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- Simply using sunscreen can not prevent skin cancer, but sunscreen can help to protect your skin from the sun damage that causes it.
- No sunscreen can completely shield you from UV rays.
- Sunscreen should not be used as a means of extending the time you spend in the sun, but only to help you avoid sunburn.
How do they work?
They work by absorbing or scattering the harmful ultraviolet (UV) radiation in sunshine, and so limit the amount of UV rays penetrating the skin.
Most of the sunscreens produced nowadays by the large, well-known manufacturers give almost equal ‘broad spectrum’ protection against both UVA and UVB radiation.
The higher the SPF (sun protection factor) number on a sunscreen, the more effective it is supposed to be at reducing the risk of sunburn. The protection factor indicates how many hours it will take for you to get the same amount of UV radiation as you would get in one hour without any protection. SPF ratings start at 2-4, which shows low protection that allows tanning. An SPF rating of 15 or more, gives high protection from sunburn, and allows little or no tanning if applied thickly according to manufacturer’s instructions. SPF ratings are standard the world over.
The amount of burning rays your skin will receive will vary according to the time of year, the time of day, your skin type and the carefulness with which you apply the sunscreen. Most people use about a third of what is recommended, so dividing the SPF by 3 may give you a more accurate measure of your protection.
There is no globally recognised UVA sun protection factor rating. In the UK manufacturers give a standardised Star Rating to their products, with more stars meaning more protection. Four or five star ratings give the most protection.
In Britain, there is no need to use sun screen during the winter. In the sunnier months, you should use it if you expect to be out for more than 20 minutes. Apply it about 20 minutes before you go out to allow it to dry and be absorbed by the skin. A second coating, applied 20 minutes later should protect you for the rest of the day. You should only need to re-apply it to areas you have rubbed down, for example after swimming, or after exercise or heavy work.
However, the risk relationship between sun exposure, the use of sun block, and skin type, is not yet fully understood.
Some safety concerns have been raised that the chemicals in sun-screens may cause skin cancer. The North of England Cancer Network’s view is that there is no evidence for this, that sun-screens are safe, and that their use is recommended. But the best sun protection you can have is to stay in the shade, and to cover up when in the sun.
