Ultraviolet Radiation 

Energy from the sun reaches the earth as broad spectrum of electromagnetic radiation. The earth's atmosphere absorbs one third of the sun's radiation. Of the radiation that reaches the earth's surface 60% is infrared, 37% visible, and 3% Ultraviolet (UV). The UV spectrum composes the 200 to 400 nanometers (nm) wavelength band, and is divided into 3 groups:

• UVA is made up of wavelengths 320 to 400 nm
• UVB 280 to 320 nm
• UVC 200 to 280 nm

• UVB rays are more important in the development of skin cancer than UVA.
• UVA rays cause aging and wrinkling of the skin, but also increase the damaging effects of UVB.

A small amount of sunlight exposure is healthy and assists in Vitamin D formation in the skin. Too much, however, is dangerous and can lead to skin cancer, skin aging and wrinkling, & cataracts.