Sun Safety by the Numbers

Harmful sun exposure can happen in just minutes. Read on for the numbers you need to know to avoid sunburn and prevent skin cancer all summer long.


Summer days beg for backyard barbecues, pool parties, and sand-filled beach trips. It's all fun in the sun—except for our skin. According to the Centers for Disease Control and Prevention, nearly one in three Americans suffer a sunburn each year, which immediately raises the risk for skin cancer. The problem isn't that we're completely clueless about shielding ourselves from the sun's harmful ultraviolet (UV) rays. Slathering on sunscreen and seeking out shady spots have become part of our warm-weather routine.

Where we slip up is in the details: Many of us are unsure how long to wait before slicking on more sunscreen, when to toss that half-used bottle, and what body parts are most vulnerable to solar radiation. This, in part, might explain why the rate of skin cancer in the United States remains stubbornly high. It's the most common form of cancer, affecting more people than breast, lung, prostate, and colon cancers combined. And its deadliest form, melanoma, is on the rise.

To save your skin, we asked top experts to spell out the need-to-know stats. Follow their sun-smart advice, and keep your family protected during all those fun times in the sun.

3 Months: How long it takes everyday sun exposure to break down collagen, the protein responsible for a firm, smooth complexion.

"This causes skin to lose its elasticity, resulting in wrinkles," says David Leffell, M.D., chief of dermatologic surgery at the Yale School of Medicine. He estimates that the sun is to blame for 80 percent of aging in the skin.

This includes not only sagginess, but also an uneven tone. As defense against solar radiation, the skin produces excess melanin, which shows up as brown spots.

Save your skin: All the antiaging creams in the world won't do much good if you don't use sunscreen daily. Get in the habit of putting it on every morning beneath your moisturizer and makeup. Combination lotions and foundations often don't have a sufficient amount of SPF; apply those in addition to straight-up sunscreen.

5 Years: How long it can take someone who frequents tanning beds to develop skin cancer.

The UV rays from those bulbs can be up to 12 times as strong as the sun, putting you on the fast track to disease.

"I see women in their early 20s with skin cancer, largely because they've visited tanning parlors since their teens," Leffell says. According to his research, tanning-bed use increases the risk of basal-cell carcinoma (the most common form of skin cancer) by 69 percent. Another study showed that it ups your odds of melanoma by 74 percent.

Just one trip to the tanning salon is harmful, so don't buy into the myth that building a "base" tan offers protection at the beach. Although you might feel safe because there's less of a burning sensation, the damage to your skin is already done.

Save your skin: For a healthy glow, try a self-tanner. But apply it a day before your excursion: A German study suggests that these products might leave your skin susceptible to UV damage for up to 24 hours following application.

5 Minutes: Time it takes your scalp to sizzle.

Even if you have a thick mane, those rays can sneak in and burn uncovered patches, like your part.

"Because the sun beats directly down on the scalp, it's one of the fastest places to burn," says Debra Jaliman, M.D., an assistant professor of dermatology at the Mount Sinai School of Medicine and the author of Skin Rules: Trade Secrets from a Top New York Dermatologist (St. Martin's Press). This might explain why 6 percent of melanoma cases occur on the scalp and neck.

Save your skin: Before heading out, spray your part, your neck, and the backs of your ears with sunscreen. During your monthly skin self-check (yes, this is something you should do), ask a family member to scan the top of your noggin for moles: Melanoma that develops on the head is among the deadliest, because it's rarely caught in the early and most treatable stages.

15 Minutes: The time it takes sunscreen to kick into action.

Today's formulas use chemical compounds such as avobenzone and oxybenzone to filter out UV rays. But in order for these ingredients to work, they first have to penetrate the skin, says Steven Wang, M.D., director of dermatology at Memorial Sloan-Kettering Cancer Center.

This waiting period is problematic for many moms: "All too often, you're chasing around your kids to get sunscreen on them, and then your husband asks you to put some on his back," Wang says. (Sound familiar?)

Save your skin: Slather sunscreen on everyone (including you!) at least 15 minutes before going out. If you're in a rush, use one made with zinc oxide or titanium dioxide to get instant protection. Rather than being absorbed into skin, these ingredients sit on the surface to block UV rays. These formulas have a thick consistency, but they're now available in clear so you don't have to sport a "lifeguard" look.

20 Minutes: How fast skin can get damaged from the sunlight passing through a window.

Because glass blocks UVB rays, you won't develop an obvious red flag, such as pinkness or a visible burn. This can create a false sense of security: More than half of UVA rays sneak through those panes, contributing to wrinkles and skin cancer. "Anytime you're in a sunlit office or car, you're exposed to UV rays," Jaliman says.

Save your skin: Even if you're stuck inside all day, remember to give yourself sunscreen touchups. Don't want to muss your makeup? Consider powdered sunscreen, which is applied with a built-in brush. Because the active ingredients in this mineral powder don't break down as quickly as chemical formulas, you can stash an extra in your purse or glove compartment.

