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Cold stress calculator: work and warm-up schedule

Updated October 18, 20262 min tool
1

The conditions

Units
°C
km/h

From the forecast, at 10 m.

The work
Wind
Clothing
h
2

The schedule

Work at most 55 minutes, then warm up for 10

3 warm-up breaks in every four hours of work, and an extended break somewhere warm at the end of each four hours.

Wind chill

-42°C

Very high risk.

Exposed skin freezes

5 to 10 minutes

Sooner in winds over 50 km/h.

Longest work period

55 min

Warm-ups in 12 h

9

10 minutes each, somewhere warm.

Each four hours
53′
10′
53′
10′
53′
10′
53′
Warm break

Blue: work. Amber: a 10-minute warm-up. Green: the extended warm break at the end of each four hours.

Air °CNo noticeable wind8 km/h16 km/h24 km/h32 km/h
−26 to −28NormalNormal75′ · 255′ · 340′ · 4
−29 to −31Normal75′ · 255′ · 340′ · 430′ · 5
−32 to −3475′ · 255′ · 340′ · 430′ · 5Stop
−35 to −3755′ · 340′ · 430′ · 5StopStop
−38 to −3940′ · 430′ · 5StopStopStop
−40 to −4230′ · 5StopStopStopStop
−43 and colderStopStopStopStopStop

Each cell: the longest work period and the warm-up breaks in four hours of moderate to heavy work. Light work uses the row below. Above −26 °C, normal breaks.

Wind chill risk

Low

0 to -9 °C

Moderate

-10 to -27 °C

High

-28 to -39 °C

10–30 min

Very high

-40 to -47 °C

5–10 min

Severe

-48 to -54 °C

2–5 min

Extreme

-55 °C ↓

under 2 min

Controls for these conditions

  • At -7 °C wind chill or colder: a work and warm-up routine, and heated shelters (a tent, cabin or trailer) close by and used regularly.
  • At -12 °C wind chill or colder: workers under constant watch (a buddy system or supervisor), a pace that avoids heavy sweating, time for new workers to get used to the cold, the weight and bulk of clothing allowed for in the work, and no long periods sitting or standing still.
  • Measure and record the temperature (and wind) at least every four hours.
  • Gloves for light work below 4 °C, and for moderate work below -7 °C; insulate metal handles for fine work below -1 °C.
  • Wind-protective outer layers below -12 °C, and insulated clothing and footwear below -18 °C.
  • Screens, windbreaks or an enclosure that stop the wind move the schedule to the "no noticeable wind" column.
  • For lone or remote work, a buddy system or reliable two-way radio, and survival gear in vehicles.

The rules · Alberta

  • No cold-specific rule: cold is a hazard the employer assesses and controls under the OHS Code’s hazard assessment requirements (Part 2) and the general duty in the OHS Act (s.3).
  • Alberta’s “Working in winter” bulletin recommends a work and warm-up schedule, a buddy system, heated shelters and protection from the wind.
Working in winter (GS014)

A summary to plan with. The regulation and your employer's procedures govern.

Enter the temperature and the wind, and this calculator gives the wind chill, how fast exposed skin can freeze, and the work and warm-up schedule for the crew: the longest work period, the warm-up breaks in every four hours, and when non-emergency work stops.

How the schedule works

The work and warm-up schedule comes from the ACGIH cold stress guidance and was first set out by Saskatchewan. It assumes moderate to heavy work, dry clothing, 10-minute warm-up breaks somewhere warm, and an extended warm break at the end of every four hours. Breaks start at about −26 °C in a 16 km/h wind; the colder and windier it gets, the shorter the work periods and the more breaks, until non-emergency work stops.

  • For work with little physical movement, use the next colder row.
  • Where screens, windbreaks or an enclosure stop the wind, use the “no noticeable wind” column.
  • Riding in an open vehicle, or anything else that makes its own wind, needs more breaks.
  • Wet skin in the wind: take the air temperature 10 °C colder.
Know the signs, and act on them
Shivering, numbness and pale, waxy skin are the first signs. Confusion, slurred speech, clumsiness and shivering that stops are hypothermia: a medical emergency. Get the worker somewhere warm, remove wet clothing, warm the core gently, and call for help.

Frostbite and hypothermia first aid

  • Frostbite: warm the area gently (hands in armpits), move indoors, and never rub it or apply snow. Don't rewarm if it could freeze again.
  • Hypothermia: handle the person gently and keep them lying down, warm the chest, armpits and groin first, give warm sweet drinks only if they are alert, and start CPR if breathing stops.

Plan the first aid your site needs with the first aid requirements calculator, and our training covers working in the cold.

Sources: WorkSafe Saskatchewan, Working in Cold Conditions (the ACGIH work/warm-up schedule, checked against the ACGIH 2012 table); Environment and Climate Change Canada, Wind Chill Index and its wind chill calculator; CCOHS, Cold Environments; ESDC, Thermal stress in the work place; the OHS regulations of each jurisdiction (sections in the rules panel). Wind speeds between the chart's columns are taken at the next column up.

Frequently asked questions

At what temperature should outdoor work stop in Canada?
Under the ACGIH work and warm-up schedule that most Canadian jurisdictions use or point to, non-emergency work stops at about −43 °C with no noticeable wind, and at warmer temperatures as the wind rises: about −32 °C in a 32 km/h wind. Where the wind is stronger than the chart, work stops at a wind chill of −51 °C.
How often should workers take warm-up breaks in the cold?
Warm-up breaks start at about −26 °C in a 16 km/h wind. From there the schedule shortens the longest work period (75, 55, 40 and then 30 minutes) and adds 10-minute breaks somewhere warm, up to five in a four-hour period, with an extended warm break at the end of each four hours. For work with little physical movement, use the next colder row.
How fast can frostbite happen?
Environment and Climate Change Canada says exposed skin can freeze in 10 to 30 minutes at a wind chill of −28 to −39, 5 to 10 minutes at −40 to −47, 2 to 5 minutes at −48 to −54, and in under 2 minutes at −55 or colder, faster in winds over 50 km/h.
Is there a legal limit for working in the cold in Alberta?
No. Alberta’s OHS legislation doesn’t set a cold limit: cold is a hazard the employer must assess and control, and Alberta’s own guidance recommends a work and warm-up schedule, a buddy system and heated shelters. BC, Manitoba, New Brunswick, Nova Scotia, PEI and Newfoundland and Labrador write the ACGIH cold stress limits into their regulations.

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