The sun produces energy in the form of light waves.  These light waves are comprised of different lengths and intensity.  The sunlight we see is called visible light.  Ultraviolet radiation is located just above visible light.  Overexposure to ultraviolet radiation from the sun causes sunburn, skin cancer, premature aging (skin wrinkling), cataracts, and DNA damage.

Ultraviolet radiation is divided into different energy levels.  From longest to shortest wavelengths they are UVA, UVB, and UVC.

UVA Rays

UVA rays, while having less energy, penetrate deepest into the skin.  They are the primary cause of premature aging.  UVA rays damage collagen and elastin in the skin, resulting in fine lines, wrinkles, sagging, age spots, broken capillaries and uneven skin tone.  It is the least associated with skin cancer, but if delivered in high doses it can cause skin cancer and other sun-induced skin disorders. 

The ozone layer is the protective layer of the atmosphere, or shield, surrounding the earth.  Because UVA rays pass effortlessly through the ozone layer, they make up the majority of our sun exposure.  UVA rays are also the primary type of radiation emitted by tanning beds.  Contrary to what some people believe, a UVA tan does not protect the skin from further sun damage.

UVB Rays

UVB rays are the most potent rays that reach the earth.   They cause sunburn and can lead to the development of skin cancers.  UVB rays are also responsible for cataracts in the eye (clouding of the eye lens) and immune system damage.

Most UVB rays are absorbed by the ozone layer, but enough of these rays pass through to cause serious damage. 

UVC Rays

UVC rays are the most dangerous, however, these rays are blocked by the ozone layer and don’t reach the earth.

• Ultraviolet rays are invisible to the naked eye.
• Harmful UV rays are more intense in the summer.  Not only is the sun stronger, but skin exposure usually increases since we wear lighter clothing.
• The higher in altitude you are, the thinner the air and the more intense the UV rays. 
• UV rays are also more intense the closer you get to the equator.  For example, Florida receives 150 percent more UV radiation than Maine.
• The harmful effects of UV radiation are magnified by reflective surfaces such as water, snow and sand.  In fact, snow can reflect up to 80% of UV – so watch out skiers!
• UV radiation is present everyday, even if it’s cloudy outside.
• SPF (Sun Protection Factor) ratings mainly measure a sunscreen’s ability to block UVB rays.
• Sunscreen, protective clothing and shelter during mid-day can protect your skin from skin cancer and premature aging.