We all know how important it is to slather on sunscreen before heading outdoors, but did you know that it's equally — if not more — paramount to apply SPF even when you're inside. Or that you really should be reapplying about every two hours?
Because the hard and fast rules of UV protection are often blurred, we've reached out to dermatologists to find out the truth behind sunscreen, when to wear it, and for how long.
1. Sunscreen should be worn daily, no matter your location — indoors and outdoors.
"Completely indoor activities don't require sunscreen, but many of us discount the sun that we get on a daily basis from just running errands and all the 'incidental' sun damage adds up," explains Elizabeth Tanzi, founder and director of Capital Laser & Skin Care and associate clinical professor, department of dermatology at the George Washington University Medical Center. "That's why we recommend daily sunscreen application, so you are always protected and don't have to think about it."
That means even if you spend most of your day indoors, says Ava Shamban, a dermatologist in Los Angeles: "Indoor UV exposure can occur from ultraviolet that penetrates through glass, which is UVA. UVA is emitted at the same level — all day long — where is UVB, which is blocked by glass peaks mid-day."
2. For everyday wear, sunscreen should be applied to the face, as well as other areas of concern.
Sunscreen should be worn on all over the face, ears included, recommends New York City-based board-certified dermatologist Debra Jaliman. "Cover your entire face with sunscreen, as well as your neck and hands," she says. "If you're not sweating a lot, you can just apply it first thing in the morning."
3. The magic SPF number is 30.
"The American Academy of Dermatology always recommends an SPF of 30, because it is clinically proven to be a sufficient amount of protection to reduce or minimize the adverse effects of sunlight," says David Colbert, a New York City board-certified dermatologist.
Joshua Zeichner, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City, adds that when used properly, there's little difference between a sunscreen with SPF 30 or something with higher protection.
"However, in the real world, we do not apply as much sunscreen as we should, and we do not reapply," Zeichner says. "This ultimately means that the SPF value is diluted out. Starting out with a higher SPF to begin with serves as a safety net to ensure the highest quality of protection for the longest period of time."
4. You should reapply every couple of hours.
"Ideally, sunscreen should be reapplied every two hours, or more frequently if you are swimming or sweating heavily," says Zeichner. "The best time to apply sunscreen is before you go outside because there are [fewer] distractions and you can make sure that you have adequately covered all exposed skin areas."
As for how much, Tanzi recommends about a thin layer on both the face and body, which equals a shot glass's worth for the entire body and a dime-sized dollop for the face.
5. Mineral sunscreen is dermatologist-recommend.
Blame it on chemical sunscreens' controversial ingredient list (and how it could be potentially harming the world's coral reefs), but dermatologists seem to all agree that mineral sunscreen is your best bet for sun protection.
"I really like mineral sunscreen formulas with zinc and titanium because they're natural ingredients," says Tanzi. "These physical sunscreens sit on the surface of the skin to deflect the rays." Even better, mineral formulas are better suited for those with sensitive skin, as they don't irritate the skin. We love the Best of Beauty 2019 winner for this. The Unsun Mineral Tinted Sunscreen SPF 30 is great because it leaves behind no white cast making it a winner for all skin tones.
6. Your clothes can count as SPF, too.
Sun protection doesn't just involve slathering on sunscreen. "Be sure to wear sun-protective clothing, hat, and sunglasses," says New York City board-certified dermatologist Amy B. Wechsler. "I know I sound like a maniac, but UV exposure is the number one cause of premature aging in the scan as well as skin cancer."
7. Your lips need protecting, too.
"People forget to protect their lips and skin cancer in this area can be particularly dangerous," says Tanzi. " Everyone needs lip balm with SPF." Our pick? The Supergoop Play Lip Balm SPF 30 with Acai, it's packed with rich shea butter and nourishing vitamin E.
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Originally Appeared on Allure