1. Sunscreens and sunblocks aren’t the same. Sunscreens contain chemical ingredients that absorb harmful ultraviolet light; sunblocks are formulated with micronized minerals like titanium dioxide that reflect rays. Both offer what’s called broad-spectrum protection from ultraviolet B (UVB) and ultraviolet A (UVA) rays, those responsible for speeding up the aging process. But blocks generally provide more coverage, especially for those with sensitive or fair skin, because they act as a physical barrier against damaging light. To be sure a product is a sunblock (many go by the generic term, sunscreen), look for the words chemical-free or ingredients like titanium dioxide or zinc oxide listed on the label. Two examples: Shiseido Gentle Sun Block Cream SPF 22 and AlbaBotanica Sun Oil Free Natural Mineral Sun Block SPF 18.
2 You can tan while wearing sun protection. No product is foolproof–even sunscreen with a sun protection factor (SPF) of 30 protects against only 97 percent of UVB rays, those most responsible for tanning. “If you tan easily, it would take wearing a brown paper bag to avoid getting any color,” says Vincent DeLeo, M.D., associate professor of dermatology at Columbia University, St. Luke’s-Roosevelt Medical Center in New York City. If you tend to burn, it’s even more important to cover up: Supplement a high-SPF sunscreen with a wide-brimmed hat and protective clothing when outside for long periods.
3 Sunscreens can lose their effectiveness. Though most are formulated to last a few years, the reality is that many factors–particularly heat–can diminish a sunscreen’s potency, reports Darrell Rigel, M.D., associate clinical professor of dermatology at New York University Medical School (this is why storing one in your glove compartment or a humid bathroom isn’t wise). A good rule of thumb: Keep sunscreens in a cool dry place (stashed in a dresser drawer or your beach tote in the front closet), and don’t save them from year to year.
4 Cosmetics with SPF don’t provide enough coverage for the beach. Even if a moisturizer or foundation has a high SPF (dermatologists recommend at least a 15), “it won’t stay on if you sweat or go into the water,” says Patricia Farris, M.D., a dermatologist in New Orleans. Most true sunscreens are formulated to stick to the skin.
5 Waterproof and water-resistant sunscreens need to be reapplied. By definition, a waterproof product provides the same protection after 80 minutes in the water that it did before you took the plunge; a water-resistant product lasts 40 minutes. Thereafter, all bets are off. To be on the safe side, always slather on more after swimming or sweating a lot. (A shot-glassful is the recommended amount to adequately cover yourself from head to toe.)
6 Sunscreens cool off the skin. There’s myth that sunscreen causes the body to overheat–a misconception that weekend athletes cite as an excuse not to use it. But researchers at Oregon State University in Corvallis confirmed the opposite. When students exercised vigorously for 45 minutes in over-90-degree heat wearing an SPF-15 sunscreen, their skin temperature was lower than when they exercised unprotected.
7 Don’t rub–smooth it on. When massaged in vigorously, SPF’s effectiveness decreased by nearly 25 percent in one study. According to Memphis-based biophysicist Robert Sayre, Ph.D., when sunscreens were lightly applied (about six finger-passes), they lived up to the promised protection.
8 Sweatproof formulas don’t feel greasy. Despite the fact that they’re designed to really adhere to the skin, “sport” sunscreens go on light. Two to try: Bain De Soleil Le Sport SPF 30 Sunblock and Banana Boat Action Sport Spray Gel SPF 25. An added benefit: Even if you do get some in your eyes when you’re working up a sweat, it won’t sting.
9 Sunscreens for the face and lips aren’t gimmicks. Products for the face dry faster than those for the body (making them ideal for quick morning application), and–because they don’t contain heavy, pore-clogging oils–are better suited for acne-prone skin. Lip balms with SPF are made with waxes to keep lips covered despite frequent licking.
10 Kids don’t need special creams. Protectionwise, sunscreens marketed to grown-ups and children are the same, says Dr. DeLeo. However, if the extras attached to these products make kids less resistant to using them, there’s little to lose. One that’s fun to apply: Coppertone’s new Kids Color-block SPF 30 goes on purple (making it easier for parents to see any missed spots) and then disappears once it’s absorbed.