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The active ingredients in sunscreens (called UV filters) are classified as either organic or inorganic.  Organic chemicals work by absorbing UV radiation, whereas inorganic chemicals both absorb and scatter the incident UV radiation. Many modern sunscreens contain a mixture of both organic and inorganic UV filters to provide broad spectrum protection against both UVA and UVB radiation.

The Sun Protection Factor (SPF) is a system used globally
to determine how much protection a sunscreen gives when applied to the skin at a thickness of 2mg/cm2 . The test measures how much protection against UV radiation the sunscreen provides, e.g. a product providing SPF30 will result in a skin exposure of just one-thirtieth that received by unprotected skin for the same time in the sun.

Sunscreens, in order to be protective, have to be applied liberally to be effective. This includes using it to all exposed areas and regularly reapplying sunscreen every 2 hours. This is especially after being in the water.

  • Choose broad spectrum SPF 30+ water resistant sunscreen.
  • Be aware that the price of sunscreen does not always match the quality.
  • Try a toddler sunscreen if you have sensitive skin. 
  • Apply sunscreen 20 minutes before you go outside.
  • Use a generous amount of sunscreen. Ideally, the average-sized adult should apply at least a teaspoon of sunscreen to each arm, leg, front of body and back of body and at least ½ a teaspoon to the face (including the ears and neck). That is, 35 ml of sunscreen for one full body application.
  • Many people find this quantity just too much, so one trick is to reapply once you are in the sun.  Think of applying sunscreen like painting a wall with a textured surface, when two coats is almost always required for satisfactory coverage.  In the same way two "coats of sunscreen" may be required for adequate protection.
  • No matter what the sunscreen instructions say, it is wise to reapply sunscreen every two hours when you are outdoors. Sunscreen can be easily wiped or perspired off and you need to keep putting sunscreen on to get the best protection.
  • A British Skin survey has revealed that over a third of British men and women are unsure of what an SPF is. People are also confused about the difference between UVA and UVB rays, with three-quarters of those questioned attributing UVA rays to burning and 77% UVB rays to ageing.

Click here to view the common myths about sunscreen and sunbathing

Click here for further information about sun protection