Environmental hazards: heat, cold and altitude

11.1  Ultraviolet radiation

Around 40,000 people in the UK develop skin cancer each year, a figure which is rising by five to six per cent annually. Between 1989 and 1998, deaths from malignant melanoma rose by 35 per cent. This upward trend is believed to be due to the increased extent to which people with mainly white skin expose themselves to ultraviolet radiation (UVR), primarily sunlight, but probably also from sun beds and similar devices. Much exposure, is associated with foreign travel and summer holidays.

While the sun should be enjoyed, advice on sunbathing should clearly take account of the risks as well as the benefits and overexposure at times when ultraviolet intensity is high should be avoided.

11.1.1  Those most at risk include:

•   babies and children

   

•   those with pale skin which sunburns easily, fair or red hair, freckles or with over 50 normal moles or with a family history of malignant melanoma

   

•   dedicated sun worshippers

   

•   outdoor workers

For people with brown or black skin the risk of sun induced skin cancer is minimal, although skin photoageing still fairly readily occurs.

11.1.2  What to advise

The UK Skin Cancer Prevention Working Party has estimated that at least four out of every five skin cancers are preventable and issued the following statements:

1.  There is increasing evidence that excessive sun exposure, and particularly sunburn when aged under 15, is a major risk factor for skin cancer in later life. Protection of the skin of children and adolescents is therefore particularly important.

2.  Sun induced skin damage is cumulative.

3.  Sun exposure giving rise to sunburn and subsequent skin damage can take place even in the UK.

4.  Those who have an outdoor occupation and those with an outdoor recreation such as golf, gardening, skiing or sailing, are also at risk and should learn to protect their skin.

5.  A tan is a sign that already damaged skin is trying to protect itself from further damage.

6.  To minimise sun induced skin damage:

•   Avoid noonday sun (between 11.00am and 3pm).

   

•   Seek natural shade in the form of trees or other shelter.

   

•   Use clothing as a sunscreen including T-shirts, long-sleeved shirts and hats.

   

•   Use a broad spectrum sun screen with an SPF of 15 or higher to protect against UVB, and with UVA protection.

11.1.3  Sunbeds

Those who use sunbeds either before travel or as a regular exercise should be advised that they emit ultraviolet radiation which is likely to age the skin prematurely and increase the risk of skin cancers. Those under 16 years old, people who burn easily or tan poorly, those taking photosensitising drugs and those with a strong family history of skin cancer should be advised not to use them at all.

11.2  Heatstroke

A separate risk of overexposure to the sun, particularly overseas, is sunstroke or heatstroke, caused simply by overheating. People acclimatise to the heat. Taking it easy for the first few days of exposure is important and strenuous exercise should be avoided. Once acclimatised, water requirements increase rather than decrease and an adequate fluid intake (of non-alcoholic 'safe' liquids) is still of major importance to balance the loss of body fluid through perspiration. For those eating a normal diet, extra salt is not advised.

11.3  Cold

11.3.1  The major risks to people exposed to the cold are:

•   local cooling, primarily affecting the hands and feet which may freeze (frostbite) or remain cold but unfrozen for long periods (non-freezing cold injury or ìtrenchfootî which primarily affects the feet);

   

•   general body cooling leading to hypothermia.

Those at greatest risk are the ill prepared.

Frostbite can occur in anyone exposed to temperatures below freezing without adequate protection to the extremities, and non-freezing cold injury can occur where the feet are cold (and generally wet) for extended periods. Visitors to cold climates should be aware of the symptoms of hypothermia, which can include subtle mood changes, stumbling and apparent tiredness.

Prevention is by the provision of appropriate clothing including hat, gloves/mittens, suitable socks and boots. Loss of articles of clothing in an accident can be disastrous unless spares are carried. There is an abundance of excellent protective clothing available; fashion should not override safety. If there is the slightest risk that the individual may need to camp out, food rations and a sleeping bag should be carried.

Specialist advice should be sought as to the best equipment for a trip, including a survival bag.

Treatment of someone suffering from hypothermia entails preventing any further drop in body temperature. This should involve seeking shelter and insulating and protecting the victim. Metallised plastic sheeting (space blanket) is ineffective in field conditions and conventional plastic bags (which eliminate evaporative heat loss) are more effective and practical. Great care should be taken in evacuation and rapid rewarming should be avoided unless the individual is well and conscious. Frostbite should not be defrosted if there is a likelihood of re-freezing occurring as this will greatly exacerbate the problem.

11.4   Altitude

Cold is a factor generally experienced at altitude, and the risks and precautions that need to be taken follow those given above.

Altitude-induced illnesses include Acute Benign Mountain Sickness, the symptoms of which include headache, nausea, dizziness, loss of appetite, vomiting and insomnia, which can progress to Acute High Altitude Pulmonary and Cerebral Oedema, a life threatening disorder which most frequently occurs following a rapid ascent to high altitude.

Avoidance of these conditions is best achieved by maximising the opportunity to acclimatise and this should be built into the itinerary. The appearance of any symptoms of Acute Mountain Illness should prompt consideration of descent, or at least the decision to go no higher until they resolve. Continued symptoms should trigger a timely shift to a lower altitude.

Prophylaxis: for susceptible travellers, or when time for natural acclimatisation is limited, prophylactic acetazolamide has been effective in preventing altitude illness, but it has not been shown to protect against cerebral or pulmonary oedema. Paraesthesiae in the fingers and toes are common during the first two days of treatment; sulphonamide allergy, and impaired renal function are contraindications to its use.