4 Things You Didn’t Know About Sunscreen

Protecting yourself from the sun seems pretty straightforward: Just smear on some sunscreen and go. But judging from a new study, you’re probably doing it wrong. In a survey of 423 adults at New York City’s Memorial Sloan-Kettering Cancer Center, fewer than a third were aware that sunscreen should be applied 30 minutes before going outside (it takes that long for it to soak into skin and create a shield). And a mere 18 percent knew that you need a full ounce of the stuff, about two tablespoons, to adequately cover your bathing-suited body. These misunderstandings aren’t minor, says lead researcher Steven Q. Wang, MD—they mean you’re not properly shielded from the sun’s damaging rays.

His guide:


  • 1.

    Pick a sunscreen with an SPF of 50.

    That’s high enough to filter out 98 percent of the sun’s UVB rays—the ones that burn your skin. Using a product with a higher SPF can actually backfire, because these lotions allow you to stay in the sun longer without burning but don’t necessarily provide equally long-lasting protection against UVA rays—the tanning rays, which have also been linked to skin cancer. The FDA is changing its labeling rules to help clarify how well different sunscreens guard against all kinds of ultraviolet rays, but you won’t see the smarter labels on store shelves for a year or more.

  • 2.

    Check ingredients.

    Since SPF doesn’t tell you anything about UVA protection, look for 3 percent avobenzone paired with octocrylene. Or choose a sunscreen that contains zinc oxide or titanium dioxide.

    Don’t worry: Today’s formulas won’t give you a white “lifeguard nose.”

  • 3.

    Be generous.

    Squeeze out enough sunscreen to fill a shot glass.

  • 4.

    Apply often.

    You need to put on sunscreen 30 minutes before going outside, but don’t stop there. You lose protection when you sweat or swim or just rub your skin, so reapply every two hours.

Plus: Check out more summer safety tips.

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