Sun Damage 101: The Difference Between UVA and UVB Rays

When it comes to the sun's rays, we know one thing for sure: they mean trouble for our skin. Sun damage from UVA and UVB rays can be blamed for everything from the premature signs of aging to skin cancer. But all radiation is not created equal. We share the difference between UVA and UVB rays below.

The sun makes contact with the earth using two different types of harmful rays: ultraviolet A (UVA, or long wave) and ultraviolet B (UVB, or short wave), according to The Skin Cancer Foundation. Neither, of course, is visible to the naked eye—but they’ve both proven to be major culprits of skin cancer, eye damage, a diminished immune system, and the increased appearance of aging—think: wrinkles, fine lines, and dark spots.  

The key difference between the two? UVA rays tend to penetrate deep into the skin, causing an immediate tanning effect and often leading to signs of aging down the line. UVB rays cause surface-level damage, quickly burning and gradually tanning the skin, according to The World Health Organization. And while most UVB rays are filtered by the atmosphere, they are the rays that can cause skin cancer.

There’s also a third type of radiation that is stronger still: UVC rays. Luckily, UVCs are not paid quite as much lip service as they do not typically penetrate the ozone layer to reach our skin, and thus have not been subject to as much scrutiny, according to The Health Physics Society.

According to The Skin Cancer Foundation, our understanding of UVB and UVA rays is constantly evolving. While we once only thought UVB rays to be truly dangerous, increasing attention is being paid to the possible harmful effects of UVA rays. No matter what, it is important to stay vigilant by always wearing broad spectrum sunscreen and maintaining proper skin care practices as research continues to progress.