Bushwalking in hot and humid weather interferes with the normal body cooling process of evaporation from the lungs and skin, and may lead to heat exhaustion. If this state is not recognized and treated promptly it may progress to the more serious and potentially fatal condition of heat stroke in which the body temperature rises due to failure of the heat regulating centre in the brain
- When walking in hot weather, drink plenty of water
- Avoid activity in the hottest part of the day by planning to rise early, take a midday siesta or reduce the distance to be covered during the day
- Plan mid summer trips near watercourses and do not overextend the party
- Wear a hat and avoid sunburn
- Drink plenty of water before commencing the day's walking
Early symptoms are thirst, muscle cramps and weakness, headache, feeling hot, faint, giddy and nauseous. The victim develops rapid pulse and breathing accompanied by excessive sweating. As the dehydration becomes more severe, the skin becomes hot and dry, with headache, nausea, vomiting and mental disturbance common prior to collapse and unconsciousness.
- Assist the victim to rest in a cool and shaded area
- Remove unnecessary clothing, sponge with cool water and fan the victim
- Give frequent cool drinks
- Gently stretch any cramped muscles
- In extreme cases immerse the victim in water or if this is not possible, cover with a wet sheet or tent
- Where Heat Exhaustion has developed into Heat Stroke, the condition is potentially fatal, and the first aider must act urgently to call emergency services
The gradual onset of the effect of exposure to extreme cold may be overlooked in the early stages. When the body loses heat faster than it can create it and the core temperature is lowered, the condition is known as hypothermia. It is responsible for several deaths each year in Australia.
- Carry and wear suitable clothing to ensure you always have adequate protection from the cold particularly when combined with wet and windy conditions (ref clothing)
- Ensure a regular intake of food (high calorie) and drink. Do not drink alcohol which accelerates heat loss.
- On overnight walks be self sufficient and do not rely on reaching mountain huts for shelter.
- Avoid physical exhaustion by walking within your party's capabilities.
- Take particular care when walking with more susceptible people, such as young children, slightly built, weak or less fit individuals.
- Take into account that long stops or immobilisation due to injury increase susceptibility.
- Be aware of the early signs of hypothermia.
The early warning signs of tiredness, shivering and lagging behind and stumbling are a signal to assess the situation and take preventative action with respect to clothing, food, drink and rest. Difficulty unwrapping a sweet such as a barley sugar is a simple test for loss of usual co-ordination.
As body temperature continues to fall, mental and physical performance declines rapidly, often unbeknown to the victim. The danger signs requiring prompt action to prevent a potential fatality are uncontrollable shivering or a cessation of shivering, pain in the limbs, unusual or irrational behaviour, poor judgement, apathy, lack of co-ordination, exhaustion, confusion, hallucinations, slurred speech and blurred vision. The victim will feel cold to touch and is usually pale. Untreated they will collapse, pass into a stupor, unconsciousness and death.
The basic principles of first aid and resuscitation apply, in addition to the following measures to prevent further body cooling.
- STOP IMMEDIATELY
- Protect the victim from the cold environment by finding a nearby or improvised shelter from the wind and the wet, and insulating the body from the ground.
- Put on extra layers of clothing and a sleeping bag if available, remembering to cover the head.
- Enclose in a waterproof layer, such as a large plastic garbage bag pack liner, bivvy bag, ground sheet or safety blanket.
- Huddle together to warm the victim by body heat from other party members.
- DO NOT attempt to restore body heat by massage, warming beside a fire or hot water bottles. External heating that is too rapid may actually cause the core temperature of the victim to drop.
- Give warm sweet drinks and easily digestible food if conscious.DO NOT give victim alcohol, cigarettes, coffee, tea or hot drinks.
- Ensure other party members are adequately clothed and not in similar danger.