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 rightfully so, knowing that sun exposure causes up to 80% of the visible signs of skin aging.
But the sun isn’t public enemy number one. Its health benefits keep us energized, and its mood-boosting effects give us that finally-summer-feeling we know and love. So if you’re curious about how to enjoy the sun while protecting your skin, learning about different types of solar and ultraviolet (UV) radiation is key.
Let’s dive in with the help of one of our favorite experts, ISDIN Medical Affairs Specialist Chiyoung Kang Park.
What is the solar spectrum?
The sun plays a vital role in our health, contributing to our mental well-being and helping our bodies produce vitamin D. But it also emits something called electromagnetic radiation. While some of it is absorbed, scattered, and reflected before it reaches the Earth, the radiation that does reach us is called the solar spectrum.
The solar spectrum is made up of various types of radiation, grouped by their electromagnetic frequencies. You’ve likely heard of a few, like ultraviolet A (UVA) and ultraviolet B (UVB). 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). Let’s take a look at how each of them impacts your skin.
What’s the difference between UVA & UVB radiation?
UVB radiation
Responsible for summertime tan lines, these high-energy rays mostly affect the outer layer of your skin.UVB exposure depends on the time of day, location, and weather—but it can occur even 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 that help repair damage, frequent burns can weaken the skin’s ability to regenerate—increasing the risk of skin cancer.”
UVB radiation cheatsheet
Main skin concern: Sunburns and their link to skin cancer
Where does exposure happen? Outdoors all year round, although levels vary by climate and season
Extra credit: SPF, or sun protection factor, refers specifically to UVB protection. Dermatologists recommend choosing SPF 30 or higher.
UVA radiation
On the other hand, UVA rays have a longer wavelength and reach 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.”
Unlike UVB, UVA rays pass through clouds and glass—meaning you’re exposed even while driving or working indoors near windows.
UVA radiation cheatsheet
Main skin concern: Signs of skin aging, sun allergies, and skin cancer
Where does exposure happen? Indoors and outdoors, year-round
Extra credit: Opt for broad spectrum sunscreen—meaning it meets FDA standards for UVA protection.
Beyond UV: Other types of solar radiation
Solar blue light
High-energy visible (HEV) blue light helps us to see the world around us, literally. But research shows that it may also contribute to visible changes in skin—especially in people with deeper 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.
Science spotlight: People with deeper skin tones are more reactive to blue-violet light. This light can trigger the skin to produce more pigment, even though it’s less likely to burn. That means skin with a higher phototype is uniquely sensitive to pigmentation concerns.
Solar blue light cheatsheet
Main skin concern: Dark spots and uneven pigmentation
Where does exposure happen? Indoors and outdoors, year-round
Extra credit: Solar blue light is 100 to 1000 times more intense than the blue light from artificial sources—making upping your sunscreen use the priority over cutting screen time.
Infrared radiation
Infrared-A (IR-A) is different from UV radiation in a few ways. The most noticeable? It’s hotter. While we can’t feel UV radiation, our skin absorbs IR-A rays from the sun, causing that warm, sunny feeling. It’s even used in some therapies for muscle tension relief.
But infrared radiation can also stress the skin. “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 signs of skin aging
Where does infrared exposure happen? Indoors and outdoors
Extra credit: Infrared or heat exposure is just one of many exposome factors, like pollution or stress, that influence skin health and appearance over time.
Concerned about blue light or infrared exposure? Turn to a sunscreen designed to offer extra defense.
Just the FAQs
Is there a relationship between UV radiation and skin color?
Everyone’s affected by UV radiation, no matter their skin tone. And those effects can include skin cancer—making it incredibly important to use proper sun protection every single day.
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. Even if you don’t burn, it’s important to support your skin with protective clothing, sunscreen, and shaded sanctuaries.
Knowledge is power
While the sun supports well-being, too much exposure can lead to skin aging and health concerns.
Understanding the effects of different types of solar and UV radiation can help you decide what sun care products are right for you. No matter your choice, make sure to include a high SPF broad spectrum sunscreen in your daily routine.
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. https://doi.org/10.1038/jidsymp.2009.7