(ABC News) -- If we lived in pristine, temperature-controlled labs, SPF 15 would be adequate—if not optimal—protection against sunburn (caused by UVB rays) and skin aging and cancer (caused by UVA and UVB rays).
But we live in the real (sweaty, splashy, windy) world, and we don't use as much sunscreen as we should. In fact, the protection most of us get from SPF 15 is more like SPF 3 to 7. That's why the American Academy of Dermatology recommends using broad-spectrum SPF 30.
1. What's the Highest SPF?
What's the highest SPF that's legit? I heard it's 50, so why do I see products with much higher numbers? —Veronica Walters, 33, Bensalem, PA
If you apply sunscreen correctly (see question 3), SPF 50 offers the maximum protection necessary. You're seeing SPF 80 and even SPF 110 on shelves because of "marketing, marketing, marketing," says Bruce Katz, MD, a dermatologist in New York City. Companies know that higher numbers make you think you're getting a significant surplus of protection, even though you're not. But the FDA has caught on to this strategy and proposed a rule making "50+" the highest SPF value allowed. The rule hasn't been approved yet, but many manufacturers are probably betting it will—they're already distributing products labeled SPF 50+, even as they continue to sell higher numbers.
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2. Should I Protect My Hair?
Are sun-protective hair products a waste of money? —Joan M. Blewitt, 59, Kingston, PA
The sun can change your hair color, but products with UV filters or antioxidants may keep your hue from fading or turning brassy. If you like the color you've got (or spent good money to get it), a spray like Paul Mitchell Sun Shield Conditioning Spray ($18; paulmitchell.com for salons), shown above, helps. Will it prevent cancer? No—and cancer commonly forms on the scalp, says Dr. Katz. You should still wear a hat or use traditional SPF on your part (or your entire scalp if your hair is thin).
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3. What's the Right Way to Apply Sunscreen?
What are the basic rules for applying sunscreen? –Marijo Elias, 53, Kingston, PA
30: The minimum SPF you should use (other must-haves water resistance and a broad spectrum formula).
20: The number of minutes before you go out in the sun that you should apply sunscreen. That is, unless your lotion has titanium dioxide or zinc oxide, which are effective immediately.
2: The number of hours you can go without reapplying if you're not sweating or in the water.
1: The number of ounces you need to coat your body with enough product (a 0.002 mm layer) to provide the SPF listed on the label. If you're using lotion, that's about the amount that would fill a shot glass; if you're using a clear, continuous spray, that's 30 to 90 seconds of spraying—enough to create a visibly glossy sheen as it goes on.
4. How Do I Keep Sunscreen Out of My Eyes?
I hate it when I'm outdoors or exercising and my eyes start stinging from drippy sunscreen. What are my options? —Rachel Aydt, 40, New York City
That burning is usually caused by chemical sunscreens (ingredients listed on the Drug Facts label that end with-ate,-ene, or-one, such as ho-mosalate, octocrylene, or oxybenzone). Instead, look for a water-resistant product with physical (sometimes called mineral or natural) sunscreen, such as zinc oxide or titanium dioxide. Even with those guidelines, it can take time to find the right formula, since fragrance can also sting. We tried a few dozen, and the clear-eyed winner was—MDSolarSciences Natural Mineral Sunscreen Stick SPF 40 ($13; mdsolarsciences.com).
5. How Long Does SPF Last?
How long does the SPF in my moisturizer last? —Lara Mitchell, 34, Philadelphia
If you don't plan to work up a sweat or be outside long, the protection should last 2 to 4 hours, says Amy Wechsler, MD, a dermatologist in New York City. However, if you work outside or plan to spend the day in the garden or at the beach, you really need a water-resistant face sunscreen in addition to—or instead of—your moisturizer. Try one of the new lightweight, liquid sunscreens (they come in small bottles you need to shake before using); L'Oréal Paris Sublime Sun Liquid Silk Sunshield for Face SPF 50+ ($11; drugstores) smoothes on as easily as moisturizer and has anti-aging antioxidants to boot.
6. How Should I Get My Back?
Any advice for applying sunscreen to your own back? —Donna Joy Dickinson, 57, Shavertown, PA
Reaching up and over your shoulder, you should be able to get the job done with a clear, continuous spray that works upside down. Aveeno's HydroSport Sunblock Spray SPF 30 ($10; drugstores) propels about 2 feet and should reach even the center of your back. If you're not flexible enough for the reach-over, slip on a tank top with UPF (ultraviolet protection factor). You can make your own by washing a top you like in SunGuard ($2; sunguardsunprotection.com); it coats clothing with an un-detectable layer of UPF 30 that lasts up to 20 washes.
7. Can I Get Skin Cancer Again?
I was diagnosed with a basal cell carcinoma, and it was removed. My doctor says I have to be even more careful about sun protection. Why? —Amanda Bosca, 65, New York City
Skin cancer survivors are much more likely to develop a second skin cancer, says Erin Gilbert, MD, PhD, a dermatologist in New York City. That's because they've already accumulated enough UV harm near the original cancer (dermatologists call it field damage) to make getting another likely. For survivors, skin exams every 6 months are essential. Everyone else should get one yearly—sooner if you have a suspicious mole.
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8. Can My Diet Make Me Burn Less?
I've been trying to eat healthier, and as my diet gets cleaner, I seem to burn less. Why would that be? —Jennifer Allard, 42, Newburyport, MA
Certain nutrients, especially phytochemicals, improve skin's ability to ward off damage. One study found that supplementing with lycopene (a pigment in red fruits and vegetables) may prevent UV damage; another showed that people taking a supplement with alpha-and beta-carotenoids (in orange and yellow produce) were less likely to have skin damage after UV exposure. It's possible eating a rainbow could delay sunburn, but that doesn't mean a salad is equal to sunscreen.
