How does sunscreen work, and what do SPF and star ratings mean?

The NHS says most people do not apply enough sunscreen.

It recommends that adults use around six to eight teaspoons of sunscreen, external if they are covering their entire body.

Sunscreen should be applied to all exposed skin, including the face, neck and ears – and head if you have thinning or no hair – ideally 30 minutes before you go out into the sun.

It should be reapplied every two hours, or sooner if you sweat a lot, have been in water, or after drying yourself with a towel.

This is the case even if the sunscreen says it is water resistant, or describes itself as long-lasting.

However, no sunscreen provides absolute protection from UV radiation.

So, you should wear trousers or skirts with a fabric that does not allow sunlight through, a top with long sleeves, a sun hat and sunglasses.

Spend time in the shade during the hottest part of the day.