As we approach summer, now is a great time to talk about sunscreen. I’m going to run through some of the basics as to what SPF is, how sunscreen works, and how to choose the right sunscreen.
What exactly are we screening?
Sunscreen products combine different ingredients to protect our skin from UVA and UVB rays. UVB are the ultraviolet rays that cause our skin to redden and eventually burn. UVA rays are widely used in tanning beds, but are also responsible for the premature aging of the skin including wrinkling and leathering and penetrate the skin deeper than UVB rays. UVB rays tend to damage more superficial layers of our skin. Both contribute to our risk of skin cancer.
So, WTF is SPF?
SPF stands for Sun Protection Factor. It is not an ingredient, and it is not good or bad in and of itself. SPF is just a measurement that helps inform us on how to best protect our skin from the number one culprit in skin damage, the sun.
What do the numbers mean?
The number that follows SPF on sunscreen bottles indicates how long your skin is protected from the sun. An SPF 30 product will protect your skin 30 times longer than going without sunscreen. So, in theory, if it takes your skin 10 minutes to burn unprotected, it will take 5 hours to burn with SPF 30 sunscreen.
As a measurement of strength, the difference between an SPF 30 and SPF 50 is pretty small. SPF 50 does block 1.3% more rays than SPF 30, though, so if you’re extra sensitive or have a history of skin cancer, this small increase in protection will make a difference.
The percentage of rays that SPF factors block are as follows:
- SPF 15 – 93%
- SPF 30 – 96.7%
- SPF 50 – 98%
- SPF 60 – 98.3%
- SPF 100 – ~99%
No sunscreen will block 100% of UV rays.
The problem with SPF?
SPF is misleading because you should not expect any sunscreen product to be fully effective longer than two hours without reapplying. Even if you’ve got SPF 50 on and don’t burn easily, you still need to reapply regularly to properly protect your skin.
Also, while sunscreens can be water-resistant, none are waterproof. In 2011, the FDA decided to ban the use of the words “sunblock”, “waterproof” and “sweat-proof” in sunscreen products due to their inaccuracy. If you’re spending time in the water or doing physical activity that causes you to sweat, you’ll have to reapply even more often, because the product will eventually wear off.
Lastly, SPF only measures protection against UVB rays. This is important to note when choosing a sunscreen product, as UVA rays are even more penetrating than UVB rays. Look for a sunscreen with UVA-screening ingredients like zinc dioxide or titanium dioxide to get the best protection.
A great natural sunscreen I’ve been using lately is Weleda’s Edelweiss Sunscreen. It protects against both UVA and UVB rays with an SPF of 30. The packaging says it’s “ultra-waterproof” but, as I just mentioned, no product can be fully waterproof.
The “non-nano” mineral UV filters means that the product does not contain particles small enough to soak into the skin. I haven’t found any compelling evidence, however, that nano particles of zinc dioxide or titanium dioxide absorb beyond the dermal layer.
Sunscreens made with non-nano particles (like this one) do provide better protection against UVA rays, though, which is great.
What’s right for me?
A good rule of thumb is to always choose a product that has an SPF of 30 or higher and one that protects against both UVA and UVB rays. If you don’t see UVA or UVB on the product, good keywords to look for are “broad spectrum”. This means you’re getting protection against both UVA and UVB.
Any product with less than SPF 15 is not going to provide enough protection, while those over SPF 50 offer an extremely negligible increase in protection and are often misused and under applied.
And even if you’re in cloudy, gray Helsinki like me, the same rules apply. You don’t have to be at the beach to need protection from the sun; in fact, you should be wearing sunscreen everyday.
What’s your favorite sunscreen product?