) · OSHA — Heat Hazard Recognition (WBGT vs heat index; deaths at a heat index of 86 °F) · OSHA — Heat Injury and Illness Prevention proposed rule, regulatory text (initial heat trigger 80 °F, high heat trigger 90 °F) · OSHA — National Emphasis Program, Outdoor and Indoor Heat-Related Hazards (revised April 10, 2026)Sign-in sheet included in the printed version

Frequently asked questions

Not a final federal one. OSHA published a proposed heat rule and is reviewing the hearing record; in the meantime heat hazards are cited under the General Duty Clause, Section 5(a)(1) of the OSH Act, and OSHA runs a National Emphasis Program on heat that was revised on April 10, 2026.

A heat index of 90 °F is the proposed high heat trigger: a minimum 15-minute paid rest break at least every two hours, plus observation for signs and symptoms. The 80 °F initial trigger covers water, break areas and acclimatization.

OSHA says to assume workers are unacclimatized if they have been doing the job for less than one to two weeks. New and returning workers should build up gradually, take more breaks and be watched closely.

Heat exhaustion is heavy sweating, weakness, nausea, headache, a fast weak pulse — move the worker to a cool place, give water, cool them down. Heat stroke is confusion, slurred speech, hot skin, sometimes no sweating, and possible collapse: call 911 immediately, cool aggressively and stay with them. Heat stroke is a medical emergency.

Sources & references

Content checked against these sources — last reviewed August 27, 2026.

Results are estimates for planning purposes and do not replace a competent person's evaluation or an engineer's design. Follow the OSHA standards that apply to your work and your employer's written program.

By — Editorial team of SteelToeTools.com (published by LSEA SAS) Updated