14 March 2012

The human body and cold water

The human body and cold water: some interesting comparative temperatures




Core temperature of the human body.

35°C If your core temp. drops below this, you have entered the deadly realm of hypothermia.
30°C (early 30s)  Temperature of the water in a "hot swim" e.g. in Lake Malawi.
27°C The indoor pool at your gym.
22°C Water off Muizenberg beach in summer.
18° English Channel, summer
15°C A cold shower.
11°C Swimming to Robben Island (on a bad day).
5°C Water temperature when the Titanic sank. Most of the deaths were due to hypothermia within an hour of immersion in the sea.
0°C Fresh water freezes. The human body can't withstand water temperatures below this for much longer than about 15 minutes, at most, before unconsciousness or exhaustion. Death occurs in under 15 to 45 minutes.
-1.7°C Water at the North Pole. The body loses heat in cold water much faster than in cold air (remember the end of Titanic, when Kate Winslett survives by reclining on a piece of flotsam, while Leonardo di Caprio stays in the water and cops it?), and a moving body loses heat much faster than a stationary one. Exercise pumps blood to your extremities where the water rapidly cools it.
-1.8°C  Salt water freezes

Coldest sea water ever measured, in a stream under a glacier in the Antarctic in 2010.

Compiled with assistance from Lewis Gordon Pugh

(Olivia Rose-Innes, Health24, updated January 2012)


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