• Occurs when the body’s core temperature falls below 35°C
• Air temperature of no great severity can produce it
• It’s onset can be so gradual that no one, including the victim, may notice it until too late
• Can occur at room temperature if an individual is wet, inadequately clothed, drunk, chronically ill or very old
• May affect the heart, lungs and other major abdominal organs as well as the skin and soft tissues chilblains or frostbite

Normal temperature is 37°C (98.6°F)

        Heat is produced by

• Breaking down of food during digestion (Metabolism)
• Muscular energy (75% converted to heat)
• Shivering

        Heat loss occurs by

• Direct contact with a colder object (Conduction)
• Movement of air or water near to the skin (Convection)
• Infrared energy emissions (Radiation) which cause approx. 65% of normal heat loss largely from the head and neck area
• Evaporation of sweat
• Breathing

• Inadequate clothing and insulating from the cold, particularly if wet
• High wind chill factor
• Immersion in cold water (21°C or less) for longer than 15 – 20 mins
• Leanness (the only advantage of obesity)
• Fatigue – being tired or exhausted
• Smoking
• Poor nutrition
• Age (very young or old)
• Poor circulation (arterial disease, tight clothing or shoes)

• Remove cold, wet clothing
• Protect from wind and rain
• Rewarm    (a) using blankets, sleeping bags, body contact
                   (b) slowly using a bath (40° – 42°C for the body trunk) but excluding arms and legs
• Handle gently (vigorous activity may cause cardiac arrest in extreme cases
• Give warm, sweet drinks and provide warm humidified air
• Continue CPR when needed until warming has occurred

Physical performance decreases if the body core temperature drops as little as 1°C, and shivering,may occur.

Shivering interferes with coordination and performance of fine movements and also depletes muscle stores of glycogen
(a storage form of energy) leading to early fatigue and hypoglycaemia (low  blood sugar)

•  Wear suitable clothing (this will often include a hat and gloves)
•  Warm up prior to exercise
•  Replace fluid loss – warm, sweet fluids (e.g. 2 ˝ % glucose solution)
•  Warm down and rug up following exercise