UVB, UVA, Blue Light: Solar Radiation & Your Skin 101

As the years go by, many of us shy away from soaking up the sun. We turn to hats and long cover-ups, worshipping broad spectrum sunscreen over bronzing—and for good reason. Research suggests that sun exposure contributes to up to 80% of visible skin aging.

But the sun isn’t the enemy. It helps to keep us energized, and its mood-boosting effects give us that finally-summer-feeling we know and love. The key is understanding how different types of solar radiation affect your skin so you can enjoy the outdoors while helping protect your skin’s health.

To better understand the science behind sunlight and skin, we turned to one of our favorite experts, ISDIN Medical Affairs Specialist Chiyoung Kang Park.

What is the solar spectrum?

Every day, the sun emits energy in the form of electromagnetic radiation. While some of this radiation absorbed, scattered, and reflected before it reaches the Earth, the radiation that does reach us is called the solar spectrum.

The solar spectrum includes several types of radiation, each with different wavelengths and effects on the skin:

• Ultraviolet (UV) radiation, including UVA and UVB rays
• Visible light, including high-energy visible (HEV) blue light
• Infrared (IR) radiation, which we experience primarily as heat

You’re likely familiar with UV rays. But as Kang mentions, “visible blue light and infrared radiation may also affect how your skin looks and feels.”

This spectrum ranges from the most energetic rays (ultraviolet) to the least (infrared). Understanding the difference between ultraviolet vs infrared—and where blue light fits in—can help you make more informed choices about daily sun protection.

Let’s take a look.

What’s the difference between UVA & UVB radiation?

When comparing UVA vs UVB rays, the first thing to know is that both are forms of ultraviolet radiation, but they affect the skin in different ways.

Here’s a quick summary: UVB rays primarily affect the skin’s outer layers and are strongly associated with sunburn, while UVA rays penetrate deeper into the skin and are linked to photoaging and long-term skin damage.

Together, both UVA and UVB exposure contribute to skin cancer risk, which is why dermatologists recommend broad-spectrum sunscreen to protect against both.

What is UVB radiation?

Responsible for those summertime tan lines, UVB rays are high-energy ultraviolet rays that mostly affect the outermost layers of your skin. 

UVB exposure varies depending on factors like time of day, season, altitude, and geographic location. It’s strongest at midday, in high altitudes, and during summer. However, UVB rays can still reach your skin on cloudy days.

“UVB radiation is a key contributor to short-term skin damage, like sunburns,” explains Kang. “And while our body has antioxidant systems to help repair damage, frequent burns can weaken the skin’s ability to regenerate—increasing the risk of skin cancer.”

On the other hand, UVB rays play a beneficial role by supporting vitamin D production in the skin. This is just one reason why balanced sun exposure (combined with proper protection) remains important.

UVB radiation cheatsheet

Main skin concern: Sunburns and their link to skin cancer

Where exposure happens: Outdoors year-round, although intensity varies by season and location

Extra credit: SPF, or sun protection factor, refers specifically to UVB protection. Dermatologists recommend choosing SPF 30 or higher for daily use.

What is UVA radiation?

Unlike UVB rays, UVA rays have longer wavelengths that allow them to penetrate deeper into the skin. “UVA radiation contributes to long-term damage like photoaging and skin cancer,” says Kang. “It can also lead to solar allergies and certain immune responses.”

Because UVA rays reach deeper layers of skin where collagen and elastin are found, they are strongly associated with visible signs of skin aging, including fine lines, wrinkles, loss of firmness, changes in skin texture, and uneven tone.

Another notable difference between UVA and UVB is that UVA rays can pass through clouds and glass. That means exposure can occur indoors near windows, while driving, and throughout the year regardless of season.

UVA radiation cheatsheet

Main skin concern: Signs of skin aging, sun allergies, and skin cancer

Where exposure happens: Indoors and outdoors, year-round

Extra credit: Opt for broad spectrum sunscreen, which meets meets FDA standards for both UVA and UVB protection.

Beyond UV: Other types of solar radiation

While ultraviolet radiation gets most of the attention, it isn’t the only part of the solar spectrum that interacts with your skin.

Solar blue light

Blue light is part of the visible light spectrum and helps us see the world around us. But despite what you may have heard, the majority of blue light exposure comes from the sun—not digital screens.

Research suggests that blue light and skin may be connected through pigmentation pathways, particularly in people with medium-to-deep skin tones.

“Solar blue light has been linked to uneven pigmentation. And when combined with UV radiation, it can have a compounded effect,” shares Kang.

Solar blue light cheatsheet

Main skin concern: Dark spots and uneven pigmentation

Where exposure happens: Indoors and outdoors, year-round

Extra credit: Solar blue light is much more intense than the blue light emitted by everyday electronic devices. For most people, daily sun protection is likely to have a greater impact on skin health than reducing screen time.

Science spotlight: People with deeper skin tones tend to be more reactive to blue-violet light. Studies suggest that targeted sun protection techniques can make the difference.

What is infrared radiation?

