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What is hypothermia?
Hypothermia is a physical condition that occurs when the body’s core temperature falls below a normal 98.6° F (37° C) to 95° F (35° C) or cooler. Think of hypothermia as the opposite of heat stroke. Cold water dangerously accelerates the onset and progression of hypothermia since body heat can be lost 25 times faster in cold water than in cold air. Hypothermia affects the body’s core – the brain, heart, lungs, and other vital organs. Even a mild case of hypothermia diminishes a victim’s physical and mental abilities, thus increasing the risk of accidents. Severe hypothermia may result in unconsciousness and possibly death. About 600 people in the U.S. die of hypothermia each year.
Who is at risk for developing hypothermia?
Elderly people, homeless people, and those under the influence of alcohol or drugs are particularly vulnerable to hypothermia. Children and people with certain health disorders are also susceptible. So are outdoor enthusiasts who spend time boating, fishing swimming, hiking, or skiing. How quickly a person becomes hypothermic depends on a variety of factors, including personality, behavior, physical condition, clothing, and environmental factors. Everyone reacts differently to the cold, even under the same conditions. Generally, children lose body heat more quickly than adults and thin people lose body heat faster than overweight people. People dying of hypothermia in the U.S. are likely to be older than 60, male, unmarried, and living in Alaska, Montana, or Wyoming.
|IF THE WATER TEMPERATURE (F) IS:||EXHAUSTION OR UNCONSCIOUSNESS||EXPECTED TIME OF SURVIVAL IS:|
|32.5||Under 15 Minutes||Under 15 – 45 Minutes|
|32.5 – 40.0||15 – 30 Minutes||30 – 90 Minutes|
|40.0 – 50.0||30 – 60 Minutes||1 – 3 Hours|
|50.0 – 60.0||1 -2 Hours||1 – 6 Hours|
|60.0 – 70.0||2 – 7 Hours||2 – 40 Hours|
|70.0 – 80.0||3 – 12 Hours||3 Hours – Indefinitely|
The use of an Immersion Suit or other buoyant thermal protective device will greatly enhance survival time.
Chart is for general reference only.
- Body thermal conductivity in water is 26 times faster than when exposed to air. If you have a life raft, board as soon as possible.
- 50 degree water equals 15 minutes before incapacity and/or unconsciousness with life jacket on.
- 50 degree water equals 9 minutes before incapacity and/or unconsciousness without a life jacket.