Many Americans still don't use sunscreen, which has been proven to prevent skin cancer, the most common cancer in the U.S.

Sunscreen has been proven to reduce the risk for all types of skin cancer and to prevent or delay signs of aging, but most Americans still don't use it regularly, according to a new study by the federal Centers for Disease Control and Prevention.

The study, published in the Journal of the American Academy of Dermatology, found that only 14 percent of men and 30 percent of women regularly use sunscreen both on their face and other exposed areas. It also showed that more than 40 percent of men and 27 percent of women never use sunscreen on their face or other areas of exposed skin when outdoors for an hour or more, Carrie Myers reports for HealthDay News.

"The overwhelming majority of melanomas -- the deadliest form of skin cancer -- and non-melanoma skin cancers are associated with exposure to ultraviolet radiation from the sun," Dr. Deborah Sarnoff, senior vice president of the Skin Cancer Foundation, told Myers. "That's why daily sun protection is critical," she said.

The foundation recommends that when you are out in the sun you should seek shade, wear protective clothing, including a broad-brimmed hat, wear UV-blocking sunglasses and wear a broad-spectrum daily sunscreen that has an SPF of 30 or higher and is water-resistant,of which you should check the expiration date, Sarnoff told Myers.

The study also found that nearly 40 percent of sunscreen users didn't know whether their sunscreen provided broad-spectrum protection.

"Broad-spectrum means that the sunscreen protects the skin from both UVA and UVB rays. UVB rays are responsible for sunburns, while UVA rays go deeper into the skin, causing sagging and wrinkling. It is believed that both UVA and UVB rays play a role in skin cancer," Myers writes.

"To take advantage of the full protection your sunscreen offers, it should be applied thickly to all exposed skin and reapplied every two hours and after swimming, sweating, and toweling off," Dawn Holman, lead author of the study, told Myers. "Sunscreen is most effective when paired with other forms of sun protection."

Holman recommended products with physical blocks, such as titanium dioxide and zinc oxide, for those who shy away from sunscreens because they fear the chemicals in them. She also told Myers that everyone should avoid midday sun exposure because that is when the UV rays are most intense and encouraged people to check the UV index before going outdoors, saying, "The higher the UV index, the more sun protection you will need."

Skin cancer is the most common cancer in the United States, according to the CDC. The most severe form, melanoma, causes more than 9,000 deaths a year in the United States, Myers reports.

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