20 Seconds: How long it takes to apply sunscreen to the bottom of your feet.

Much like the scalp, this area often gets overlooked, Wang says. But if you're wearing sandals or going barefoot, your soles are wide open to UV exposure.

Save your skin: Don't forget to slather or spray sunscreen over your entire foot, including the soles and between toes. While you're at it, scan for any suspicious-looking spots or moles: One in two people diagnosed with foot melanoma die within five years, often because the cancer is detected too late.

18 Minutes: Time it takes a fair-skinned person to develop a second-degree (read: blistering) sunburn on a bright day.

(It's 24 minutes for those with darker complexions.)

After waiting all year for vacation, you might be tempted to make a beeline for the beach. But even a quick dip sans sunscreen is dangerous. Research shows that intermittent exposure— short bouts of intense sun after spending most of your time indoors—is a stronger risk factor for skin cancer than everyday rays.

That's because a hefty dose of UV radiation triggers cancer-causing mutations while temporarily weakening the immune system—a double-whammy for skin cells. "Just one blistering sunburn may be enough to cause cancer down the road," Jaliman says.

Save your skin: The sun is most intense from 10 a.m. to 4 p.m. If you can't find a shady spot, make your own—a beach umbrella works. And apply sunscreen with an SPF of at least 30 and a "broad spectrum" label, which means that it shields against both UVA and UVB rays.

How much to apply? If you're in a swimsuit, squeeze enough to fill up your palm, and put on a fresh coat at least every two hours.

20 Minutes: How quickly you can get a sunburn on a gray day.

Don't be fooled by overcast weather: Even when sunshine is in short supply, up to 80 percent of UVA rays can pierce cloud cover. "It's possible to burn just as quickly on a hazy day as it is in sunny weather," Leffell warns.

Save your skin: No matter the forecast, don't forget the sunscreen. If you know you'll be spending time outside—say, at your child's soccer game or swim meet—stash a hat in your purse and a folding chair with a canopy in the car.

80 Minutes: Maximum time you can go without reapplying sunscreen if you're swimming or sweating a lot.

But that only holds true if you're sporting a sunscreen labeled "water-resistant (80 minutes)," according to FDA guidelines. If your bottle reads "water-resistant (40 minutes)," you'll need to reapply twice as often.

Save your skin: Restart the clock each time you towel off. "A lot of people go into the water for 10 minutes, dry off, then think they have 70 minutes left," Jaliman says. But along with those water droplets, you're also wiping away any remaining sunscreen. To play it safe post-swim, air-dry or reapply.

20 Minutes: Time it takes unprotected eyes to get sunburned.

Just as with skin, ultraviolet light can fry the cornea, the transparent tissue that covers the front of the eyeball, says Philip Rizzuto, M.D., a clinical associate professor of surgery at the Alpert Medical School of Brown University.

Inflammation develops several hours after sun exposure, triggering pain, irritation, and a temporary loss of vision. Called photokeratitis or ultraviolet keratitis, this condition resolves on its own within a few days.

Save your eyes: To protect your peepers—and fend off damage that leads to serious conditions such as cataracts and macular degeneration—slip on sunglasses. Look for a pair labeled to block both UVA and UVB rays (many only filter one type) in a wraparound style. And top it all off with a wide-brim hat. Besides looking glamorous, you'll safeguard against cancer in another location: the eyelids.

10 Weeks: Time it takes to build up sun protection from the inside out.

According to a review of research from Germany's Munster University Hospital, daily consumption of 90 milligrams (mg) of beta-carotene—the antioxidant found in red, yellow, and orange veggies—can provide your skin with a natural SPF of up to 4.

While this doesn't mean you can skip the sunscreen, it does provide a little extra protection and can lessen the damage of a burn if you do get one.

Save your skin: For the amount of beta-carotene used in the study, you'd have to eat 11 cups of carrots. Luckily, you don't have to chomp from dawn till dusk for your skin's sake. An easier route: Consider a 15 mg beta-carotene supplement. As with all supplements, check with your doctor before you start taking it.

3 Years: How long sunscreens remain fully effective.

Over time, active ingredients can break down. "But if you're applying the right amount, a 6-ounce bottle should only last for about six applications," Wang says.

Save your skin: Before you squeeze out the remnants of last summer's bottle, check its expiration date. If it's past its prime—or you can't recall when you bought it—toss it. Also, hot temps can cause compounds in chemical sunscreens to degrade, so keep your bottle in a cool space. At home, store it in a closet instead of on a sunny shelf.

5 Seconds: How quickly a tea bag can soothe the sting of a sunburn.

"Compounds in black tea called tannins act as an anti-inflammatory on the skin," explains Martina Cartwright, Ph.D., R.D., a nutritional scientist in Scottsdale, Arizona. This can tone down the redness and prevent peeling.

Soothe your skin: Steep a black tea bag in boiling water, let it cool, and dab it on your burn. Leave it on for two to five minutes; repeat this process several times through the day.

Still feeling the burn? Pop an aspirin and put on aloe vera gel or hydrocortisone cream. And whenever you step into the light, cover up with clothing.

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