Sunscreen: this summer’s biggest questions

Was Mark Zuckerberg’s ghostly facial application over the top? Can you avoid a face mask tan? Luke Mintz finds answers

Mark Zuckerberg was pictured gliding the waves on a $12,000 (£9,400) electric surfboard this week, but the only thing people wanted to know was: why did his face look so ghostly white? The 36-year-old Facebook founder appeared to have lathered himself in a comically thick layer of sunscreen to fend off the intense Hawaii rays. He was compared to the Joker, a mime artist, and Mrs Doubtfire.

Have we stumbled upon yet another secret Silicon Valley “life hack”, or was Zuckerberg simply taking his anti-skin cancer precautions too far? We asked the experts for the latest wisdom.

Should we all be doing a ‘Zuckerberg’ in hot weather?

The thicker your sunscreen, the better your protection; and most sunbathers do not apply anywhere near enough, says Dr Emma Wedgeworth, a consultant dermatologist and spokesman for the British Skin Foundation.

“If you buy Sun Protection Factor (SPF) 50 and you want that level of protection, then you have to apply the dose used in laboratory conditions to test that product – that’s about 2mg per centimetre squared, and equates to about a 30ml shot glass per application. People are using so much less than that, and that often means you only end up getting half of the protection,” she says.

So it could be that Zuckerberg was just following dermatologist’s orders with his lashings of cream, although Dr Wedgeworth thinks he was wearing zinc oxide, a physical sunscreen (rather than a chemical one) which sits atop the skin. “You can still have a decent level of protection and not look that white – but you do need to apply a significant amount of product.”

Have you missed a bit?

In terms of how we should be applying our sun protection, Dr Ross Perry, medical director of Cosmedicsuk, recommends “regular and bountiful application”: put it on 15 minutes before going outside, he says, and then use common sense regarding top-ups.

Around 10 per cent of malignant skin cancers begin on the eyelids

If you’re on a beach and exposed to sunlight all day, then “every couple of hours is sensible”, but if you’re just popping out to the shops then once should be enough.

It is important to cover any area of the skin exposed to the sun, including hands, feet and around your eyes. In 2017, scientists at the University of Liverpool found that three quarters of sunbathers are failing to apply any sunscreen to the area between the inner corner of the eye and the bridge of the nose, while one in seven left their eyelids unprotected. Around 10 per cent of malignant skin cancers begin on the eyelids. Take particular

care when using a transparent product, says Dr Wedgeworth: while they are “cosmetically elegant”, it is harder to see which areas of your skin are covered.

Is sunscreen really safe?

In a small study last year, researchers from the US Food and Drug Administration found that some substances in sunscreen can be absorbed into the blood. The chemical oxybenzone, for example, reached plasma concentrations of up to 209.6ng/ml – far exceeding the safe limit.

But the study involved massive doses of sunscreen, equivalent to applying it across three quarters of your body, every two hours for two weeks. And, while animal studies have shown some evidence of hormone disruption, no study has shown a particular threat to humans.

“The human data has been out for a long time and hasn’t shown any major issues,” says Dr Wedgeworth. “I wouldn’t want people to think that sun protection causes any damage to your body – what we do know is that not being careful in the sun can lead to skin cancer. That’s an absolute certainty.”

Some chemicals, however, might harm marine life. Hawaii has gone so far as to ban sunscreens containing oxybenzone and octinoxate, which are thought to damage coral reefs (perhaps explaining Zuckerberg’s unusual choice of zinc oxide while holidaying there this week).

Will a mask protect me from the sun, too?

In the era of coronavirus, you might think that a face covering provides a ready-made protection against sunburn, but much depends on the material. A “dense, dark” covering (like a scarf) will do a much better job of protection than a white, cotton surgical mask. If you are wearing the latter, you might still need to apply sunscreen beneath your mask.

“And you have to remember that half of your face is not covered with a face mask,” adds Dr Wedgeworth. “You don’t want people to think, ‘Well, I’ve got a face mask, I don’t need sun protection’.”

Ensuring that the rest of your face is adequately lathered will help protect against skin cancer, but will also stop you getting an unfortunate tan imprint, in which your forehead and cheeks come out tanned while the area beneath your mask remains unchanged. That would make you look even more foolish than Zuckerberg.

‘Don’t think, “Well, I’ve got a face mask, I don’t need sun protection” ’