Are All UV Light Frequencies Dangerous?

One of the most harmful things to humans is all around us, but we cannot see it: ultraviolet (UV) light. Our sun releases almost all of earth's natural UV light, but how much exposure the average human receives depends on environmental factors. Even the weakest of UV light can cause detrimental, even deadly consequences. However, UV does have a few beneficial uses.

Identification

• UV light is a high frequency part of the light spectrum that is not visible to the human eye. Scientists further divide UV light into three categories of increasing energy: UVA, UVB and UVC. The sun emits most of the UV light found on our planet, but our atmosphere absorbs 97 to 99 percent of the most dangerous frequencies, according to NASA (National Aeronautics and Space Administration).

Factors

• How much UV humans are exposed to depends on three main factors: location, cloud cover and industrial closeness. The higher and closer to the equator you are, the more exposure to UV rays you experience. NASA reports that the poles receive a thousand time less UV rays than the equator. Cloud cover acts as a natural shelter from UV rays. Finally, industrial pollution forms ozone, which absorbs UV light.

Is All UV Light Dangerous?

• Even UVA, the least energetic and dangerous of the UV spectrum can still cause some of the effects seen in higher frequency UV light, according to the Textbook of Cosmetic Dermatology. For quite some time scientists believed that UVA was harmless because it does not cause sunburn like UVB and UVC. Because UVA does not show signs of damage, it can accumulate much easier and cause aging, DNA damage and lesions.

Function

• The high frequency and energy of UV light leads to its harmful interactions with the human body. Although the body has mechanisms to absorb UV light safely and fix any DNA damage, the body is not perfect and some damage is irreparable. One of the side effects of broken DNA is an increased risk of skin cancer. Even the eye, which deals with UV light much better than skin, can develop cataracts from too many UV rays.

Benefits

• Despite the potential to damage the skin and eyes, UV light does have some beneficial uses. The body produces vitamin D when UV comes in contact with the skin. The highest energy, UVC light, can kill bacteria and sterilize medical equipment. In astronomy, UV light is essential for studying some of the super-hot objects in the universe, according to NASA.