Skin Care Related Terms that begin with the letter U

ultraviolet – electromagnetic rays beyond the violet end of the visible spectrum. The range of invisible radiation wavelengths from around 4 nanometers to 380 nanometers. Often called UV radiation and comes naturally from the sun. Divided into 3 categories based on wavelength.

UVA – (320 to 400 namometer wavelength) not readily affected by ozone levels. Most of these waves reach the earth and contribute to skin aging and eye damage.

UVB – (280 to 320 namometer wavelength) readily affected by ozone levels. Decreases in ozone levels lead to increase UVB radiation reaching the earth. Increased UVB leads to a variety of skin problems including sunburn, skin cancer and premature aging.

UVC – (100 to 280 nanometer wavelength) very readily affected by ozone levels. Very little UVC radiation reaches the earth’s surface.

UV - ultraviolet

UV Index – a measure of the intensity of the sun’s ultraviolet radiation in the sunburning spectrum (290 to 400 nm). As the UV Index increases, the sun’s rays can do more harm to your skin, eyes and immune system and one should therefore take more precautions to protect yourself from the harmful rays. In Canada, the UV Index ranges from 0 – 10. 0 – 4 is low, 4 to 7 is moderate, 7 – 9 is high, and over 9 is extreme. For more information on how the UV Index is calculated in the U.S. click on this link - http://www.epa.gov/sunwise/uvcalc.html