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What's The Difference Between UVA and UVB Rays?

The sun emits UVA and UVB radiation, each of which affects the skin differently. Here, learn how UVA and UVB rays differ and how to protect against both.

Many consider SPF to be the most important determining factor when shopping for and selecting sunscreen. As you may know, SPF, or sun protection factor, is a measurement of how well a given sunscreen can absorb or deflect solar radiation. In general, higher numbers indicate better protection—especially when it comes to defending your skin against painful red sunburns.

But SPF isn’t the only thing that matters where sunscreen is concerned: You also want to make sure that the product you’re buying is labeled “broad-spectrum.” This designation indicates that your sunscreen protects against the two main types of solar radiation, known as UVA rays and UVB rays. Though both types can be harmful, they each affect your skin’s health and appearance in different ways. One tends to cause temporary damage, like sunburns, while the other is associated with long-term skin changes, including visible skin aging.

Here, we’re going in-depth on UVA vs. UVB rays. You’ll learn what UV radiation is, how the two main types of solar radiation differ, and what they do to your skin. We’ll also provide tips for protecting yourself from the sun’s damaging rays all year long. Settle in and read on for your guide to UV rays.

What Is Ultraviolet Radiation?

As you may or may not remember from your high school physics class, ultraviolet radiation, or UV radiation, is a type of energy emitted by the sun. Unlike sunlight, ultraviolet radiation is invisible to the naked eye. Most of the sun’s UV radiation never reaches the Earth’s surface, thanks to the ozone layer. Of the UV rays that do reach us, the majority is in the form of ultraviolet-A (UVA) rays, while the remainder is shorter-wavelength ultraviolet-B (UVB) rays. A third type of ultraviolet radiation (known as UVC radiation) also exists; however, these rays cannot pass through Earth’s atmosphere.

Like all forms of radiation, UV rays are hazardous to human health. They’re particularly dangerous for areas frequently exposed to sunlight—in other words, the skin. While both UVA rays and UVB rays are dangerous, they affect the body in very different ways. Ahead, we’ll dive deeper into UVA vs. UVB radiation, starting with UVA rays.

What Does UVA Radiation Do?

Research shows that UVA radiation accounts for approximately 99% of the solar radiation that reaches the Earth’s surface.I Shorter-wavelength UVA rays can penetrate the skin’s inner layers, whereas UVB rays damage the outermost surface layer. In the short term, exposure to UVA rays encourages the body to produce melanin and develop a tan. Over time, UVA radiation can also cause oxidative stress and widespread cellular skin damage. This damage, known as photoaging, is responsible for nearly 80% of visible skin aging.II Long-term exposure to UVA radiation is also a major cause of skin cancer.

It’s worth noting that UVA radiation can penetrate through windows and even heavy clouds. As such, it’s important to wear sun protection every day, even if you’re not in direct sunlight. For your basic daily line of defense, we recommend incorporating an SPF moisturizer, like Ultra Facial Cream SPF 30, into your skincare routine. This lightweight moisturizer with olive-derived squalane and glacial glycoprotein absorbs quickly to nourish the skin with 24-hour hydration. It also defends against skin-damaging ultraviolet rays with broad-spectrum SPF 30. The non-greasy formula is suitable for all skin types and can be used daily to help promote balanced, healthy-looking skin.

To address age-related skin concerns while protecting your skin against further sun damage, try an anti-aging SPF moisturizer, like Super Multi-Corrective Cream SPF 30. This effective face cream for mature skin helps improve the visible signs of skin aging, such as fine lines and wrinkles, dullness, and uneven skin texture. It also hydrates the skin and offers SPF 30 protection from both UVA and UVB rays. Apply it to your face and neck as the last step in your anti-aging skincare routine for smoother, firmer-looking skin with continued use.

Don’t forget to protect your lips, too. Swap out your usual lip balm for an SPF version, like Butterstick Lip Treatment SPF 30. The coconut oil-infused formula helps hydrate dry lips and provides broad-spectrum protection against UVA and UVB rays. Try the clear balm for a natural finish, or pick from one of our five tinted varieties for a subtle wash of color. Smooth on any shade in the morning and make sure to re-up throughout the day.

What Does UVB Radiation Do?

While UVB rays only make up a small percentage of the solar radiation that reaches the skin, they’re still dangerous. The vast majority of UVB radiation is absorbed by the epidermis, or the outermost layer of the skin.

It’s responsible for the immediate side-effects we typically associate with excessive sun exposure, namely sunburns and inflammation. Like UVA radiation, long-term exposure to UVB rays is known to cause cell death and skin cancer, especially for those with fairer skin.

Protecting your skin from both types of solar radiation requires using a broad-spectrum sunscreen with an SPF of at least 15 every day (not just in the summer). Try Super Fluid Daily UV Defense 50+, which offers long-lasting protection against both UVA and UVB rays. The lightweight, non-comedogenic formula also helps protect your skin from other damaging environmental stressors, like air pollution.

When you are in direct sunlight, be sure to apply your SPF at least 15 minutes before going outside and reapply it every two hours or after sweating or swimming.III If you’re wearing makeup, you can try a sunscreen powder for reapplication.

What Else Can You Do To Help Protect Yourself From Sun-Induced Skin Damage?

Though sunscreen is necessary for sun protection, it alone isn’t enough. Experts recommend following other sun-safety measures whenever possible. When outside, stay in the shade if you can, avoid direct sunlight at midday, and try to cover exposed areas (like your scalp) with protective clothing and accessories.

To keep your skin looking its best, we also recommend bolstering your routine with skincare products designed to help strengthen your skin’s natural moisture barrier. This barrier is the first line of defense between your skin and the outside world. And as such, it’s uniquely vulnerable to the damaging effects of environmental stressors like sunlight and air pollution. These factors generate free radicals, which cause oxidative stress and damage your skin. Antioxidants, such as vitamin C, neutralize these skin-damaging compounds.

To keep your skin looking its best, bolster your routine with a lightweight antioxidant serum, like Daily Reviving Concentrate. This non-comedogenic face oil, made with sunflower oil and ginger root essential oil, defends skin from free radicals and helps correct the visible signs of fatigue. It’s suitable for all skin types and can be used every morning to help promote glowing, radiant-looking skin.

We also recommend adding a strengthening serum to your morning and nighttime skincare routine. Try Vital Skin-Strengthening Hyaluronic Acid Super Serum. This potent hydrating serum, which boasts a powerful blend of adaptogenic herbs, helps diminish the appearance of fine lines and improves skin’s texture for a visibly more youthful appearance.*

*Based on a four-week clinical study of 58 participants tested in urban and polluted environments.

I. Encyclopedia Britannica Editors. “Ultraviolet Radiation.” Encyclopedia Britannica. 18 May 2020.
II. Zhang, Shoubing, and Enkui Duan. “Fighting against Skin Aging: The Way from Bench to Bedside.” Cell transplantation vol. 27,5 (2018): 729-738. doi:10.1177/0963689717725755
III. “Sunscreen: How to Help Protect Your Skin From the Sun.” United States Food and Drug Administration. 29 Aug 2019.

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