Ultraviolet Light


Ultraviolet light is divided into 3 bands or wavelength ranges, which are referred to as UVA, UVB and UVC.

UVA, known as the tanning ray, is primarily repsonsible for darkening the pigment in our skin. UVA is less energetic than UVB, so exposure to UVA will not result in a burn, unless the skin is photo-sensitized or excessive doses are used. UVA penetrates more deeply into the skin than UVB due to its' lower wavelength. Most tanning bulbs have a high UVA output, with a small percentage of UVB.

UVB,sometimes called the "burning ray" is the primary cause of sunburn when we are overexposed to sunlight. However, UVB also initiates beneficial responses, such as stimulating the production of Vitamin D3, which is necessary to help our bodies absorb calcium and which also helps to repair damaged skin cells. UVB also stimulates special skin cells called melancoytes to produce melanin, which becomes additional protective pigment. Therefore, UVB in careful doses increases our pigmentation and so increases the sun protection factor (SPF) of our skin. UVB does not penetrate very deeply into the skin. The darker or more tanned the skin, the less UVB penetrates.

UVC is the most energetic of the UV bands and will burn human skin in extremely small doses over short periods. However, it is completely blocked by the ozone layer.