Infrared-A, or IR-A, is different from ultraviolet radiation in a few key ways. The most noticeable? Heat. While we can’t feel UV radiation, our skin absorbs IR-A rays from the sun, causing that warm, sunny feeling.

But warmth doesn’t always mean harmless. “Although it’s the least energetic solar radiation, IR-A rays can penetrate skin and trigger oxidative stress, especially when combined with UV rays,” explains Kang. The result? Wrinkles, loss of elasticity, and dark spots—otherwise known as the signs of photoaging.

Infrared radiation cheatsheet

Main skin concern: Amplifying the visible signs of skin aging

Where exposure happens: Indoors and outdoors

Extra credit: Infrared and heat exposure are part of a collection of daily factors called the exposome—alongside sleep, stress and even pollution—that influence the way skin looks and feels over time.

Concerned about blue light or infrared exposure? Turn to a sunscreen designed to offer extra defense.

Your questions, answered

Is there a relationship between UV radiation and skin color?

Everyone is affected by UV radiation, no matter their skin tone. And those effects can include skin cancer, making daily sun protection essential for all skin phototypes.

That said, different skin tones may show sun damage in different ways. Lighter skin tones are generally more prone to visible sunburn, while medium-to-deep tones may be more likely to experience hyperpigmentation or dark spots after sun exposure.

Some people may also be at greater risk for UV-related damage, especially if they:

• Have lighter skin tones
• Had repeated sunburns during childhood
• Have used tanning beds
• Have a family history of skin cancer
• Are over the age of 50
• Use medications or products that increase UV sensitivity

How do melanocytes help protect the skin from UV radiation?

Your skin tries its best to protect you from the sun’s rays. Skin cells called melanocytes react to solar radiation (mainly UVA rays and blue sunlight) by ramping up melanin production.

Melanin is a protective pigment and a form of natural coloring. In other words, a tan or sunburn is your skin’s way of reacting to and defending itself from sun exposure.

But here’s the important part: a tan is still a sign that your skin has been exposed to UV radiation. Even if you don’t burn, it’s important to support your skin with protective clothing, shade, and daily sunscreen.

What is cumulative sun damage?

Sun damage doesn’t always appear right away. It can build gradually, exposure after exposure, even on days when you don’t burn.

Over time, cumulative damage may contribute to:

• Dark spots and uneven skin tone
• Fine lines and wrinkles
• Loss of firmness
• Rough or uneven texture
• Skin cancer risk

That’s why daily sun protection matters, not just on beach days or during summer. Supporting your skin every day helps protect against the effects you can see now—and the ones that may appear years later.

Knowledge is power

The sun supports our well-being in many ways, from mood to vitamin D production. But too much unprotected exposure can contribute to visible skin aging and long-term skin health concerns.

Understanding the difference between UVA vs UVB, the role of blue light and skin, and the impact of ultraviolet vs infrared radiation can help you can help you land on the right sun care routine.

No matter the season, the forecast, or your skin tone, make high-SPF broad-spectrum protection part of your daily routine. Choose a texture you love, apply it generously, and reapply often.

And above all, love your skin, care for it, and protect it, always.

References:

• GW Lambert, C Reid, DM Kaye, GL Jennings, MD Esler, Effect of sunlight and season on serotonin turnover in the brain, The Lancet, Volume 360, Issue 9348, 2002, Pages 1840-1842
• Jean Krutmann, Anne Bouloc, Gabrielle Sore, Bruno A. Bernard, Thierry Passeron, The skin aging exposome, Journal of Dermatological Science, Volume 85, Issue 3, 2017,Pages 152-161
• Duteil L, Queille-Roussel C, Lacour JP, Montaudie H, Passeron T. Short-term exposure to blue light emitted by electronic devices does not worsen melasma. Journal of the American Academy of Dermatology 2019.
• Khmaladze I, Leonardi M, Fabre S, Messaraa C, Mavon A. The Skin Interactome: A Holistic “Genome-Microbiome-Exposome” Approach to Understand and Modulate Skin Health and Aging. Clin Cosmet Investig Dermatol. 2020;13:1021-1040. Published 2020 Dec 24.
• Cho, S., Shin, M., Kim, Y. S., Seo, J., Lee, Y. H., Park, C. H., & Chung, J. W. (2009). Effects of Infrared Radiation and Heat on Human Skin Aging in vivo. Journal of Investigative Dermatology Symposium Proceedings, 14(1), 15–19.

Amy is a content strategist who turned a part-time obsession with skincare into a full-time passion. Her experience as a creative storyteller includes a range of lifestyle and technology topics across Washington D.C. and Barcelona. What’s in her travel bag? Eye contour cream and sunscreen, always.

Chiyoung Kang Park

Chiyoung is a pharmacist with a great passion for cosmetics. Also graduated in Business Administration and with a Master’s Degree in Dermopharmacy and Cosmetics, she combines her passion for outdoor sports with skincare. Always active, she lives and appreciates both Spanish and Korean cultures, fusing her knowledge and roots in her professional and personal life.