Newsletter XIX - Reflected UV Protection
It's true: shade is an excellent tool for UV protection. But it's important to understand that finding complete protection is not always as simple as sitting in the shadow of a tree or a beach umbrella. UV is reflected by many surfaces. While direct UV rays travel in a straight line from the sun, indirect UV radiation can come from any direction.
Many people know that when they're at the beach, surf and sand can reflect significant amounts of UV rays. But few realize that indirect UV radiation is reflected off of buildings-particularly those painted white-and off of light-colored concrete surfaces, such as sidewalks, patios, and driveways. Ultraviolet rays bounce, so while you're sitting beneath a tree near a lake or under an umbrella on a beautiful pool deck, you still may be exposed to enough indirect UV radiation to get sunburned. It will take longer to get burned than if you are directly exposed, but the consequences will be the same.
Knowing which surfaces reflect UV rays will help you better assess the level of indirect UV radiation you might be exposed to, even in the shade. A 1986 study by U.S. Army scientist David Sliney listed common materials and the level of UVB they reflect:
- Fresh snow - 88 percent
- Sea surf - 25 to 30 percent
- White paint - 22 percent
- Dry beach sand - 15 to 18 percent
- Light-colored concrete - 8 to 12 percent
- Asphalt - 4 to 9 percent
- Open water - 3 to 8 percent
- Grass - 2 to 5 percent
When you're out and about this summer, don't rely on shade alone to shield you from UV radiation. Use trees and shade structures to help block the sun's direct rays, but keep in mind that indirect rays are reflected by surrounding surfaces. For optimal UV protection against reflected UV, apply broad-spectrum sunscreen to your face, neck, hands and feet; wear UV sunglasses; and cover up with sun protective clothing or swimwear.
Summertime is precious. And so is your skin.