What to look for when choosing sunscreen and how to apply it to get the maximum protection.

Sunscreen protects your skin from the damaging effects of UV radiation, and can help prevent skin cancer. Sunburn is a clear sign that your skin has been damaged, but you do not actually need to burn to sustain skin damage. Some exposure to UV radiation is beneficial, because it enables our skin to produce essential vitamin D. This is important for the function of bones, blood cells and our immune system. The number of new melanoma skin cancer cases diagnosed in the UK in a year has risen above 20,000 for the first time. The charity Cancer Research UK says too much exposure to UV - from sitting in the sun and sunbeds - is part of the cause, with an estimated nine in every 10 cases thought to be avoidable. The UV Index is a measure of UV radiation used around the world. It starts at zero and can rise above 10. According to Cancer Research UK, external, if the UV index is three or above, you should consider using sunscreen and covering up. Higher readings require more protection. Levels of UV radiation vary throughout the day, with the highest readings over a four-hour period when the sun is at its highest - usually from late morning to early afternoon.