Sun protection

What the sun actually delivers

Ultraviolet radiation arrives alongside the warmth and the light, at wavelengths shorter than the eye can see. It is absorbed by skin, and some of what it reaches is the genetic material inside cells. Most of that damage is repaired. What accumulates over a lifetime is what these pages are ultimately about.

Warmth is a poor guide to how much is arriving. A clear spring day can carry more ultraviolet radiation than a humid overcast one in high summer, because the angle of the sun and the state of the atmosphere drive it rather than the temperature does. This is the single most useful idea in this section, and also the least intuitive.

Protection is several things, not one

Sunscreen is the method everybody names first, and it is the one whose performance depends most on technique. Its stated protection comes from a test using a controlled quantity applied evenly, and almost nobody replicates that in a car park.

Shade, timing and clothing carry no such dependency. A hat is on your head or it is not. Published guidance treats these together for that reason rather than presenting one as the answer and the rest as optional extras, and one page here deals with each.

What is regulated and what is marketing

A sun protection label does two jobs at once without telling you which is which. Part of the writing carries a meaning defined by regulation; the rest is description chosen to make the product appealing. Learning to separate the two is most of what reading a label amounts to, and the skill transfers to every product on the shelf.

Cosmetic products in Great Britain, sun protection included, fall under a published regulatory framework. These pages point to it rather than restating it: requirements are precise, they are revised, and a paraphrase of a regulation is worth considerably less than the regulation.

Why there are no numbers here

You will find no factor thresholds, no exposure times, no index categories and no hours of the day on these pages. All of those depend on a country and a season, all are published by health authorities, and all are revised.

One fact about the ultraviolet index does appear, because it was verified against its source and carries the date it was checked: the index was developed jointly by four international bodies, which is why the same number means the same thing everywhere it is published. Everything else numerical is linked at source instead.

What a tan is, and is not

Colour appearing after exposure is melanin, produced or darkened in response to radiation that has already reached the skin. Two distinct processes are involved, one immediate and reversing within days, the other slower and lasting weeks.

Both are reactions to exposure that already happened, which is why health bodies describe the result as evidence of damage rather than as protection acquired in advance. Burning and tanning are not opposites either: they are two responses to the same radiation, on different timescales and to different degrees in different people. Someone who colours readily without turning red has still absorbed what produced the colour.

Skin tones are part of this, not a footnote

More melanin means more ultraviolet radiation absorbed before it reaches anything vulnerable, and that difference is real, partial, and frequently overstated in both directions. Skin cancers occur across all skin tones, and they have historically been recognised later in people with darker skin. One page here deals with the scales used to classify sun response and the documented criticism of them.

All sun protection pages

• How to read a sunscreen label

  What the wording on a sunscreen container refers to, which parts are regulated and which are marketing, and where the rules for Great Britain are published.

• Skin tones and how skin responds to sun

  What melanin does, why skin tones respond differently to ultraviolet radiation, what the classification scales were built for, and the documented criticism of them.

• Sun protection beyond sunscreen

  Why shade, timing, clothing and fabric matter alongside sunscreen, what makes a garment protective, and why relying on one method alone tends to disappoint.

• Sunbeds and what the guidance says

  What a sunbed emits, why health bodies advise against cosmetic use, how it differs from supervised phototherapy, and where the current guidance is published.

• What a tan actually is

  The two processes behind tanning, why sunburn and tanning are not opposites, and why health bodies describe a tan as a record of exposure rather than a protection against it.

• What the UV index actually measures

  What the UV index is a measure of, who devised it, why it is not a temperature reading, and why a cold bright day can carry more of it than a warm dull one.