• Is an invisible form of light and energy given off primarily by the sun
• Can penetrate the upper layers of our skin
• Is absorbed by DNA and can change its structure (causing mutations)
• Some DNA changes can be corrected--if not, changes can lead to unchecked cell growth (ie, cancer)
• If you are exposed to frequent and intense UV radiation, you are exposed to one of the major risk factors for melanoma.

There are 3 types of UV rays:  

• UVA (Long wavelength)

                       -  Penetrate deeply

                       -  Associated with wrinkling / leathering of skin

                       -  Makes UVB-induced damage worse

                       -  Directly stimulates skin cancers

• UVB (Medium wavelength)

                       -  Burning waves

                       -  Primary cause of sunburn

                       -  Main cause of basal cell and squamous cell carcinoma as well as cause 

                          of melanoma

• UVC (Short wavelength)

                       -  Absorbed by ozone layer

                       -  Not thought to induce skin cancer

Although both UVA and UVB can cause damage, the skin reacts differently to each one.

Comparison of UVA and UVB