🥶 Cold, in degrees and minutes
A single temperature scale to compare three dangers: wind chill on exposed skin, cold water immersion, and the four clinical stages of hypothermia — along with the time you have left before it gets serious.
★ At -40°C with 60 km/h wind, the wind chill drops to about -64°C: exposed skin freezes in under 2 minutes.
★ The 1-10-1 rule (Dr. Giesbrecht) sums up cold water immersion: 1 minute to control cold shock, 10 minutes of useful movement, 1 hour before unconsciousness.
★ A victim of severe hypothermia may look dead (undetectable pulse, no vital signs) yet still be resuscitable: mountain medicine says they are 'not dead until warm and dead.'
★ Wool retains most of its insulation when wet, whereas cotton loses almost all of it — that's the core of the 'cotton kills' rule in cold environments.
★ The moment shivering stops in a person who is cold, it's a major red flag: their body has entered moderate hypothermia, it's not a sign of improvement.
Temperature : Wind chill feel, water temperature, or core temperature depending on the category — lower is better.
Sources (5)
- Environment Canada / NWS — Wind Chill Index, joint 2001 formula
- National Weather Service — Wind Chill Chart (time to frostbite by risk level)
- Revised Swiss System — Clinical staging of accidental hypothermia (ICAR MedCom)
- US Coast Guard — Cold Water Survival, incapacitation and survival time by water temperature
- Dr. Gordon Giesbrecht — 1-10-1 rule for cold water immersion