Sun protection quiz: Can sunscreen alone prevent sun damage?

Sunscreen absorbs, reflects or scatters ultraviolet light — invisible rays of the sun that can cause sunburn and other skin damage. Though it offers some protection, it doesn't block out all of the ultraviolet rays. Therefore, sunscreen shouldn't replace other protective measures, such as limiting the time you spend in the sun and covering your skin. For the most complete sun protection, use all three of these methods:

• Avoid the sun between 10 a.m. to 4 p.m., when the sun's rays are the most damaging.
• Wear protective clothing, long-sleeved shirts, long pants and wide-brimmed hats.
• Apply sunscreen liberally 30 minutes before going outdoors and reapply according to the directions on the label — usually about every hour.

Ultraviolet rays bounce off snow, ice, sand, water and other highly reflective surfaces and can burn your skin as severely as direct sunlight can. So, for example, a wide-brimmed hat may shield your head from the sunshine, but it won't protect your face and neck from the ultraviolet rays that reflect off the sand or water.

As much as 90 percent of ultraviolet rays can pass through clouds, so you need to protect your skin any time you're outdoors.

Darker clothing absorbs ultraviolet rays and provides better protection than white or light-colored clothing does. In addition, dry clothing is better than wet clothing, which sticks to your skin and allows ultraviolet rays to pass through.

Another factor to consider is the weave of the fabric. Tightly woven fabrics, such as denim, offer greater sun protection than loosely woven fabrics, such as knits. If you aren't sure of the weave, hold the garment up to a light or window to see how much light goes through the fabric. The less light you see, the more protective the fabric.

Make sure your sunscreen has an SPF of at least 15. SPF ratings indicate how much longer you may be protected from sunburn than you would be if no sunscreen were applied. For instance, if you normally burn in 20 minutes, a product with SPF 15 will, in theory, allow you to stay out in the sun 15 times as long — or about five hours. But many factors, such as humidity, sweat, friction and water, can reduce how long the sunscreen offers protection. Plus the protective factor of the sunscreen breaks down with passing of time. So don't rely on the SPF factor to decide how long you're safe in the sun.

The shade of the lens doesn't tell you whether it protects your eyes from the sun's rays. In fact, you won't be able to see any difference between lenses that block the ultraviolet rays and those that don't. Look for a manufacturer's label that says the sunglasses block 99 percent or 100 percent of all ultraviolet light. To be even more effective, choose sunglasses that fit close to your face or have wraparound frames that block sunlight from all angles.

You may think that sunbathing once in a while is OK, but intermittent and intense sun exposure may increase your risk of melanoma — the most serious and most deadly type of skin cancer.

Anyone can develop skin cancer, even those with darker pigmented skin. For this reason, the American Academy of Dermatology recommends that all people take precautions against sun exposure, regardless of their skin type or color.