SPF, UVA, UVB AND EVERYTHING ELSE YOU NEED TO KNOW ABOUT SUNSCREEN
Carla Valois Lobo
Warm days makes us happier. Long evenings with friends at the park; Cocktails and Pimm’s at the pub; and highly planned, yet surprising weekends in a Greek or Spanish beach. Summer offers it all but it also demands more caution with your skin. It’s perfectly fine to enjoy milder temperatures outdoors, however if you want to keep your skin healthy you’re better off using sunscreen. And that’s where the dilemma starts: do you really know what it means SPF, UVA, UVB or what’s a chemical or physical filter?
As a matter of fact, most of us are not aware of what kind of sun protection we should look for or even what is SPF. For instance, only 8% of 2,000 British adults recently surveyed by the Royal Pharmaceutical Society knew what SPF rating stands for. But, fear not: we researched everything you need to know about sunscreen and clear it up for you.
UVA x UVB
UVA and UVB, or ultraviolet A and ultraviolet B, are the two types of damaging rays emitted by the Sun that reach Earth’s surface – UVC rays are absorbed previously by Earth’s atmosphere, and they don’t come any near us. UVB rays are the main cause of reddening and sunburn; they play a major, decisive role in the development of cancer and they directly harm our DNA.
UVA rays lead to skin’s premature ageing, inducing dark spots, enlargement of blood vessels, and wrinkles. Indirectly, they also damage our DNA as they easily penetrate the epidermis. Although UVA rays are less harsh than UVB rays, they’re able to prompt cancer as well.
It’s worth mentioning that UVA rays can pass through window glass, whereas UVB rays are mainly blocked by it. According to the Skin Cancer Foundation, UVA rays present approximately equal intensity throughout the year and they account for 95% of the UV radiation that reach us.
SPF literally means sun protection factor. Although it sounds pretty clear, most of us don’t know what SPF really is or even that it protects us only from UVB rays. A high SPF rating does not imply full-spectrum protection as it does not block UVA rays, which are usually rated by stars (five-star products deliver the highest percentage of UVA protection).
Interestingly, the SPF rating is measured by how long it takes for UVB rays to reach and burn our skin. For instance, someone using a sunscreen rated SPF 15 will take 15 times longer to redden than someone not wearing any kind of sun protection. The difference between SPF 15, 30 or 50 is not big though: a SPF 15 blocks 93% of sun’s UVB rays, whereas SPF 30 and 50 protects us against 97% and 98%, respectively.
“No sunscreen can block 100% of sun’s rays”, warns the American Academy of Dermatology via its website, also alerting that “high-number SPFs last the same amount of time as low-number SPFs”. Here in the UK, as in Australia and the US, brands can’t label their products higher than SPF 50+.
PHYSICAL PROTECTION x CHEMICAL PROTECTION
Sun protection can be achieved via chemical or physical sunscreens. Products formulated with titanium dioxide and zinc oxide are physical blockers. They work by reflecting UV light away from our skin and they offer full-spectrum coverage. Chemical filters are usually made with active ingredients such as metoxyl, triazine and several others ending with -benzone and -salate (i.e., oxybenzone, dioxybenzone, and homosalate). A chemical sunscreen work by forming a protective layer on the epidermis; it absorbs the UV light before it penetrates the skin.
Often chemical sunscreens sink faster on the skin and dry transparently, whereas physical sunblocks usually leave a light, thin white film on it but are more suitable for sensitive skin. Despite chemical sunscreens being abosrbed quicker they need to be applied at least 20 minutes before you go outdoors. Keep in mind you should reapply sunscreen every two hours though – it doesn’t matter if you’re wearing a physical or a chemical filter, they don’t retain their effectiveness longer than two hours.
CREAM, GEL OR SPRAY?
Texture-wise, sunscreen is generally manufactured as a cream, gel or spray. The best texture however is the one suits you best, it’s a matter of personal choice. If your skin is blemish-prone or dry, we would recommend creams, especially for the face. Sprays are good for wilder areas, such as arms, chest and legs, while gel-like products are perfect for hairy areas.
Regardless of which texture you choose, make sure your sunscreen is water-resistant and has full-spectrum coverage.
On the gallery below we enlisted our favourite face sunscreens: