Sunscreen Facts: Raise Your SPF IQ

July may be the hottest month of the year, but August and early September are chock-a-block with scorchers. As you head to the beach or the bay, are you armed and ready for the wrath of the sun's rays? "Common belief is that SPF 15 will block 95 percent of sunlight," says Charles McDonald, MD, chief of dermatology at Rhode Island Hospital and former president of the American Cancer Society's board of directors. "It does the job under laboratory conditions, but in real life, people just splash it on, thinning it out to an equivalent of SPF 7.

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"The minimum SPF I recommend is 30," McDonald says. "For outdoor activity, use SPF 45 because you'll be perspiring, which dilutes the sunscreen. For those who are very fair, who have red hair, blue eyes and freckles, add a total block that contains titanium or zinc."

If you want to keep your skin supple, shun the sun between 10 a.m. to 2 p.m. when the rays are most intense. Broad-brimmed hats and clothes with a close weave also fend off harmful rays. Keep in mind that sunlight reflected off the bay, the sand—even the concrete of a city sidewalk—is damaging.

If you slip up and stay out too long, take aspirin or a non-steroidal anti-inflammatory drug (NSAID) to counteract redness and pain. Once the sunburn appears, apply cool compresses or mentholated creams.

"People underestimate the damage the sun can do," McDonald warns. "Although rare, malignant melanoma accounts for 50,000 of the one million skin cancer cases diagnosed each year in the U.S." In other words: stay in deep shade and you've got it made.

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