UVA and UVB Rays: The Difference

Updated 05/13/19
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The sun produces two kinds of rays—UVA and UVB rays—both of which cause damage to our skin. Since the sun's rays can cause everything from skin aging to skin cancer, there are plenty of reasons to protect yourself from the sun. But before you think that applying sunscreen regularly means you're in the clear, you should know the difference between UVA and UVB rays, and pick out the best sunscreen for you. When you're purchasing a product, you want to know what you're getting, so it's important to know just what each ray is responsible for when it comes to damage to our skin.

UVA Rays

UVA rays are constantly present, no matter the season or the weather. This is why you're told to wear sunscreen all the time, not just when it's sunny out. It could be stormy, but UVA rays still come through. They're so powerful that they penetrate clothing, or even glass. So, when was the last time you applied sunscreen before getting behind the wheel of a car?

The thing is, UVA rays used to be considered relatively safe, and that's why tanning beds, which use UVA rays, advertise themselves as a safe way to get a tan. But now, we know that using tanning beds prior to the age of 30 can actually increase your risk of skin cancer by 75 percent.

Turns out, UVA rays are what's responsible for skin aging, because they're able to penetrate much deeper into the surface of the skin, damaging the skin cells beneath. While people think their skin looks younger and healthier when it's tan, the reality is that each tan creates irreversible skin damage. Many times this skin damage doesn't show up immediately but 10, 20 years later. Your skin could have wrinkles, dark spots, or develop a bumpy texture.

Bottom line:  When you think of UVA rays, remember they are causing sun spots, leathery skin, and wrinkles.

UVB Rays

UVB Rays are the rays you can resent for giving you sunburns. Unlike UVA rays, these rays aren't always the same strength year round; they are stronger in the summer months. However, UVB rays can reflect off of water or snow and cause a sunburn even in the winter, so it's still important to protect yourself year-round with sunscreen.

UVB rays are also responsible for causing most skin cancers, which is why they're the ones people tell you to watch out for. While large doses of UVA rays can contribute to cancer, it's the UVB rays that are usually to blame. You've definitely heard the advice to stay out of the sun though the mid day hours—it's the UVB rays you're trying to avoid by doing that. They're most prevalent mid-day, so if you have to be out at that time, protect your skin with clothing, a wide brimmed hat, and of course sunscreen.

Bottom line: When you think of UVB rays, think sunburn and cancer.

How to Protect Your Skin

All sunscreens protect against UVB rays, but it wasn't until recent years that sunscreens started including UVA protection.  Look for one that specifically says UVA/UVB or "broad spectrum coverage" on the bottle. Don't buy a sunscreen that doesn't provide protection from both types of rays. At minimum, it should be SPF 15, and you should reapply every hour or two while you're in the sun. Apply generously, because almost no one applies enough sunscreen. You should be using approximately a full ounce for your body (a shot glass size of sunscreen), and about 1 teaspoon on your face, each time you apply.Don't forget to protect the tops of your ears, neck, chest, hands, and feet.

Also, figure out how much protection your sunscreen is giving you from the sun. If you're using a sunscreen with SPF 15, and your unprotected skin burns after 20 minutes in the sun, you can stay outdoors 15 times longer—about 5 hours. 

Don't let the weather decide for you on whether you're going to use sunscreen. Even if it's a cloudy or rainy day, protect your skin. The less you protect it, the more prone you are to things no one wants, like sunburn, cancer and skin aging.

Updated by Carolyn Hanson

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