You want to be sun-safe, but sunscreen labels are confusing. SPF, UVA, and UVB. Is higher SPF in sunblock better? We’ll explain the science so you don’t get burned. Summertime means fun in the sun, but this season the U.S. Senate is turning up the heat on the Food and Drug Administration. Senators want the FDA to lay down the law on sunscreen labeling. Anything over SPF 50, lawmakers say, should just be labeled as SPF 50+. Why? Sunscreen protection pretty much tops out there. Numbers higher than SPF 50 are just misleading. And probably a waste of money. Wait! So my SPF 70 spray here isn’t extra awesome? I was always taught that more is more. Well, it’s complicated. Allow me to shed some light on sunscreen chemistry.
What is SPF? Is higher SPF in sunblock better?
SPF stands for for sun protection factor. Think of a layer of sunscreen like a really thin bulletproof vest. And the sun’s rays as a barrage of bullets. Sunscreens absorb or reflect UV radiation from the sun. Before it can penetrate your skin and give you a sunburn or, even worse, skin cancer. Chemists have a measurement called absorbance. In the lab, you can shine a light on something and then figure out how much of that light comes through the other side. You can test sunscreens the same way. You’d think that SPF 30 would have two times as much absorbance as SPF 15, but it doesn’t. And look! SPF 50 isn’t that much better than SPF 30. We’re maxing out here. Here’s another way of looking at it. After SPF 50, you’re barely getting any more bang for your buck. Sky-high numbers might make you think you’re safer, but the evidence says otherwise. You should also know that no sunscreen blocks 100% of UV rays.
SPF measures the effectiveness against UVB rays only
And one last thing. SPF only measures how effective sunscreen is at blocking UVB rays. UVB rays are the primary cause of sunburn, but UVA rays penetrate even deeper into your skin. They’re linked to premature aging and skin cancer and play a role in sunburn, too. Experts have yet to agree on a system for measuring UVA ray protection. For now, there’s a pass/fail test. If a sunscreen passes, it gets labeled broad spectrum. So remember: Apply plenty, reapply often, and don’t waste your money on anything over SPF 50.
Higher SPF does not mean better protection at all. Higher numbers in SPF are confusing. Only by experiment, you can know how much SPF 50 is more protective than SPF 15. It can be slightly more protective or even the same. Only by experiment, you would know.
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