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Toolbox talk · 10 min · Heat & Cold Stress

Cold Stress and Hypothermia

Hazards: Hypothermia, including at temperatures above 40 degrees when wet · Frostbite of hands, feet, nose and ears · Trench foot from prolonged wet and cold · Slips on ice and reduced dexterity from cold hands

Why it matters

Cold injuries start warmer than the crew expects, and they start with wet. OSHA says trench foot can happen at 60 degrees Fahrenheit when feet stay wet, because wet feet lose heat 25 times faster than dry feet, and that hypothermia can occur above 40 degrees in someone chilled by rain, sweat or immersion. Hypothermia also takes your judgment early - which is why the person who says he is fine is often the one in trouble.

Key points

  • Plan on wind chill, not the thermometer. At 0 degrees with 15 mph of wind, exposed skin feels minus 19 and can freeze in 30 minutes. Check it before the shift, not after.
  • Wet is the real hazard. Trench foot at 60 degrees, chilblains just above freezing, hypothermia above 40 - all of them need moisture, and sweat counts as moisture.
  • Three loose layers, and no cotton next to the skin. Wool, silk or synthetic inside; wool or fleece to insulate; wind and rain outside. Cotton stops insulating the moment it gets wet.
  • Shivering that stops is an emergency. Uncontrollable shivering is mild hypothermia. Fumbling hands, confusion or slurred speech mean it has gone further - call 911.
  • Never rub or rewarm frostbite on site. Rubbing damages tissue, and an area that thaws and refreezes is worse off. Wrap it loosely in dry cloth and get medical help.
  • Warm up on a schedule, in a warm dry place. OSHA asks for frequent short breaks, heavy work in the warmest part of the day, and radiant heaters or wind shielding where the work allows.
  • Work in pairs and watch each other. The buddy sees the fumbling before you feel it - especially for anyone new to cold work or back after time away.

Do / Don't

Do

  • Keep dry spare socks, gloves and a hat in the truck, and change the moment you are wet.
  • Take warm sweetened drinks and high-carb snacks on the warm-up break.
  • Cover your head - a hat keeps the whole body warmer.
  • Say something the first time your fingers stop working properly.

Don't

  • Grab cold metal or wet surfaces with bare skin.
  • Wear tight boots or layers - they cut circulation to fingers and toes.
  • Drink alcohol to warm up, on or before shift.
  • Push a soaked worker through the last hour "to get it done."

Quick site check

  • What is today's wind chill, and where on this site is the wind worst?
  • Where is the warm dry break area, and is it actually heated right now?
  • Who is wet - boots, gloves, sleeves - and do we have dry replacements on hand?
  • Who is new to cold work or back from time off, and who is paired with them?
Discussion — ask the crew
  1. What is the wind chill right now on this side of the building, and how long is anyone exposed to it at a stretch?
  2. Where do we warm up today, and how long does it take to get there from the work?
  3. Who is soaked already - boots, gloves, sleeves - and do we have dry replacements on site?
  4. Who started this week or came back after time off? What are we changing for them today?
  5. If someone here started fumbling and slurring their words, what would we do in the next five minutes?
Refs: OSHA - Winter Weather: Cold Stress (types of cold stress, prevention, first aid, wind chill) · OSHA - Cold Stress Safety and Health Guide (Emergency Preparedness Guide) · National Weather Service - Understanding Wind Chill (formula, limits, and frostbite versus the freezing point) · National Weather Service - Cold products renamed effective October 1, 2024 (Cold Weather Advisory, Extreme Cold Watch and Warning)Sign-in sheet included in the printed version

Frequently asked questions

No. OSHA has no standard covering work in cold environments. Cold stress falls under Section 5(a)(1) of the OSH Act, the General Duty Clause, which requires employers to protect workers from recognized hazards likely to cause death or serious physical harm - and OSHA names cold stress as one.

Not very. OSHA says trench foot can occur at temperatures as high as 60 degrees Fahrenheit if the feet are constantly wet, because wet feet lose heat 25 times faster than dry feet. Redness, numbness, tingling, swelling and blisters are the early signs.

How fast exposed skin loses heat once wind is added. At 0 degrees with a 15 mph wind the wind chill is minus 19, and the National Weather Service says exposed skin can freeze in 30 minutes at that value. The index only applies at air temperatures of 50 degrees or below with winds above 3 mph.

Shivering is the body generating heat, and OSHA calls uncontrollable shivering an important mild symptom of hypothermia that should not be ignored. When shivering stops and the worker becomes clumsy, confused or slurred, the body has moved from mild to moderate or severe hypothermia. Call 911.

Neither. OSHA says do not rub or massage the area, because rubbing damages skin and tissue, and do not try to rewarm it before getting medical help - no heating pads, no warm water. If a frostbitten area is rewarmed and refreezes, more tissue is lost. Cover it loosely with dry cloth and protect it.

As of October 1, 2024 a Wind Chill Advisory is now a Cold Weather Advisory, a Wind Chill Warning is an Extreme Cold Warning, and a Wind Chill Watch is an Extreme Cold Watch. Cold is dangerous with or without wind, which is the point of the new names. Thresholds are set locally by each NWS office.

Sources & references

Content checked against these sources — last reviewed August 28, 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