You’ve heard it before: Wear sunscreen. It sounds like good advice, considering more than 1 million people will be diagnosed with some form of skin cancer this year, according to the American Cancer Society. Of those who get the diagnosis, nearly 10,000 cases will prove fatal. Yet questions remain about sun-care products and their use: How much protection do they really offer? Are they safe? For answers to these questions and more, check out our myth-busting guide to sun protection.

Myth #1: Sunblock and sunscreen are different names for the same product. Although both sunblocks and sunscreens protect your skin against the ultraviolet radiation that causes damage, they do so in different ways. Sunblocks, such as zinc oxide and titanium dioxide, form a physical barrier, reflecting the sun’s harmful UVA and UVB rays away from the skin. Sunscreens, on the other hand, are chemical blocks that include benzophenones and cinnamates. These chemicals work by absorbing and then scattering the sun’s rays, creating longer wavelength energy that is less damaging to the skin.

Most sunscreens protect against UVB, the burning rays definitively linked to skin cancer. Some of the newer sunscreens also guard against UVA. UVA, the rays that give us that golden glow, attack the connective tissue found in the deeper layers of the skin. Although a bronzed body might look great this summer, long-term exposure to UVA rays causes premature aging and wrinkles. More seriously, preliminary findings by researchers at the University of California, San Diego, suggest a link between increased UVA exposure and rising melanoma rates (Annals of Epidemiology, 2003, vol. 13, no. 6). For healthy protection, look for a broad-spectrum sunblock that guards against both UVB and UVA rays.

Myth #2: Sun-care products are the safest way to protect against skin cancer. The best way to safeguard your skin is to limit your sun exposure. Sun-care products aren’t a free pass to spend the day roasting by the pool. And slathering on chemically based sunscreens every couple of hours may have hidden dangers. According to one study conducted at the University of Zurich, Switzerland, many widely used sunscreen chemicals, including benzophenone-3, octyl methoxycinnamate, and octyl-dimethyl-PABA, mimic the effects of the female hormone estrogen. Normally, estrogen controls the growth of cells by attaching to proteins called estrogen receptors throughout the body. But in sunscreens, a variety of synthetic chemicals and natural plant compounds can attach to the estrogen receptor proteins in the same way, fooling the body by giving it an inappropriate “estrogen” signal. The end result could be potential developmental abnormalities (Environmental Health Perspectives, 2001, vol. 109, no. 3).

Scientists have also found that some sunscreen ingredients, such as avobenzone and padimate O, promote cancer by generating free radicals (Photochemistry and Photobiology, 2004, vol. 2, no. 1; Mutation Research, 1999, vol. 444, no. 1). Free radicals are unstable molecules that cause cellular damage by stealing electrons from healthy cells—a process called oxidation.

Fortunately, you can look for safer ingredients to help protect you from the sun. Zinc oxide and titanium dioxide, found in some sunblocks, are natural minerals that, when incorporated into creams and lotions, reflect the sun’s rays away from the skin’s surface. Often paired with antioxidants such as green tea (Camellia sinensis), Pycnogenol, and vitamin E, which prevent free radical damage, these minerals safely protect against UVA and UVB rays.

Myth #3: Avoid all sun exposure to be your healthiest. Although overexposure to the sun can bring on wrinkles, and sizzling sunburns can lead to skin cancer, your body does need some sun every day to manufacture vitamin D. This vitamin keeps bones and teeth strong and helps protect against breast, prostate, and colon cancers. “When wearing sunscreen, you prevent the synthesis of vitamin D—even more than you prevent skin cancer,” says Cedric Garland, DPH, adjunct professor of family and preventive medicine at the University of California, San Diego, School of Medicine. Luckily, boosting vitamin D levels doesn’t require hours in the sun. According to Garland, spending just 10 to 15 minutes in the sun each day without sunscreen, preferably outside the sun’s strongest hours of 10 a.m. to 4 p.m., will give your body all the vitamin D it needs.

Zinc oxide and titanium dioxide are natural minerals that reflect the sun’s rays away from the skin’s surface.

Myth #4: People with dark complexions don’t need to worry about sun protection. Fair-skinned folks do burn faster than people with darker skin, but it’s a good idea for everyone to wear some form of sun protection every day. How much? Most dermatologists suggest using a product with a minimum rating of SPF 15, regardless of skin color. SPF, or sun protection factor, is a gauge for how long you can safely stay out in the sun before burning. “If, without any sunscreen, you would burn after ten minutes of exposure, an SPF 6 sunscreen would protect you six times longer,” explains David Stoll, MD, a Beverly Hills, California-based fellow of the American Academy of Dermatology in Schaumburg, Illinois.

Myth #5: The sunscreen in makeup protects you, so you don’t need additional sun-care products. The sunscreen in your moisturizer, foundation, or lipstick probably isn’t adequate. Some cosmetics offer SPF 8, tops—not nearly enough to guard against the sun’s harmful rays while driving or walking, let alone during a day at the beach. Applying sun protection of at least SPF 15 before you put on your makeup gives you an added layer of safety. If you’re planning to spend the day outdoors, Stoll recommends using 1 ounce of sunscreen (the equivalent of one full shot glass) on all of your exposed parts. And reapply it often—at least every two hours.

Writer Kim Erickson is the author of Drop-Dead Gorgeous (Contemporary, 2002) and a frequent contributor to Delicious Living.