Sunburns are caused by exposure to too much ultraviolet (UV) light. UV radiation is a wavelength of sunlight in a range too short for the human eye to see. Ultraviolet A (UVA) and ultraviolet B (UVB) are the two types of solar radiation most responsible for sunburn. Sunlamps and tanning beds also produce UV light and can cause sunburn.

Melanin is the dark pigment in the outer layer of skin (epidermis) that gives your skin its normal color. When you're exposed to UV light, your body protects itself by accelerating the production of melanin. The extra melanin creates the darker color of a tan.

A suntan is your body's way of blocking the UV rays to prevent sunburn and other skin damage. But the protection only goes so far. The amount of melanin you produce is determined genetically. Many people simply don't produce enough melanin to protect the skin well. Eventually, UV light causes the skin to burn, bringing pain, redness and swelling.

You can get sunburn on cool, hazy or cloudy days. As much as 80 percent of UV rays pass through clouds. Snow, ice, sand, water and other surfaces can reflect UV rays, burning your skin as severely as direct sunlight.

May 01, 2014