Ultraviolet light is the light emitted from the sun. When you are exposed to too much UV light without proper protection from sunscreen, your skin can burn. Sunburn is an immediate risk from unprotected sun exposure. Long term, though, too much sun exposure can cause skin cancer, premature aging and cataracts. To protect against sunburn and other harmful effects from the sun, use sunscreen every time you are outdoors, even on a cloudy day.
Types of Ultraviolet Light
Three types of ultraviolet light exist in the atmosphere: ultraviolet A, or UVA; ultraviolet B, or UVB; and ultraviolet C, or UVC. Only UVA and UVB light pose health risks, because UVC rays are absorbed by the ozone layer, according to the Environmental Protection Agency. Both UVA and UVB light filter past the ozone layer, although some UVB rays are absorbed before reaching Earth's surface. Because both UVA and UVB light pose health risks, look for sunscreens that protect against both.
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What Is Sunburn?
A sunburn develops when the amount of ultraviolet light--or UVA and UVB rays--you are exposed to is more than your skin pigment, called melanin, can protect against, according to MedLine Plus. The ability of your skin to tolerate sun exposure depends on the amount of melanin in the skin. Fair-skinned people can burn in a matter of minutes, while those with dark skin may be able to spend hours in the sun without burning. However, even people with dark skin who burn infrequently put themselves at risk of the harmful effects of the sun if they do not protect themselves with sunscreen.
Sunscreen Use
Sunscreens and sunblocks protect the skin from damaging UVA and UVB light by reflecting, absorbing and scattering the sun's rays, according to the American Academy of Dermatology. To protect against sunburn and other damaging effects of the sun, you should use sunscreen whenever you will be exposed to sunlight. For it to be effective, it should be applied 15 to 30 minutes before going out into the sun. Reapply it every two hours or after getting wet or sweating heavily.
Sun Protection Factor
All sunscreens are given a sun protection factor--or SPF--which indicates how well it protects against the sun and can prevent sunburn. Sun protection factors can range between 2 and 50, with higher numbers providing greater protection, according to the American Melanoma Foundation. For example, a 2 SPF sunscreen absorbs half of UV radiation, while a 34 SPF absorbs 97 percent. The American Academy of Dermatology recommends using water-resistant sunblock with an SPF of at least 30.
Cloudy Days
You can get sunburned even on a cloudy day. As much as 80 percent of the sun's harmful rays can pass through the clouds and reach Earth's surface, according to the American Academy of Dermatology. That means you have to lather up with sunscreen on a cloudy day just as you would on a sunny day, especially if you are at the beach or skiing or playing in the snow. That's because sand and snow can reflect the rays of the sun back at you, putting you at greater risk of sunburn. Snow is particularly reflective, reflecting 80 percent of sunlight. Sand reflects 25 percent.
Posted in: Skin Care