What Are Sunscreens?
Sunscreens are products combining several ingredients that help prevent the sun's ultraviolet (UV) radiation from reaching the skin. Two types of ultraviolet radiation, UVA and UVB, damage the skin and increase your risk of skin cancer. Sunscreens vary in their ability to protect against UVA and UVB.
What Are UVA and UVB?
Ultraviolet (UV) radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye. Ultraviolet A (UVA) is the longer wave UV ray that causes lasting skin damage, skin aging, and can cause skin cancer. Ultraviolet B (UVB) is the shorter wave UV ray that causes sunburns, skin damage, and can cause skin cancer.
What Is SPF?
SPF – or Sun Protection Factor – is a measure of a sunscreen's ability to prevent UVB from damaging the skin. Here's how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer – about five hours. Most sunscreens with an SPF of 15 or higher do an excellent job of protecting against UVB.
What Does Broad-Spectrum Mean?
Broad-spectrum sunscreens protect the skin from both UVA and UVB rays.