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What is UV?

Ultraviolet (or UV for short) light is electromagnetic radiation emanating from the sun, with a shorter wavelength than either that of visible blue or violet light. UV radiation is usually associated with sunburn, premature skin aging, as well as other harmful health hazards, such as skin diseases and cataracts. We should consider ourselves quite fortunate, because our planet is protected by an ozone layer that shields its inhabitants from a large amount of UV radiation. However, the ozone layer cannot totally block all UV radiation coming in and some amount of UV radiation still penetrates the earth s atmosphere. This is even more true now, since, as all of us probably know, the earth s ozone layer has become thinner and thinner over the years and it already has a hole in one part.

Ultraviolet radiation is classified into three groups or bands. These bands are known as UVA, UVB, and UVC.

UVA radiation has the longest wavelength of the three bands and cannot be absorbed by the ozone layer. It passes through the ozone layer and is in part responsible for the health hazards mentioned above. It is also said to generate free radicals and cause skin diseases, like melanoma. Although there has not been any related disorder on record, it is suggested that UVA rays are, for the most part, absorbed by the lens of the human eye.

UVB radiation has a medium-sized wavelength that is absorbed by the ozone layer, although some amount of it is still able to pass through. UVB rays can potentially damage the eyes and are responsible for sunburns, increased melanin production, and some forms of skin cancer. Although no conclusions have been made yet, it has been widely suggested by a lot of scientists and researchers that daily exposure to UVB may cause cataracts in your eye.

Unlike the two previous bands, UVC radiation does not command much attention and is not much of a concern, since all of it is completely absorbed by the ozone layer. No amount of UVC radiation can penetrate the earth s atmosphere. Although this is the case and even though it has the shortest wavelength, UVC is the most dangerous and most potentially damaging among all the types of UV radiation.

The amount of UV radiation that reaches the earth varies, depending on several factors: the time of day (highest levels of UV radiation occur at noon, when the sun is at its highest and strongest); the time of year (highest levels of UV radiation occurs during summertime); latitude (highest levels of UV radiation on the equatorial area because the sun is nearest there); altitude (UV intensity increases as the altitude increases, because the atmosphere thins out as one goes farther away from sea level); weather conditions (cloudy weather or overcast skies can help reduce UV levels); and reflection (some surfaces can reflect UV radiation, even if you are in a shaded area). UV radiation levels are measured by means of a globally set measurement standard, called the UVI or Ultraviolet Index.