The importance of sunscreen is undeniable. In the U.S., over 9,500 people are diagnosed with skin cancer every day and one in five Americans will develop skin cancer by the age of 70. Yet, despite this alarming reality, only 13.5% of people wear sunscreen daily. So, what's behind this growing risk?
What is UV radiation?
Ultraviolet (UV) Radiation is a form of energy that comes from the sun and is also emitted by artificial sources, such as tanning beds. There are three types of UV ray that get produced by the sun, each classified by wavelength:
UVA (315-400nm wavelength)
The longest of the three, UVA rays can penetrate to the dermis (the middle layer of the skin). They make up most of the UV radiation that reaches your skin and are responsible for accelerated visible aging, also known as photoaging.
UVB (280nm to 315nm)
Responsible for sunburn and DNA damage that can lead to skin cancer, UVB rays have a shorter wavelength that reaches the outer layer of your skin, the epidermis.
UVC (100-280nm)
With the shortest wavelength, UVC rays are mostly blocked by the ozone layer.
The sun also emits Infrared Radiation (IR). This is responsible for the heat we feel from the sun. It doesn’t directly cause sunburn and DNA damage like UV, but it can still contribute to ageing.
What is the UV index?
Developed in 1994 by the National Weather Service and Environmental Protection Agency, the Ultraviolet Index is a rating scale that tells you how intense the sun’s UV rays are predicted to be when it's at its highest. The higher the number, the more intense the UV radiation and the greater risk of skin damage, with 1 being low and 11+ being extremely high.
When is UV radiation strongest?
UV radiation is the most intense at noon when the sun is at its highest point in the sky, as the rays have the least distance to travel through the atmosphere. This is why you will often hear the advice to avoid direct sun exposure between the hours of 10 a.m. and 4 p.m., particularly in the height of summer.
UV levels are also higher closer to the equator, where the sun’s rays strike at a more vertical angle and the ozone layer is naturally thinner, allowing more UV to pass through.
Do you need to wear sunscreen when it's cloudy?
One of the most persistent myths is that sunscreen is only necessary in summer or on sunny days. While it’s true that UV levels are generally higher in summer, both UVA and UVB rays are present all year round, even on cloudy days. UV intensity also increases around reflective surfaces like snow, sand and water, which bounce rays back onto the skin. That’s why daily sunscreen application is essential, no matter where you are. If it’s daylight, UV is present.
How can the sun damage your skin?
The sun may feel good. But when it comes to your skin, UV rays don't just irritate it, they fundamentally alter how your skin behaves, repairs itself, and defends against damage, setting off a cascade of cellular events that can have long-term consequences–even if they’re not immediately visible.
UV radiation interacts with your skin cells in two ways: by generating free radicals and causing DNA mutations. These processes disturb normal cell function and repair, setting the stage for skin damage that can lead to premature signs of aging and skin cancer. Sunburn may be a short-term sign of sun damage, but the more concerning effects are the result of repeated or prolonged exposure over time. (Discover the full spectrum of cosmetic and health effects of UV exposure in more detail here.)
UVA: Deeper damage
UVA rays can penetrate deep into the dermis, the layer responsible for your skin’s structure and elasticity. This layer contains fibroblasts, which produce collagen and elastin, key proteins that keep your skin firm and resilient. With repeated UV exposure, these fibroblasts become less effective at repairing damage, weakening your skin’s natural support system.
UVA also generates free radicals: unstable, reactive molecules that cause oxidative stress. This stress damages critical components of your skin cells, including proteins, fats and even the mitochondria, the energy producers of the cell. This slows down your skin’s ability to repair and renew itself, weakening its defenses and accelerating signs of aging.
UVB
UVB rays are absorbed primarily by the epidermis, the outermost layer of your skin that you can see. This form of UV radiation can directly damage the DNA of your skin cells, causing mutations that disrupt the integrity of your genetic code. In the short term, this can trigger an inflammatory response, which we recognise as sunburn, but, in the long term, these mutations can accumulate, altering how the cells function.
When your skin detects this damage, it tries to repair it. But this repair process isn’t always perfect. If the cell makes mistakes or fails to repair all of the damage, those mutations can persist. In some cases, this causes uncontrolled cell growth, where abnormal cells continue to replicate and, over time, this can lead to the development of skin cancer.
Sunscreen isn’t optional. It’s skincare’s seatbelt.
At SunsolveMD, we’re here to make daily sunscreen use the standard by creating intelligent, skin tone-inclusive, and texturally elegant mineral formulas that do more than just shield.
References
https://www.skincancer.org/skin-cancer-information/skin-cancer-facts/#:~:text=1%20in%205%20Americans%20will,for%20melanoma%20is%2099%20percent. Accessed 15th April 2025.
Patlola M, Shah AA, Stead T, Mangal R, Ganti L. Sunscreen use amongst US adults: a national survey. Arch Dermatol Res. 2023 Sep;315(7):2137-2138. doi: 10.1007/s00403-023-02603-8. Epub 2023 Mar 17. PMID: 36930290.
https://www.fda.gov/radiation-emitting-products/tanning/ultraviolet-uv-radiation#UVC
Gromkowska-Kępka, K. J., Puścion-Jakubik, A., Markiewicz-Żukowska, R., & Socha, K. (2021). The impact of ultraviolet radiation on skin photoaging — Review of in vitro studies. Journal of Cosmetic Dermatology, 20(11), 3427–3433. https://doi.org/10.1111/jocd.14033
Vechtomova YL, Telegina TA, Buglak AA, Kritsky MS. UV Radiation in DNA Damage and Repair Involving DNA-Photolyases and Cryptochromes. Biomedicines. 2021 Oct 28;9(11):1564. doi: 10.3390/biomedicines9111564. PMID: 34829793; PMCID: PMC8615538.