What is UV Radiation?

The sun generates a spectrum of rays, including UV (or ultraviolet) radiation, visible light and infrared waves. The differences in the sun's rays are related to the length of the wave (or wavelength):

• Humans and most other animals use visible light to see.
• Infrared waves are long. They produce heat.
• Ultraviolet waves are shorter than visible light waves. Some birds can see in the UV range.

UV radiation is broken down further into UVA, UVB, and UVC rays:

• UVA is not absorbed by the ozone layer. It makes up most of the UV radiation that reaches the Earth's surface. It may contribute to skin cancer, sunburn, cataracts, immune suppression, and photoaging.
• Much UVB is absorbed by the ozone layer. It is thought to cause skin cancer, sunburn, cataracts and immune suppression. The SPF sunscreen ratings measure only protection against UVB radiation.
• UVC is the most damaging type of UV ray. Fortunately, the sun's UVC rays are completely absorbed in the atmosphere and do not reach people on Earth. However, some solar lights and tanning beds produce UVC radiation.

Ozone and UVB Rays

The Earth's ozone layer absorbs most, but not all, of the sun's UVB rays. More UVB radiation is reaching the Earth's surface, because manmade chemicals are thinning the ozone layer. As a result, skin cancers may become even more common.

Other Factors Affecting UV Levels

UV rays are 4-5% stronger for each 1000-foot increase in elevation. Also, UV rays get stronger closer to the equator. For example, UV rays are stronger in Florida and Mexico than in Maine and Canada.

UV Index

The UV Index was developed by the National Weather Service and the Environmental Protection Agency (EPA). The UV Index predicts the level (from 0 to 10+) of UV rays during the noon hour each day. The UV Index is available for any ZIP code in the United States and Puerto Rico.

Check your local newspaper, TV or radio weather forecast each day for your area's UV Index. You can also check several websites: EPA, Weather Channel and National Oceanic and Atmospheric Administration (NOAA).

If the UV Index for your area is 5 or above:

• Use extra sun protection measures when children are outside.
• Have children play in the shade.
• Schedule outdoor activities for early morning and late afternoon.
• Use sunscreen and sun-protective clothing.