What Causes Sunburns?

Sunburns are painful burns on the skin that occur shortly after being overexposed to the sun. Sunburns are what most people fear when they go to the beach, and the reason that most people wear sunscreens.

Although most people regard sunburns as a minor annoyance, they can increase risk of skin cancer, and if severe enough, can cause a medical emergency (this occurs most commonly when a person goes on a vacation to a tropical country and underestimates the strength of the sun's rays).

Typical signs of sunburn include:

• Redness of the skin hours after exposure or during exposure if severe
• Warmth on the skin
• A feeling of fatigue and slight dizziness is common
• Skin will peel after several days

Sunburns are caused primarily by the UVB wavelength. Although only about 5% of UVB rays are able to penetrate the ozone layer and reach the earth's surface, they are responsible for the sunburns. Most sunscreens are effective at blocking out most of the UVB rays that hit the skin.

• UVB rays are responsible for causing sunburns. SPF is a measurement of how long the sunscreen will protect the skin against sunburn. Understand, however, that these numbers reflect laboratory conditions, which assume full coverage and no environmental factors like water, wind, or sweat which erodes the strength of the sunscreen.
• Sun avoidance is the best way to protect against sunburn.
• Sunburns, especially those during childhood may increase the risk of some cancers.

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