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How do UVA and UVB rays affect the skin?

How do UVA and UVB rays affect the skin?

Learn how to differentiate between UVA and UVB rays and why appropriate sunscreen protection is important.
24 Jul 2021

You likely have a general idea that UVA and UVB rays aren’t a good thing. And you’re right! But do you know what UV rays are and how much damage they can do to your skin? By learning more about the different types of UV rays and how they operate, you can better equip yourself to protect your skin and your health. Here’s what you should know about these ultraviolet rays that we confront on a daily basis.

What are UVA and UVB rays?

Ultraviolet radiation, referred to as UVR, can come from a range of sources. The sun is the natural source of UVR that we all encounter, while lasers and tanning beds are examples of technology designed to create simulated sources of UVR. As invisible energy, UVR is measured on the electromagnetic spectrum by a wavelength that ranges from 100 to 400 nanometers (nm). Various measurements help to identify the three different types and provide a UVR (UVA, UVB, UVC) explanation.

UVA: A as in “aging” or “allergy”

UVA is long-range radiation, measuring between 315 and 400 nm, and makes up 95% of the UVR that reaches the earth’s surface. Exposure to UVA rays is painless; however, they can do long-term damage to your epidermis, causing:

  • skin aging, through the creation of oxidative stress which negatively impacts skin’s youth components leading to aging signs such as fine lines and wrinkles
  • sun intolerance or allergy, which can appear as an itchy red sun rash on exposed skin
  • skin pigmentation issues and the development of dark spots
  • skin cancer on the face and elsewhere on the body

UVB: B as in “burns” or “bronzed skin”

UVB is considered short-wave radiation and measures between 280 and 320 nm. While UVB only accounts for 5% of the UVR that reaches us on earth, exposure to this type can also be detrimental. Exposure to UVB rays can cause a bronzing effect (a suntan), but it can also lead to a sunburn on the face or body. In some cases, you may also develop a skin cancer as a result of UVB rays.

What’s the difference between UVA rays and UVB rays?

Exposure to UVA and UVB rays can affect your skin in different ways. The long-wave radiation of UVA rays causes your skin to produce more melanin and darken to protect itself from harm. There is no such thing as a “healthy” tan as skin produces melanin in order to protect our DNA. the result is immediate tanning or a sunburn depending on your skin tone. And, thanks to their ability to penetrate the epidermis & dermis, UVA rays can also affect cells deeper in the skin. Over time, UVA rays can have a cumulative impact on the appearance and health of skin and contribute to premature skin aging, including a loss of elasticity, the formation of wrinkles and the development of pigmentation spots and roughness as skin’s hydration function is altered. Exposure to both UVB & UVA rays can also lead to the development of some skin cancers. Even though UVA rays have lower energy levels compared to other UV rays, they are prevalent on a daily basis, no matter the season. They make up the majority of UV exposure we receive, and can even go through windows, making it important to protect your skin even if you’re indoors working by a window, or diving in a car.

UVB rays, on the other hand, create direct damage on the top layer of the skin (epidermis). They’re the ones to blame if you experience a case of delayed tanning, a sunburn or blistering. UVB rays are also responsible for most skin cancers, so while they account for a much smaller percentage of UV exposure, the impact can be more dangerous. UVB rays cannot pass through windows.

Wearing a sunscreen lotion or a moisturizer with broad spectrum UV protection on a daily basis is one of the most effective ways to protect your skin from both UVA and UVB rays.

What sunscreen should I use to protect against UVA and UVB rays?

Ultimately, the best sunscreen for you is the one you’ll want to wear on a daily basis. Whether you’re specifically looking for an organic (chemical) sunscreen, mineral sunscreen, a sunscreen meant for the body or a sunscreen for face, it’s best to keep the needs of your skin type in mind. La Roche-Posay has been an expert in developing sunscreen to protect sensitive skin for decades. That said, there are a few key things to keep in mind when making your final selection. Choosing a high sun-protection factor (SPF) is among the SPF recommendations in Canada. Look for a product that offers SPF 30 or higher, such as SPF 50. Another important factor to look for is a circle around the UVA logo, which indicates that the product meets the minimum requirements for UVA protection.

Which sunscreen should I choose for my sensitive skin?

Developed with more than 40 years of research and offering lightweight sunscreen options in cream, mist and stick formulas, the La Roche-Posay Anthelios range is safe for anyone with sensitive skin. Anthelios Ultra-Fluid SPF 50+ Facial Sunscreen is a fragrance-free, ultra-invisible formula that makes an ideal sunscreen for face, while Anthelios Mineral Ultra-Fluid Lotion SPF 50 for Body is the perfect fast-absorbing mineral sunscreen for use on the arms, legs and back and anywhere else on the body. And the Anthelios XL Melt-In Cream SPF 50 line blends classic broad-spectrum UVA and UVB protection with vitamin E and antioxidants designed to address the oxidative damage caused by UVA rays and other exposome factors such as pollution.

How you apply sunscreen is also a big part of successful sun protection. Use a liberal amount (approximately 35 ml for an adult body), always applying SPF 30 minutes before sun exposure and reapplying it every two hours of sun exposure.

How to stay protected against UVA and UVB rays

Now that you know more about UVA and UVB rays and the impact they can have on your skin, here’s a look at the best ways to stay protected:

  • Wear sunscreen lotion with SPF 30 or higher on a daily basis no matter the weather (sunny or cloudy day!)
  • Limit your exposure to the sun between 10 a.m. and 3 p.m.—that’s when UVB rays are strongest.
  • Wear protective clothing, including a wide-brim hat and sunglasses, to reduce UV exposure.
  • Learn more about sunscreen for children and protecting kids from the sun.

Curious about mineral filters in sunscreen or have more sun-care questions? You’ll find more information in The Skin Edit Sun Protection section.

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