UV Radiation 101

What Is UV Radiation?

The media has focused a lot on sun damage in recent years. On the news, they say that soaking up too much sun can cause cancer. Commercials for beauty products extol the virtues of creams and lotions that claim to reverse the signs of sun damage. Articles in magazines also link wrinkles and age spots to sun exposure. And while these messages may be grounded in scientific study, a lot them don't explain why UV radiation gets a bad rap or how the rays actually work.

To understand UV radiation, you have to look into the light, or more specifically, the spectrum. The electromagnetic spectrum consists of several types of electromagnetic radiation -- basically streams of photons (little bundles of energy or light) -- traveling in waves. This spectrum includes everything from radio waves to the visible light that we can see, and it ranks the various waves according to the degree of energy they emit and their wavelength. UV rays fall at the high energy/short wavelength end of the spectrum -- making them one of the more dangerous forms of radiation [source: NASA, Zeman].

There are two types of UV radiation that penetrate our atmosphere -- UVA and UVB radiation. UVA radiation is a longer wave than UVB radiation. People need UVA and UVB radiation to synthesize vitamin D; so essentially, you need sunlight to stay healthy. But too much exposure to UVA radiation can darken and toughen the skin. UVB radiation is more dangerous. Some UVB rays are captured by the ozone layer, but those that get through can cause photochemical changes to skin cell DNA; these changes manifest themselves as sunburns and skin cancer [source: Zeman].

Researchers once thought that UVA rays were "safe" compared to UVB rays. This was an understandable assumption to make, since UVB radiation is responsible for the most obvious damage to the surface of the skin, including many forms of skin cancer. But studies have shown that there is no truly safe form of UV radiation. UVA radiation, in addition to causing wrinkles, also causes permanent damage that can, in fact, lead to some types of skin cancer [source: American Cancer Society].

Since exposure to any UV rays can clearly lead to cancer, it's useful to know which skin growths you should remove and which ones do not spread. Read on to find out.