Chicago residents have a false sense of security about sun exposure since their gray weather seems to go on forever. But ultraviolet light still shines through the clouds, and it’s impossible to turn back the clock after years of too much sun. “By the time you get a basal cell, the horse is out of the barn,” says Yoo. Here are some tips to help prevent skin cancers:

• Gob on the sunscreen. “No one’s putting it on thick enough,” says Yoo. Apply two tablespoons at least 20 minutes before going outside—and reapply every two hours or after swimming or sweating. Look for a sun protection factor (SPF) of at least 15 and protection against ultraviolet A and B rays.

• Wear a hat with a four-inch brim. It sounds like overkill—and doctors are most likely to do it. “That’s how you can tell the dermatologists,” says June Robinson, a professor of clinical dermatology at the Feinberg School of Medicine and the editor of Archives of Dermatology.

• Get screened. The Skin Cancer Foundation will conduct free screenings in the Chicago area from June 2nd to 4th. Learn more at skincancer.org/Tour.

• Use self-tanners. “The trick to getting people to cease indoor tanning is to give them the look they want,” Robinson says. “Appearance is what it’s all about.”

• Avoid tanning parlors. According to Robinson, 25 to 40 percent of women from ages 18 to 22 visit tanning salons. “The body remembers all of that ultraviolet radiation, from childhood on up,” she says. Instead of focusing exclusively on the risk of cancer, Robinson also warns young people about wrinkles. “A 16-year-old doesn’t care about skin cancer,” she says, “but wrinkles she cares about.” As Robinson reported last May in Archives of Dermatology, education about the negative impact of tanning on skin’s appearance caused a 35 percent drop in indoor tanning visits.