Cancer Care The Difference Between UVA, UVB, and UVC Rays By Adult Congenital Heart Disease Center, July 30, 2014 Warm summer days offer plenty of ways to have fun in the sun, but you may damage unprotected skin in as little as 15 minutes. Shielding your skin from the sun’s ultraviolet (UV) rays is one of the most important things you can do to prevent skin cancer, premature aging, and other types of sun damage. Broad-spectrum sunscreen of at least SPF 30 blocks up to 97 percent of the sun’s rays. You’ll need about one ounce (or a shot glass full) of sunscreen to cover your whole body and face. Reapply every two hours, or more often if you’ll be in the water or sweating heavily. The sun’s rays shine the strongest between the hours of 10 a.m. and 4 p.m., so use extra caution during that time period. RELATED: Sun Damage: The 5 W’s of UV Exposure Learn Your ABCs: UVA, UVB and UVC Rays The sun emits three different types of UV radiation: UVA, UVB, and UVC. All types of UV radiation have the potential to damage your skin, but each type affects your skin differently. UVA rays, which account for 95 percent of radiation that reaches the earth’s surface, cause wrinkles, “sun spots,” and other types of premature aging. They are also strongly linked to skin cancer. UVB rays, which affect skin’s top layer, cause skin cancer and most sunburns. Although UVA and UVB rays pose the greatest risk for sun damage, people who work with welding torches or mercury lamps may be exposed to UVC rays, the most dangerous type of UV radiation. How do you tell the different UV rays apart and how do they affect your skin? Check out the infographic below to “learn your ABCs!” Summer days should be spent enjoying a little bit of sunshine, not worrying about the harmful effects of the sun and UV rays. By arming yourself with sunscreen, protective clothing, and the right sunglasses, you can safely enjoy outdoor activities today without fear of damage to your skin later. If you are concerned about any abnormal moles or skin discolorations as a result of years of unprotected sunbathing, please visit the UPMC Hillman Cancer Center website or call 412-647-2811 to schedule an appointment.