Glossary / Lexicon

Ultraviolet (UV) light refers to the radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays.Ultraviolet light is a wavelength that is above violet in the

color spectrum. Ultraviolet light is not visible to the human eye. Ultraviolet light, like visible light, is a kind of electromagnetic radiation. The sun is the source of UV light, but there are also other sources that include electric arcs and black lights. Some libraries use UV light to help readers better see documents. Germicidal UV lamps are also used to kill bacteria, viruses and mold spores.

The area of UV light on the spectrum has three (3) regions. Next to the visible violet light is near ultraviolet light; beside ultraviolet is far ultraviolet light; and next to far ultraviolet is extreme ultraviolet light, which is next to the area of X-rays.

UV light can be beneficial, exposure to UV light causes our skin to create Vitamin D, which helps bones absorb calcium. Incidental sun exposure, such as walking to your garden or to the mailbox, for example often provides enough UV light to make the vitamin.

It is hard to determine the amount of UV light that a person can exposed to before damage occurs. The threshold depends on wavelengths of UV of exposure, the amount of exposure and the intensity of exposure.

The extreme and long exposure to UV light has also disadvantges:

Skin exposure to UV light is called sunburn and is a sign of skin damage. The damage ages skin and can also cause cancer; dangerous to the eyes. Symptoms of damage include light sensitivity, a feeling that something is in the eye (especially sand or grit), a pain or burning sensation and tearing. See a physician if you feel any eye discomfort.

Overall, Ultraviolet light can damage health, but it can also maintain or improve health. When ultraviolet light strikes human skin, it triggers the production of vitamin D, which promotes the growth of bones and teeth.