If you're reading this, you probably know that too much unprotected sun exposure can harm your skin, from skin cancer to premature aging. But how exactly does a fiery ball in the sky damage your skin? What is ultraviolet (UV) radiation, and what do you need to know about UVA vs. UVB rays?

Understanding the answers to these questions is the first step in protecting your skin to maintain a healthy, radiant complexion that glows from the inside out.

The Skinny on UV Radiation

UV radiation is one type of natural energy the sun emits. It can also come from artificial sources, like tanning beds, lasers, and some fluorescent lights. UV rays have shorter wavelengths than visible light, so you can't actually see them. Even though it's not visible, your skin can feel UV radiation and be damaged by it, and that damage is cumulative. This means that UV damage adds up over time.

The Difference between UVA and UVB

When it comes to protecting your skin, you need to know about two types of UV radiation: UVA and UVB. Both types can damage your skin, but they have some important differences. Here's the UVA vs. UVB breakdown.

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UVA makes up about 95 percent of all the sun's UV rays that reach the Earth. This is also the main type of radiation used in tanning beds. UVA can go through glass—like your car window—and it penetrates deep into your skin. UVA causes your skin to tan, but according to the American Academy of Dermatology, it also causes premature skin aging. These rays damage your skin's elastin and collagen proteins, causing age spots and wrinkles and generating harmful free radicals. When UVA is combined with UVB, it can lead to even more serious skin concerns, like skin cancer.


UVB only makes up closer to 5 percent of the sun's UV rays. It can't penetrate through window glass or into the deeper layers of your skin, but it's much higher energy than UVA. It mainly affects the top layers of the skin and causes sunburn. But UVB rays also damage your skin's DNA, leading to mutations that can cause melanoma and other skin cancers. UVB rays can also damage your eyes, including cataracts, which can cloud your vision over time.

Considering the UV Index

Different factors affect how strongly UV rays hit the Earth's surface. Avoiding or limiting sun exposure when UV rays are the strongest can help you minimize how much they damage your skin. Here's when UVA and UVB rays are most powerful:

  • In the middle of the day (between 10 a.m. and 4 p.m.)
  • During the spring and summer months
  • In locations closer to the equator
  • In higher elevations
  • Around reflective surfaces like snow, water, and sand

If you're not sure about the UV rays in your area, the US Environmental Protection Agency UV Index can help. Just plug in your zip code to find out how strong the UV rays are where you live on any given day.

How to Protect Yourself from UVA and UVB Rays

You can protect your skin from harmful UV rays in a few ways while you enjoy the outdoors. Topping the list is daily sunscreen use. A sunscreen's SPF (or sun protection factor) describes how well it blocks UVB rays. When choosing a sunscreen, find one with an SPF of at least 30 with "broad spectrum" on the label. This means it also blocks UVA rays. No matter how high the SPF, if it's not broad spectrum, it doesn't protect your skin from UVA.

To check these sun protection best practices off your list, try a sunscreen like EltaMD UV Clear Broad-Spectrum SPF 46. Its lightweight formula goes on smooth, and it contains Niacinamide and Hyaluronic Acid to reduce redness and restore dry, damaged skin.

And remember your lips, which can also be damaged by chronic exposure to UV rays. Nourish them with an SPF lip balm like EltaMD UV Lip Balm Broad-Spectrum SPF 36. This creamy, transparent balm protects against aging free radicals and offers long-lasting moisture.

Raising a Glass to Skin Health

Keeping your skin healthy isn't just about sunscreen. It's also important to seek shade—especially during peak UV hours—and wear a wide-brimmed hat and sun-protective clothing. Incorporate all these sun-protection strategies into your daily routine to keep your skin looking and feeling its best while you have fun under the sun.



    Maria Robinson, MD, MBA is a board-certified dermatologist and dermatopathologist with over ten years of clinical experience. Dr. Robinson has a passion for nutrition and integrative dermatology, and is the co-founder of www.integrativederm.org, where people can explore holistic dermatology treatments. Through her writing, she strives to empower people with accurate health information so they can make positive decisions that lead to healthy and vibrant skin.