I work in catering and often get burned on the hand. Most of these are relatively minor, but painful. The National Health Service advice is to hold the burn under a running tap of cool water for 20 minutes and not to cover it in anything greasy. As burning is caused by a transfer of energy from one substance to another, even a hot oil burn doesn’t need that long to cool down. What is the basis for these measures?
• The length of time cool water has to be applied to a burn depends on the severity of the burn and how soon the water is applied. If a splash of hot water on the skin is put under a cold tap within seconds its heat will barely have penetrated. It may only need half a minute under the water before it is entirely neutralised.
But if a large quantity of boiling jam spills down your leg, it will take time to remove it. The heat will have penetrated some way into your leg before you begin to cool the skin, and will continue to go deeper into your tissues while you cool the surface layers.
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For minimum damage, cool water must be applied for the 20 minutes cited to ensure that it has reached all the heat.
Jane Lilley
Dorking, Surrey, UK
• Although it cannot be observed, thermal damage beneath the skin can continue once the source of the burn is removed and the burn feels cool.
For this reason it is better to apply cool water for longer rather than very cold water for a short time. If water is too cold it can lead to reduced sensitivity, making you believe the burn is no longer hot. It can also reduce blood flow, by constricting blood vessels, which slows down damage repair and can even trigger frostbite. Ice can also do this and shouldn’t be put on burns.
Vittoria Dessi
London, UK
• A 2008 study by of Queensland in Australia on the treatment of burns with cool water found recommendations ranging from 5 minutes to 3 hours. Testing on pigs showed treating burns with 20 minutes of cool water resulted in less damage after nine days compared with 5 or 10 minutes, and longer durations offered no additional benefit.
Interestingly, the study also says that while immediate treatment is best, a delay of 1 to 3 hours is acceptable. This suggests there may be more to the mechanism than simply removing residual heat, such as minimising inflammation.
Anthony Roberts
Rushden, Northamptonshire, UK
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