Invisible ultraviolet (UV) light is a part of the electromagnetic spectrum. UV light has shorter wavelengths than visible light and longer wavelengths than X-rays. The short wavelengths mean UV light has energy that can damage living tissues. Unlike X-rays, which go through the skin, ultraviolet light affects only exposed parts of the body, such as the eyes, skin, and hair. According to the UV Foundation, people need some ultraviolet light for vitamin D, but it is wise to limit UV exposure to prevent serious skin problems.
UV Sources
A variety of sources produce ultraviolet light. The Sun is the most important natural UV emitter. Its light contains the UV light that we're most familiar with. Our bodies have evolved to tolerate the Sun's UV for relatively long periods, though excessive exposure will lead to sunburn. Artificial sources of UV light, such as black lights, tanning beds, and germicidal lamps have a wide range of UV intensities, some of which are safe, and some of which are very harmful. Black lights have a safe level of UV light. Germicidal lamps, which are used in hospitals, can cause skin burns and blindness.
Sunburn
When your skin gets an excessive amount of UV, it reacts with a sunburn. This is a short-term, temporary condition that can range from redness to painful peeling and blistering. In severe cases, people experience fever, weakness and occasionally shock. These effects begin about 1 hour after exposure and peak in about 3 days. Peeling skin remains sensitive for weeks.
Wrinkling
According to the University of Maryland Medical Center, long-term exposure to UV light in sunlight ages skin, causing premature wrinkling. Even small amounts of UV light cause reactions in the skin that lead to wrinkles, although, as of 2010, scientists don't fully understand the exact processes involved. They have found that UV light damages the skin's collagen fibers. The body imperfectly heals this damage by forming wrinkles.
Cancers
The University of California, San Diego Medical Center reports that fair-skinned people in sunny climates need to be particularly wary about UV exposure, as it can cause skin cancers. Since tanning spas also use ultraviolet light, you can't consider them to be a completely safe alternative. To help protect yourself, you should use sunscreen when going outdoors.
Hair
UV light weakens the hair, making it more fragile and prone to split ends. It also changes the hair's color. A study in the May 2004 Journal of Photochemistry and Photobiology investigated the effects of UV light on a variety of hair types and found they all lost proteins. It also reported that lighter hair shades changed color more from exposure to UV light than darker hair.
Eye Damage
According to The Ohio State University, various parts of the eye are susceptible to damage by ultraviolet light. UV light may lead to cataracts, a clouding of the eye's lens, and solar retinopathy, which is a temporary loss of vision. Avoid looking at strong UV sources, such as germicidal lamps, as they can damage the retina to the point of blindness.
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