UVA (ultraviolet-A) and UVB (ultraviolet-B) refer to two different wavelengths in the light spectrum. UVA rays are long-wave rays while UVB rays are categorized as short-wave rays. Although UVB is generally more damaging to the skin, both UVA and UVB are responsible for premature aging of the skin, wrinkles and sunburn. Sources of UVA and UVB include not only the sun, but tanning beds.

UVA: The ‘Aging’ Ray

Although less likely than UVB to cause sunburn, UVA penetrates the skin more deeply and can contribute to wrinkles, DNA damage and possibly skin cancer. UVA light is also known as "dark-light" and, due to its longer wavelength, can penetrate most windows, light clothing, and windshields. UVA rays are the same strength all year round. It doesn’t matter how near or far away the sun is from the earth—the ray remains the same strength.

UVB: The ‘Burning’ Ray

UVB is strongest during the summer months. UVB is more potent than UVA in producing a sunburn. When exposed to the sun or other ultraviolet light sources such as tanning beds, the body defends itself by releasing the brown pigment, melanin, to protect the vulnerable skin tissues which lie deeper down. Sunburn results when the amount of exposure to UV exceeds the ability of melanin to protect the skin.

Lotions and creams that partially block UV are widely available. Most of these products contain an SPF (Sun Protection Factor) rating indicating the amount of protection given. This protection, however, applies only to UVB (burning) rays responsible for sunburn and not to UVA (aging) rays that penetrate more deeply into the skin. Good sunscreens contain compounds which help protect against UVA rays. These newer preparations can offer substantial protection against both UVA and UVB.