UV radiation is one of the most significant external factors influencing skin aging and skin health. However, not all UV rays are the same. Distinguishing between UVA and UVB rays is essential when it comes to proper sun protection and preventing light-induced skin damage. In this article, you'll learn:

Contents:

• What are UV rays ?
• UVB – The sunburn rays
• UVA – The neglected danger
  • Why UVA protection is often neglected
  • Is there a natural protection time for UVA?
  • When should you pay particular attention to UVA protection?
  • Approved UV filters with high UVA protection
• Conclusion and product recommendation

What are UV rays?

🌞 UV rays are close to visible light . They have a shorter wavelength and are therefore more energetic than blue/violet light. Hence the name " ultraviolet " (UV). Ultraviolet rays are high-energy light waves emitted by the sun, invisible to the human eye.

UV rays are further divided into three categories. 1️⃣ UVA rays are the lowest energy, but they account for 90% of the UV rays that reach us on the Earth's surface. 2️⃣ UVB rays only penetrate the ozone layer to a small extent. 3️⃣ UVC rays are fortunately completely absorbed by the atmosphere.

There are two types that are relevant for skin care:

• UVB (280–320 nm)
• UVA (320–400 nm)

Both have different effects – both short-term and long-term.

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UVB – The sunburn rays

UVB rays have a shorter wavelength and only penetrate the outermost layer of the skin (epidermis). They are primarily responsible for:

• Sunburn (erythema)
• DNA damage in keratinocytes
• Acute skin inflammation
• Higher risk of skin cancer

A product's sun protection factor (SPF) primarily indicates how well it protects against UVB radiation. For example, an SPF 30 filters out about 97% of UVB rays.

--> See also blog article " How long can I stay in the sun? "

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UVA – The neglected danger

UVA rays have a longer wavelength and penetrate deeper into the skin, down to the dermis . There they cause:

• Oxidative stress caused by free radicals
• Degradation of collagen & elastin (photo-aging)
• Disturbance of melanin regulation (hyperpigmentation)
• Long-term cell damage and skin cancer risk

While UV B rays mainly cause sunburn and skin cancer , UV A rays penetrate deeper into the skin and are primarily noticeable through premature skin aging and hyperpigmentation .

However, UVA rays also contribute approximately 15% to sunburn (especially in skin type I), and long-term exposure also contributes to the risk of skin cancer [1,2]. UVA rays also cause free radicals and inhibit immune cells [3].

While UVB rays are hardly present in our latitudes in winter , UVA intensity fluctuates  less dependent on season, time of day, geography, and altitude [4]. UVA rays are given very little weight in the UV index, so it is primarily an indicator of UVB strength.

Intensity-stable exposure is the main cause of cumulative skin aging due to light.

--> See also blog article " Why sun protection in winter too? "

Why UVA protection is often neglected

🔍 The determination of the UVA protection factor is not as internationally standardized as the SPF (sun protection factor), which primarily indicates protection against UVB radiation . While SPF is well communicated in most products, UVA protection is often not stated or is minimal .

🇪🇺 In the EU, ISO 24443 is primarily used for UVA protection. A measuring device compares the absorption between the UVA and UVB ranges. If the absorption in the UVA range is at least 1/3, the test is considered passed.  

🇯🇵 More common in Japan is an in vivo test according to ISO 24442. Here, the reduced skin tanning between unprotected and protected skin is compared on real test subjects (PPD: Persistent Pigment Darkening).  

There are also different standards for indicating UVA protection:

The EU minimum standard requires only one-third of the SPF as UVA protection (e.g., SPF 30 = UVA PF ≥10). This is sufficient for sunburn protection, but not for optimal slow-aging routines .

UVA-PF (UVA Protection Factor) , PA rating (e.g. PA++++) or the UVA label in a circle can provide clues – but only brands that explicitly state the UVA-PF offer real transparency.

Is there a natural protection period for UVA? (Analogous to natural UVB protection against sunburn)

While the natural protection time against UVB rays for most European skin types is approximately 5-20 minutes , a similar value for UVA rays is difficult to determine. UVA and UVB rays always occur together in the sun's spectrum, and sunburn occurs before UVA rays have even produced a tan .

The most important harmful UVA effect in cosmetics is photoaging . However, it only occurs after years of chronic UVA exposure and cannot be determined for ethical and practical reasons.

Perhaps a more appropriate approach would be to measure the formation of free radicals [5]. However, these are not exclusively triggered by UVA rays.

When should you pay particular attention to UVA protection?

• If you are prone to hyperpigmentation
• For photo allergies e.g. Mallorca acne
• To prevent pimple marks, e.g. in acne
• During pregnancy (increased Sensitivity to pigmentation)

Or if you simply want to use the most effective skincare product to prevent unnecessary skin aging. Happy aging is also possible without preventable signs of deterioration. It's not just about appearance, but also about a healthy skin barrier.

Approved UV filters with high UVA protection:

One or more should be found in your sunscreen:

• Butyl Methoxydibenzoylmethane (Avobenzone, BMDBM)
• Diethylamino Hydroxybenzoyl Hexyl Benzoate (Uvinul® A Plus, DHHB)
• Disodium Phenyl Dibenzimidazole Tetrasulfonate (Neo Heliopan® AP, DPDT)
• Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate (Mexoryl® 400)

As well as broadband filters:

• Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (Tinosorb® S, BEMT)
• Methylene bis-benzotriazolyl tetramethylbutylphenol (Tinosorb® M, MBBT)

--> See also blog article " The best UV filters "

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Conclusion: UVA and UVB both need to be protected

For effective protection:

✅ Pay attention not only to high SPF (at least 30), but also to proven UVA protection
✅ Use broadband filter combinations
✅ Apply sunscreen daily and generously

Anyone who wants to take preventative measures against collagen degradation, pigment spots and loss of elasticity should pay particular attention to the UVA component.

Recommendation:

The Skingineered UVA Booster offers UVA protection that even exceeds UVB protection – a first on the market. For us, this is an important step toward skin-needs-oriented innovation.

Your Ying

Engineer, Cosmetic Scientist and Founder of Skingineered