UVA and UVB Rays

What's the Difference Between UVA and UVB Rays?

Women laughing together on boat
Blend Images - Colin Anderson/Brand X Pictures/Getty Images

The sun produces two kinds of rays — UVA and UVB rays — which cause damage to our skin. Since the sun's rays can cause everything from skin aging to skin cancer, there are many reasons to protect yourself from the sun. But before you think that since you apply sunscreen regularly you're in the clear, knowing the difference between UVA and UVB rays can help you pick out the best sunscreen for you. In addition, it is 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. If you think you can't get sun damage on a cloudy day, tell that to the UVA rays. They are so powerful that they also penetrate clothing and even glass. (When was the last time you applied sunscreen before getting behind the wheel?)

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 we now know that using tanning beds before the age of 30 can actually increase your risk of skin cancer by 75 percent!

Also UVA rays are responsible for skin aging because they are able to penetrate much deeper into the surface of the skin, damaging the skin cells beneath. While people think their skin looks younger and even healthier when it's tan, the reality is that each tan is creating irreversible skin damage. Many times this skin damage does not show up immediately but rather 10, even 20 years later.

Your skin will have wrinkles, dark spots, and an 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 blame when you get a sunburn. Unlike UVA rays, these rays aren't always the same strength year round; they are stronger in the summer months.

However, UVB rays reflect off of water or snow and cause a sunburn even in the winter, so it's always important to protect yourself year-round with sunscreen.

UVB rays are responsible for causing most skin cancers. While large doses of UVA rays can contribute to cancer, it's the UVB rays that are commonly to blame. If you've heard the advice to stay out of the sun though the mid day hours, it's the UVB rays you're trying to avoid. They are most prevalent mid day, so if you must 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 sunscreen started including UVA protection.  Look for one that specifically says UVA/UVB or "broad spectrum coverage" on the bottle. Do not buy a sunscreen for you or your family that does not provide protection from both types of rays. Be sure to use a sunscreen with a minimum of SPF 15 and reapply every hour or two. Apply your sunscreen generously! Almost no one applies enough sunscreen. You should be using approximately a full ounce on your body (a shot glass size of sunscreen) and about 1 teaspoon on your face each time you apply.

Keep in mind how to figure out how much protection your sunscreen is giving you from the sun. For example, if you are using a sunscreen with SPF 15 and your unprotected skin burns after 20 minutes in the sun you can stay outdoors 15 times longer or about 5 hours. That is, of course, if you applied enough sunscreen to begin with. Don't forget to protect the tops of your ears, neck, chest, hands, and feet.

Lastly, don't let the weather decide for you if you are going to apply sunscreen or not. Even if it is a cloudy or rainy day, be sure to protect your skin from the sun's damaging rays. The less you protect your skin, the more prone you are to sunburn, cancer and skin aging.

Updated by Hanah Tetro