The main risks posed by a heatwave are:
For more information on heat exhaustion and heatstroke, see External Links.
A heatwave can affect anyone, but the most vulnerable people are:
Heat exhaustion occurs when the temperature of the inside of the body, which is known as the core temperature, rises to between 37-40°C (98.6-104°F). Heat exhaustion can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. Those most prone to heat exhaustion are elderly people, those with high blood pressure, and those working or exercising in a hot environment.
At that temperature, levels of water and salt in the body begin to drop leading to a range of symptoms such as nausea, feeling faint and heavy sweating.
Left untreated heat exhaustion can then progress to heatstroke.
The symptoms of heat exhaustion can develop rapidly. Symptoms include:
Heat stroke is the most serious heat-related illness. It occurs when the body becomes unable to control its temperature: the body's temperature rises rapidly above 40C (104F), the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes and many of the important functions of the body will begin to stop working.
Heat stroke can cause death or permanent disability if emergency treatment is not provided.
Heatstroke is a medical emergency. Left untreated heatstroke can cause multiple organ failure, brain damage and death.
The symptoms of classic heatstroke can develop over the course of several days if you are spending prolonged time in a hot environment. While the symptoms of exertional heatstroke can develop rapidly, usually after a long period of physical activity.
Symptoms of heatstroke may vary but include:
The extreme heat associated with heatstroke also affects the nervous system which in turn can cause additional symptoms such as:
Heatstroke is a medical emergency. If you are concerned that you or somebody you know may be experiencing the symptoms of heatstroke you should immediately dial 999 and ask for an ambulance.
The following advice applies to everybody when it comes to keeping cool and comfortable and reducing health risks. If you know or care for someone in one of the vulnerable categories above, you can also help them to follow this advice:
If someone feels unwell, get them somewhere cool to rest. Give them plenty of fluids to drink. Cool the person as rapidly as possible, using whatever methods you can. For example, immerse the victim in a tub of cool water; place the person in a cool shower; spray the victim with cool water from a garden hose; sponge the person with cool water; or if the humidity is low, wrap the victim in a cool, wet sheet and fan him or her vigorously.
If symptoms such as breathlessness, chest pain, confusion, weakness, dizziness or cramps get worse or don't go away, seek medical help.
Heat exhaustion and heatstroke both require urgent treatment.
|What to do||
Whilst you wait for the ambulance:
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Check the weather forecast and any high temperature health warnings at the Met Office
Contact NHS Direct on 0845 4647 or NHS Direct for advice about heat exhaustion and heatstroke.
You can get advice on protecting your skin during hot weather from the Cancer Research UK SunSmart site campaign website