Be on the lookout for an SPF pill: British scientists are working to create sunscreen in pill form, after discovering that coral in the Great Barrier Reef creates its own UV protection by consuming a compound in algae. Human testing hasn't begun yet, but someday we may be able to swallow our sunscreen.
9. Does Sunscreen Affect the Fish?
Is sunscreen residue bad for marine life? —Elizabeth Rosen, 46, Madison, WI
Yes. Some ingredients in sunscreen can awaken viruses that kill coral's food supply—and ultimately the reefs themselves and the animals that live there. The common ingredients that are most damaging include oxybenzone and the preservative butylparaben. For an eco-friendly option, choose a product that uses the physical sunscreen ingredients zinc oxide or titanium dioxide because they "break down more readily in nature," says Ni'Kita Wilson, a cosmetic chemist in New Jersey.
10. Special Sunscreen for Rosacea?
I have rosacea. Should I be using regular sunscreen on my face, or do i need something special? —Reisel Weinberger, 67, Merion Station, PA
Rosacea makes skin sensitive and more likely to react to certain ingredients in sunscreen—but the sun itself is one of the biggest flare-up triggers, so going unprotected is not an option. Robin Schaffran, MD, a dermatologist in Los Angeles, suggests avoiding chemical sunscreens, and Dr. Wechsler also tells her patients with rosacea to say no to fragrance. Neutrogena Pure & Free Liquid Daily Sunblock SPF 50 ($14; drugstores) is a good option. Or try Colorescience Sunforgettable Face Primer SPF 30 ($50; colorescience.com), which has a tint that helps hide redness.
11. A Non-Goopy Natural Sunscreen?
Can you recommend a natural sunscreen that doesn't look like toothpaste? —Christine Bossi, 42, Kingston, MA
The purest options are those without chemical sunscreens, retinyl palmitate, fragrance, or para-bens. That leaves products that use physical sunscreens, which typically don't rub in as easily and sometimes leave skin with a whitish cast. After trying pretty much every natural sunscreen that meets these guidelines (for a list, go to prevention.com/natural sunscreen), we found the least toothpasty, most pleasing picks were Banana Boat Natural Reflect SPF 50+ ($11.50; drugstores) and All Terrain TerraSport SPF 30 Spray ($14; allterrainco.com).
12. Should I Wear SPF Clothing?
Is there any reason to wear sun-protective clothing? —Redd Becker, 55, Bellingham, WA
As Leeann Brown, a spokesperson for the Environmental Working Group, wisely points out: "Even the best sunscreens should not be your primary defense against the sun—minimizing time outdoors, seeking shade, and wearing protective clothing, hats, and sunglasses are going to be more effective than sunscreen alone." Unfortunately, not all clothing protects against the sun. White cotton only has about UPF 5 or 7 (UPF is like SPF, but for clothes); colored cotton has UPF 10; and heavy black velvet or dark blue denim can have up to UPF 50. But, really, who wants to wear head-to-toe denim—not to mention velvet!—in summer? Instead, look for sweat-wicking clothes with at least UPF 30; Athleta, Columbia, and Patagonia all have great options.
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13. Can Chemicals in Sunscreen Hurt Me?
I know too much sun can cause cancer, but aren't the chemicals in sunscreens unhealthy too? —Bonny Laneski, 50, West Wyoming, PA
Use the sunscreen. Although a few studies have raised questions about the safety of oxybenzone and retinyl palmitate, two ingredients found in some sunscreens, they are entirely avoidable if you read labels. So, what are potential concerns about those two components? Oxybenzone has been shown to cause hormone disruption in studies of cancer cells (however, a study on its effect when applied to skin did not show any statistically significant change in hormone levels). Retinyl palmitate has been linked to skin cancer when applied topically in very large doses to mice (however, the species of mice used in the study were far more susceptible to skin cancer than humans, and there aren't any human studies showing the ingredient causes cancer, according to Steven Q.Wang, director of Dermatologic Surgery and dermatology at Memorial Sloan-Kettering Cancer Center in Basking Ridge, NJ).
14. Will I Still Get Enough Vitamin D?
I want to make sure I get enough vitamin D. Does it still get through if I wear sunscreen? —Anne McNicholl O'Connor, 50, Montreal, Canada
When you have sunscreen on, your body's ability to produce vitamin D—which keeps bones healthy and may prevent some forms of cancer—is inhibited. "But even people who are very good at using sunscreen almost never wear enough of it enough of the time - to prevent adequate vitamin D production," says Robin Schaffran, MD, a dermatologist in Los Angeles. Even if you were to wear sunscreen every single day, it's highly likely some UV light is still getting through. If you're worried you're not getting enough vitamin D from your diet, all the experts interviewed for this article recommended the same thing: "Take a supplement." A daily dose of 600 IU daily should do it.
15. Are Sport Formulas Really Waterproof?
Are sport sunscreens really waterproof? —Beth Scarnati, 33, Los Angeles
First, ignore the word sport on labels; it may imply some sort of water or sweat resistance, but the government doesn't regulate the use of the term, so you can't be sure. What you can be sure of is this: "No sunscreen is truly waterproof or sweatproof," says Dr. Katz. That's why in June 2011, the FDA passed a rule banning the use of the terms waterproof and sweatproof. After a June 2013 deadline, the most water-and sweat-resistant sunscreen you can get will be labeled "water-resistant (80 minutes)," like Coppertone Sport Pro Series SPF 50+ ($11; drugstores). Some sunscreens may continue to use the term "sweat-resistant" as well, but even if they don't you can assume the water-resistance will keep you protected through 80 minutes of heavy sweating, too. (After all, perspiring can make your skin as wet as if you took a dip in the pool!)