TranscriptDr. Mayzik Ultraviolet, or UV, radiation is a major cause of skin cancer. Dr. Patel, can you tell us about UV radiation? Dr. Patel Definitely, Dr. Mayzik. Sunlight consists of three types of harmful rays: ultraviolet A, or UVA, ultraviolet B, or UVB, and ultraviolet C, or UVC, rays. UVC rays are filtered out by the ozone layer, but UVA and UVB rays reach the Earth’s surface. UVA rays, which can pass through window glass, penetrate deeper into the dermis, the thickest layer of the skin. UVA rays can cause suppression of the immune system, interfering with its ability to protect against the development and spread of skin cancer. UVA exposure can lead to signs of premature aging of the skin, such as wrinkles or age spots. Because tanning beds use UVA bulbs, tanning bed exposure not only increases the risk for skin cancer, but can also dramatically accelerate the skin aging. UVB rays are the sun's burning rays, which are blocked by window glass, and are the primary cause of sunburn. UVB rays are also the wavelength of light that generates vitamin D in the skin. Since tanning beds use UVA bulbs, they do not help the skin produce vitamin D. Excessive exposure to both forms of UV rays can lead to the development of skin cancer. Therefore, sun-safety strategies, such as limiting sun exposure and applying sunscreens that absorb or block UV rays, are important.