In May this year, consumer watchdog Which? tested four sunscreens labelled “once-a-day” and found that after six to eight hours, their average SPF decreased by 74 per cent, to as little as SPF 8. “I don’t think once-a-day sunscreens should exist, they’re ineffective,” says Dr Nicholas Lowe, consultant dermatologist and spokesperson for theBritish Association of Dermatologists. “Sweat, face-wiping, exercising, swimming, all mean it just won’t stay on. Put it on in the morning and reapply it at lunchtime.” The Which? research also tested 11 common sunscreens with an SPF of 30 and found own brand sunscreens from Asda, Lidl and Wilko all stood up to scrutiny.
The new rays
We know that sunlight damages the skin because of UVB, the rays that cause sunburn and can lead to skin cancer, and UVA rays, present even on cloudy days, which penetrate deep below the skin, causing premature ageing and are also linked to melanoma. A suncream’s SPF rating relates to protection from UVB, while its star rating – five being the highest – relates to UVA protection. However, UV light makes up only about seven per cent of the sun’s rays. About 50 per cent of it is made of infrared-A (IR-A) light. “IR-A appears to induce free radical formation and penetrate the skin, causing damage that can potentially lead to skin ageing. Traditional suncreams do not generally have IR-A protection,” says Dr Anjali Mahto, dermatologist and spokesperson for the British Skin Foundation.