Making Sense of Suncare

After years of media and government campaigns about the dangers of over exposure to the sun, most of us are aware of the damage that it can cause to our skin. We know we should cover up, use sun cream, stay out of the sun during the hottest part of the day, wear sunhats, avoid sunburn and protect our children from sun exposure. Indeed, the received wisdom these days is that there is no such thing as a "safe tan."

This advice is simple to grasp. What is trickier to get to grips with is the vast array of sun creams, aftersun and other products out there. What do they do, and which is the right one to choose?

How do suncare products actually work?
Sun protection products reduce the amount of ultraviolet light that gets into skin when you go out in the sun, as Mike Brown, Boots suncare scientific adviser, explains: "They use active ingredients called sun filters which either absorb the ultraviolet (UV) light and convert it into safer infrared (which we feel as warmth), or reflect and scatter the ultraviolet light away from the skin."

So what's the difference between UVA and UVB?
The main UV rays found in sunlight are UVB and UVA. UVB is much higher energy than UVA and reaches the top layers of our skin. "As UVB stimulates the melanin in our skin, it triggers the development of a suntan," says Johanna Saiki, junior product manager at skincare products manufacturer Eau Thermale Avane. "It also sets off the synthesis of vitamin D. In the short-term, over-exposure causes sunburn, but in the long-term it is responsible for premature skin ageing and cancer."

UVA has less energy but penetrates deeper into the skin and damages the structural components of skin over time, which leads to wrinkling and can be responsible for skin cancer.

And what about SPF?
The sun protection factor (SPF) of a product is a measure of how well it protects the skin from burning. SPF ratings are calculated by comparing the time needed to produce sunburn on protected skin with the time needed to cause sunburn on unprotected skin, as Johanna Saiki explains: "For instance, a fair-skinned person who would normally turn red after 10 minutes in the sun has 10 minutes as their "initial burning time." If they use a sunscreen with SPF2, it takes 20 minutes in the sun for that person's skin to turn red. If they use one with SPF15, it multiplies the initial burning time by 15, so it takes 150 minutes to turn red, and so on."

However, there are two things to remember about SPF, warns Mike Brown: "The first is that SPF is reduced if you apply less product than recommended. The second is that SPF only measures the burning effect of ultraviolet light. Since the UVB component of sunlight causes most of the burning effect, the SPF is heavily influenced by UVB light and is not necessarily a good indicator of protection against the UVA light which contributes to long-term skin damage."

What does "aftersun" do?
Exposure to the sun dries out the skin, so the main job of an aftersun is to re-moisturize and soothe it.

But do aftersun products work any better than normal moisturizers? Mike Brown thinks they do: "There is plenty of data to show that aftersuns increase skin hydration really well. Many aftersun products also contain materials such as alantoin, aloe vera and so on, which have a cooling and soothing effect on skin."