9 Sunscreen Booby Traps to Avoid

Think you know how to protect yourself and your family from the sun's damaging rays? Think again. Skin cancer (read more about skin cancer) is the most common type of cancer, probably making up more than half of all diagnosed cases of cancer, according to the American Cancer Society (ACS). The good news is that about 90 percent of all skin cancers could be prevented by properly protecting yourself. Get your facts straight so you—and your family—can safely enjoy the great outdoors all year long.

4 big mistakes with big consequences:

Relying on sunscreen (or sunblock, or suntan lotion) for protection: Too many people think that using sunscreen will allow them to remain in the sun all day without burning. Experts agree: Using sunscreen isn't enough. In addition to using the right sunscreen properly, shade yourself with a beach umbrella and wear closely woven brimmed hats and clothing (preferably made from fabric treated for UV protection). Don't forget your eyes! Wearing wrap-around sunglasses with UV-screening lenses will help protect your precious peepers (read more on eye health).

During the hours of 10 a.m. and 4 p.m., when the UV light is strongest, try to avoid the sun altogether. Not watching the clock? The "shadow rule" can help: avoid the sun when your shadow is shorter than you are—that's when the sun is strongest.

Using the wrong sunscreen: According to the Skin Cancer Foundation, there are six main skin types, from very fair to black, and each has differing risks of enduring sun damage that can cause cancer.

Different skin types need sunscreens with varying SPF (sunburn protection factor) ratings. The American Academy of Dermatology advises, in general, choosing a sunscreen with at least SPF 15. Very fair people—who burn easily and often suffer bad sunburns—should choose higher SPF numbers such as 30 or 45. That doesn't mean, as some people think, that they can use SPF 45 and stay in the sun 45 times longer than without sunscreen coverage. It's estimated that SPF 45 provides only 3 to 4 percent more protection than a SPF 15.

According to Dr. Taylor, the founder of brownskin.net, an online dermatological resource for women of Asian, African, Latin, Native American, Pacific and other native descents, skin pigment, or melanin, in the "average" African American gives protection equivalent to SPF 13, but that brown- and black-skinned people should still use sunscreen with as least SPF 15. Think of it this way: although it's not exactly additive, (SPF) 13 plus 15 equals 28, or close to (SPF) 30.

Using too little sunscreen: If you're lucky, you might find 8-ounce bottles of sunscreen, but many of the products sold today contain only 4 ounces or less. For adequate coverage, an "average"-sized adult needs to use one ounce of sunscreen (about the amount that fills your palm or a shot glass) each time they apply it. Larger people will need more. Sunscreen needs to be reapplied every two hours. If you're swimming or playing a sweaty sport, you need to apply it immediately after drying off.

When you do the math, you'll quickly see that if sunscreen is applied correctly, one 8-ounce bottle shared by a few family members or friends won't last past lunchtime, if that. The American Cancer Society (ACS) stresses the importance of applying sunscreen 15 to 20 minutes before going outside to let your skin absorb it. The ACS also recommends using sunscreen even on cloudy days. Also, use lip balm containing sunscreen.

Relying on only SPF numbers: Do you purchase sunscreen based only on SPF number listed on the bottle? Next time you're shopping, you may want to take a closer look at the label. SPF only measures UVB (ultraviolet-B) radiation protection, not UVA (ultraviolet-A) protection. Both types of UV light lead to skin damage and cancer so it's vital that sunscreens protect from UVA as well as UVB. Make sure the product specifies protection from both or says "broad-spectrum" on the label.

5 other sunscreen booby traps to know about:

• Despite advertising claims, no sunscreen is "waterproof" or "sweatproof," according to the FDA. "Water resistant" sunscreens must be reapplied after 40 minutes of sweaty activity or swimming.
• As crazy as it sounds, certain sunscreen ingredients break down in sunlight! Some ingredients also break down over time, the FDA says, and that deterioration may be speeded by sun exposure. So throw away last year's bottles and keep your sunscreen in a shaded spot when outdoors. The Environmental Working Group, a public health advocacy organization, found that 54 percent of sunscreens contain ingredients that become unstable when exposed to light and might not offer the advertised protection. The group lists what it deems the "best" sunscreens here.
• Don't look for "sunblock." The FDA states that no product completely blocks UV rays. "Sunscreen" is a more accurate term.
• Watch out for human error and don't be frugal with sun protection. "Most sunscreen users still get burned because they do not apply enough sunscreen to begin with," Dr. Taylor says. Slather sunscreen on thickly, covering all exposed skin. Pay attention to the areas that usually get missed: ears, around the eyes, neck (all the way around!), hands, feet and toes.
• Use sunscreen or wear long-sleeved clothing when driving, since side-window glass can let in UVA rays as can some windows in buildings. And remember that water, sand, concrete and snow all increase the reflection of sunlight, so put on more sunscreen and shorten your exposure time.