When you’re cold, blood vessels in your skin, arms, and legs
constrict, decreasing the blood flow to your extremities. This
helps your critical organs stay warm, but you risk frostbite in
The wind accelerates heat loss. For example, when the air
temperature is -30°C,
•	 with 16 km/h wind (a flag will be fully extended) your
skin can freeze in about a minute
•	 with 48 km/h wind your skin can freeze in 30 seconds.
This means that your flesh freezes. Blood vessels are damaged
and the reduced blood flow can lead to gangrene. Frostbitten
skin looks waxy and feels numb. Once tissue becomes hard,
it’s a medical emergency.
•	 Get medical aid.
•	 Warm area with body heat—do not rub.
•	 Don’t thaw hands and feet unless medical aid is distant
and there’s no chance of refreezing. Body parts are better
thawed at a hospital.
This means your core temperature drops. Moderate symp-
•	 blue lips and fingers
slow breathing and heart rate
•	 disorientation and confusion
•	 poor coordination.
•	 heart slowdown to the point where pulse is irregular or
hard to find
•	 no shivering
•	 no detectable breathing
resembles death—assume casualty is alive.
•	 Hypothermia can kill—get medical aid immediately.
•	 Carefully remove casualty to shelter. (Sudden movement
can upset heart rhythm.)
•	 Keep casualty awake.
•	 Remove wet clothing and wrap casualty in warm covers.
•	 Apply direct body heat—rewarm neck, chest, abdomen,
and groin, but not extremities.
If conscious, give warm, sweet drinks.
Here’s how to control cold stress:
•	 Wear several layers of clothing rather than one thick layer
to capture air as an insulator.
•	 Wear synthetic fabrics next to the skin to “wick” away
If conditions require, wear a waterproof or windresistant
•	 Wear warm gloves.
•	 Wear hats and hoods. You may need a balaclava.
•	 Tight-fitting footwear restricts blood flow. You should be