How much do I need?

At least six full teaspoons for an average adult. Anything less reduces protection.

How do you apply it?

Put it on 15 to 30 minutes before you go out in the sun, then 15 to 30 minutes afterwards – and every two hours after that. If you get sweaty or swim you need to reapply it even if it is water repellent. Don't rub it in too much – it should still look a bit white on your skin. Don't re-use last year's bottles – sunscreens can get damaged by heat and bacteria.

What SPF do I need?

Dermatologists recommend SPF 30. Children under six months should not be out in direct sun, but they need an SPF of 50. Sunscreen will also protect you from UV-A rays, which are also linked to skin cancer. Their protection is measured relative to the UVB protection given by a sunscreen and shown in stars – five gives 90% of the UVB protection.

Are clothes better protection?

Yes, if they are tightly woven and not light-coloured.