Whether one is driving down to Rocky Point, skiing on Mount Lemmon, or just hanging out by the pool, exposure to the sun's ultraviolet rays can cause damage to the skin.

"There is no such thing as a safe tan," said Paola Werstler, health educator for the Arizona Cancer Center. "To lie out just to get color defeats the whole purpose. It's the skin's way of saying that it's damaged."

When UV rays enter the skin, protective melanin is brought out, causing the skin to become darker, said Laurie Weymann, nurse practitioner at the Student Health Center. "We need to get people away from the thought that they have to have milk chocolate skin to be attractive."

Clouds and cold weather do not screen out the UV rays, said Weymann. Ice and snow reflect the UV light, and this reflection is many times more harmful to the skin than direct exposure. Eighty percent of the UV rays penetrate clouds on overcast days.

"The closer you are to the sun, the higher altitude you go, and the closer you are to the equator, the more direct UV light you get hitting you," Weymann said.

Sunscreens are classified by their Sun Protection Factor (SPF). The SPF numbers are listed on the packaging and range from 2 to 50. The number reflects the amount of time skin is protected and the amount of UV light skin is protected from. Werstler suggests wearing a minimum sunscreen of SPF 15. "SPF 15 blocks out about 96% of the UV light," she said.

Werstler said to use the "times ten" rule when applying sunscreen. If you multiply the SPF by 10, it equals the amount of time you are protected by the sunscreen. For example, a sunscreen of an SPF of 15 will protect you for about 150 minutes.

"Any sunscreen with an SPF higher than 15 takes that much longer to sweat off," said Weymann.

One good ingredient to look for when buying sunscreen is titanium dioxide, said Werstler. It is in the same family as zinc oxide, but its molecular structure is smaller, allowing it to soak into the skin.

Find something you like the smell and feel of, and that you can afford, said Weymann. "If you don't wear it, it isn't going to protect you."

Too much exposure to the sun's UV rays increases risk of skin cancer. This is a malignant condition caused by uncontrolled growth of cells in one of the layers of the skin. There are three types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma, which can be deadly.

If detected early, most cancers can be successfully treated and often cured, according to the Arizona Cancer Center.

"By the age of 18, most people have 80 percent of their permanent skin damage, so after that, they have very little to work with," Werstler said. "Early detection is paramount."

More than three blistering burns before the age of 20 increases the risk of melanoma, the most dangerous type of skin cancer, said Weymann.

Most skin cancer does not show up for 10 years, said Werstler.

"Because there is no immediate risk, most people think it's no big deal. It is a long-term commitment to your health. It's not worth risking your life over."