How to walk under the sun and not burn out

In sum­mer, every­one is look­ing for a way to get to the beach at least for a while. But, as the per­son­al expe­ri­ence of our edi­tors shows, even one sin­gle day under the sun can turn into sun­burns that will “please” you for the next week. Obvi­ous­ly, quite a lot of peo­ple are fac­ing this prob­lem. Jour­nal­ists Sci­ence Focus We decid­ed to find out how sun­screen works and how to use it cor­rect­ly. With ques­tions, they turned to Bri­an Diffie, a mem­ber of the British Asso­ci­a­tion of Der­ma­tol­o­gists and Emer­i­tus Pro­fes­sor of Pho­to­bi­ol­o­gy at New­cas­tle Uni­ver­si­ty.

Should I use sunscreen in the shade?

Yes need. Ultra­vi­o­let is scat­tered in the atmos­phere. When you’re in direct sun­light, half of your UV radi­a­tion comes direct­ly from the star. The oth­er half hits your skin just from the atmos­phere. So even hid­ing under a canopy or a beach umbrel­la, you can still get burned, albeit twice as slow­ly.

Why is it so easy to get burned on the beach?

Many peo­ple think that it is easy to get sun­burned on the beach because the UV reflects off the sur­face of the water. It is not true. So lit­tle ultra­vi­o­let is reflect­ed from the sur­face of the water that it should not be tak­en into account.

The main rea­son is that the beach is open on all sides. If you are not hid­ing in the shade, then you get a full dose of ultra­vi­o­let — both the one that comes from the sun and the one that is scat­tered in the air. That is, in the desert or in an open field, you would burn out as quick­ly as on the beach, although there is no water there.

How to apply sunscreen?

On tubes, they usu­al­ly write that it should be rubbed into the skin, but do not write how much it needs to be done. Because of this, many peo­ple try to rub the cream almost dry. You don’t need to do this.

The job of sun­screen is to form a bar­ri­er between UV rays and the liv­ing cells of your skin. If you rub the cream too hard, it goes deep into the skin, and the top lay­er of epi­der­mal cells remains unpro­tect­ed. The cream does not need to be rubbed hard. It is enough to smear it on the skin and let it dry.

How much cream should be applied?

When cream devel­op­ers test the sun pro­tec­tion fac­tor (SPF), they focus on a vol­ume of 2 mil­ligrams per cen­time­ter of skin. This is a kind of inter­na­tion­al stan­dard that all man­u­fac­tur­ers fol­low. Unfor­tu­nate­ly, con­sumers do not fol­low this stan­dard.

Accord­ing to Prof. Diffie, peo­ple typ­i­cal­ly apply half as much cream as rec­om­mend­ed by the man­u­fac­tur­er (about 1 mil­ligram per cen­time­ter of skin). This is due to the fact that a lay­er of two mil­ligrams seems too thick to them. If you’re using sun­screen, you’re prob­a­bly smear­ing too much too. As a result, where the man­u­fac­tur­er claims SPF 30, in fact, there are from 10 to 15. But this is not a prob­lem. Pro­fes­sor Diffie rec­om­mends apply­ing the cream twice. The sec­ond time — after about half an hour, when the first lay­er dries.

Do I need to use sunscreen daily?

It does­n’t make any sense. In win­ter, sun­screen is def­i­nite­ly not need­ed. In sum­mer, it is worth using it only on the beach. If you spend half an hour a day on the street, on the way from home to work and back, then noth­ing bad will hap­pen to you with­out a cream.

Are expensive creams better than cheap ones?

No. Buy­ing a more expen­sive cream, you pay not for addi­tion­al pro­tec­tion, but for aes­thet­ics. A more expen­sive cream may smell bet­ter or spread bet­ter on the skin. But the pro­tec­tive sub­stances in expen­sive and cheap creams are the same.

Is a high SPF better than a low one?

I guess, yes. But it should be borne in mind that the high­er the SPF, the more dif­fi­cult it will be to smear the cream. Creams with a high SPF can be very vis­cous. There­fore, some­times it is more con­ve­nient to sim­ply apply a cream with a low SPF sev­er­al times.