Which is exactly the wrong thing to do.

"We live in Florida," says Dr. Brian Harris, a Fort Myers dermatologist who specializes in skin cancer. "We need the most protection from the sun we can get."

According to the American Cancer Society, most of the more than one million cases of
nonmelanoma skin cancer diagnosed yearly in the United States are sun-related. Melanoma, the most serious type of skin cancer, accounted for about 59,600 cases of skin cancer in 2005 and about 7,800 of the 10,600 deaths.

And the news for Floridians is especially concerning. Age-adjusted incidence rates for melanoma in Florida increased from 1981 to 2001. The Florida Department of Health says that more than 3,000 new melanoma cases are reported each year to the statewide cancer registry, the Florida Cancer Data System. One bit of encouraging news is that the age-adjusted mortality rates for melanoma declined from 1991 to 2001.

So what exactly should Floridians be doing to keep their chances of skin cancer—both melanoma and nonmelanoma—down? We asked Harris and Dr. Craig Eichler, a Naples dermatologist specializing in skin cancer, for their best professional advice.

First, opt for the higher sun block. Don’t leave the house with less than a 30 SPF on. Most basal cell and squamous cell skin cancers—the nonmelanomas—are caused by ultra-violet radiation produced by the sun. Several years ago, the media jumped on a study that suggested there really wasn’t much difference between wearing a 15 SPF, which gives 92 percent protection from the sun, versus the 97 percent found in a 30 SPF. Eichler says there is another, more realistic, way of looking at those numbers.

"Would you like 8 percent radiation exposure or 4 percent radiation exposure?" He asks rhetorically. "The light down here is strong—the higher SPF is more beneficial."

Most people also make the mistake of not putting the block on thick enough or far enough in advance. Harris and Eichler said block should be put on 30 minutes prior to going out into the sun to allow the skin to absorb the lotion. And at least a teaspoon has to be applied to the face and neck. About one ounce—or a shot glass full—should be applied to the whole body.

"A tan is a response to damage from ultra-violet rays," Eichler says. "So you don’t even have to get a burn for your skin to be damaged by the sun. Cellular damage doesn’t take long."

Harris advises Floridians not to fool themselves into thinking that because they’re using sunblock, they can stay out in the sun longer. Staying out longer because you’re using sunblock just means you’ll end up getting the same amount of UV light as you would otherwise. And there is no such thing as "sweat-proof" or "waterproof" sunblock. Eichler agrees. "If you are going to be sweating heavily you have to reapply every two hours," he says. "And if you’ve been in the water, reapply it immediately."

Look for sunblocks that are a broadband—they protect against both UVA and UVB rays. Ingredients to look for are zinc oxide, parasol 1789, avobenzene and a newly patented ingredient, Mexoryl. The Food and Drug Administration approved the new sunscreen agent in August, the first new sunscreen filter since 1988. Mexoryl offers protection against the short UVA waves. The ingredient can be found only in L’Oréal products.

Clothing is another
important layer of protection against the sun. Both Harris and Eichler suggested wide-brimmed hats—at least two to three inches the entire way around—and long-sleeved shirts and pants. Some lines of clothing have been developed with UV protective materials. Sunglasses are also important for protecting the delicate skin around the eyes.

The best course of action, of course, is to stay out of the sun during the peak hours of the day. What those are depend on the time of year, Eichler and Harris say. In the summer, when the sun is at its strongest, you probably don’t want to be in direct sun from 10 a.m. to 5 p.m. But in the winter months, when the sun sets around 5:30 p.m., that time is more likely to be 3 p.m. If you have to be out during the peak hours, seek shaded areas.

"I tell people to use the shadow rule," Eichler says. "If your shadow is as long as or longer than you, it’s safer to be in the sun with protection on. When your shadow is shorter than you, you are better to be indoors."

When it comes to protecting skin, the younger the lesson is learned, the better. Preventing overexposure to the sun’s UV rays is especially important for children and teens because nearly 80 percent of the average person’s lifetime exposure happens before age 18, according to the American Cancer Society. And cancer researchers believe childhood sunburns may increase a person’s risk of developing melanoma.

Harris learned this lesson first-hand. Although he had never had melanoma, he has had several basal cells removed over the years.

"I did a lot of windsurfing and going to the beach when I was young," he says. "And I wasn’t as careful as I should have been. So over the years, I’ve had to have some cancers cut off me."

Getting the message through to younger people is the key to preventing skin cancer, both doctors say. Seniors and adults tend to be more cautious with the sun. But even then, it’s hard for them to understand most of the damage was done long ago.

"If you tell an ex-smoker they have lung cancer, they will often say, ‘Well, I did smoke for 20 years,’" Harris says. "It’s easier for them to understand. But when it comes to skin cancer, it’s hard to understand it was something you did 40 years ago [that caused it]."