Which SPF Should You Wear?

What a. summer we've had so far. We've had heatwaves, mini heatwaves and now the Home Counties are on course for their joint driest June on record ever as we continues to enjoy the very sunny weather. With good weather at home and sun holidays booked, attention invariably turns to thoughts of boosting vitamin D levels and adding a glow to our skin. We all know that too much sun = a much higher risk of skin cancer, and we all know better than to head out for a day’s sunbathing without wearing any protection. But then there’s the question of sunscreen. What SPF should you wear? If your make-up has an SPF in it, is that enough? How often should you reapply it? Is sunscreen actually full of toxic ingredients? And what the hell does “broad spectrum” mean?

We spoke to a leading dermatologist about how best to protect your skin from the sun.

A lot of confusion about sunscreen tends to stem from this one fact. There are two different types of UV rays from the sun – UVA and UVB – and they work in different ways. “UVB has a shorter wavelength but has higher energy,” explains Dr Stefanie Williams, a cosmetic dermatologist and founder of Eudelo clinic in London. “It has more aggressive effects on the skin, but it is filtered out quite easily.”

UVB rays are the famous ones; they cause your skin to burn, and they are what SPF protects you from. They’re are often filtered out, for example by glass (you don’t get sunburnt if you’re sitting next to a window on a sunny day), and to a certain extent by clouds (but not totally – you can definitely still get badly burnt on a cloudy day; I tell you this from painful experience.) “In theory, SPF15 absorbs about 93% of UVB rays, SPF30 absorbs 97% and SPF50 absorbs 98%,” explains Williams.

UVA, on the other hand, is what makes your skin age prematurely. Dr Williams explains, “It’s lower energy but it gets much deeper in to the skin to where the collagen is developed in the dermis. It is not filtered out by glass, so we still get UVA for example through the window.”

Both types of UV have been linked to the development of skin cancer, so protecting from these UV rays isn’t just a matter of wanting to look good as you age – it’s for your health.

In fact, some products with an SPF in don’t protect from UVA rays at all. The words you want to look out for are “broad spectrum” – that means that product protects you against UVA rays as well as UVB. You’ll notice that although a lot of your make-up might say it contains an SPF, it isn’t broad spectrum.

Then, even when you’ve got your hands on a sunscreen or day cream with a broad spectrum SPF30, you still don’t know how much protection from UVA rays you’re getting. SPF only tells you how well a product protects you from UVB rays.

“In my opinion one of the best indications about a product’s UVA protection level is its PPD rating (persistent pigment darkening), which unfortunately is hardly ever displayed on the packaging,” explains Dr Williams.

Now, if that wasn’t complicated enough, there are several different labelling systems to indicate how well a product protects you from UVA rays. Helpful, right? Some are more confusing than they’re worth – for example, there’s a star-based system that rates the ratio of UVA to UVB protection, rather than just the UVA protection.

The symbol to look out for on packaging is the PA+ sign. This system indicates the level of PPD in the product; PA+ is low (PDD of 2-4) and PA++++ is highest (PDD 16 and over). Dr Williams recommends an SPF of at least 30, and PA++++ for the best protection from sun damage.

That’s only if you put enough on, mind. “Research has confirmed that under normal conditions we tend to apply less than half the recommended amount,” Dr Williams says. “So in daily life, we hardly ever reach the SPF factor stated on the packaging.”

There is occasionally a flurry of concern that some chemical ingredients found in sunscreens could be toxic or harmful to skin. First of all, as any doctor will attest, the sun is going to do far more damage to your skin than sunscreen is, so wear it.

Oxybenzone is a UV filter that’s often in chemical SPFs and is one of the ingredients that tends to raise concern. In 2012, the Environmental Working Group in USA published a Sunscreen Guide recommending that people not use sunscreen containing oxybenzone as it “is linked to hormone disruption and potentially cell damage.”

But Dr Williams says there isn’t any clinical evidence to prove that. “I think the jury is out on that,” she says. “I’m not a fan of oxybenzone anyway, but if there was any confirmed damage then the FDA [and other regulators] would be looking into stopping it. There’s no confirmation on any of that.”

However, research in 2012 by Heretics Environmental Laboratory in USA did suggest that oxybenzone damages the growth of coral, so if you’re planning on swimming in exotic waters, think about what’s in your suncream.

Dr Williams also dismissed any concerns about another chemical sun filter: retinyl palmitate. “It’s just another type of retinol, a derivative of vitamin A. It’s a milder form which doesn’t do as much.”

Dr Williams says that while she doesn’t have a problem with chemical sun filters in sunscreen, she does prefer the physical filter – the ingredients that literally sit on your skin blocking UVA and UVB rays from getting in. “Zinc oxide and titanium dioxide,” she explains. “Especially for children and for people with sensitive skin, I prefer physical sun filters.”

Of course there’s a down side to this militant vigilance when it comes to sun protection: you don’t get much of a tan. “Tan in fair skinned people is a sign that your skin has been damaged. And if you are protecting yourself well enough, you shouldn’t be getting that much of a tan,” says Dr Williams. “Last year, I was on holiday in Egypt with my family, and at the end of the holiday, people were asking if we’d just arrived, because we were so white.”

Better book in for a spray-tan, sharp.