Beyond SPF: Why UVA Protection Deserves More Attention ☀️

SPF 50+ is important—but it's not the whole sunscreen story. Let's look at UVA protection, the 380–400 nm range, newer UV-filter technology, and what Australian shoppers need to know when buying Korean sunscreens.

When choosing sunscreen, SPF 50+ is often the first thing we look for.

But SPF isn't the only number that matters.

The sun's ultraviolet radiation reaching the Earth's surface is approximately 95% UVA and 5% UVB. Both UVA and UVB can contribute to skin cancer, while UVA is strongly associated with tanning and photoageing, and UVB is the primary cause of sunburn.

So, for everyday skincare and sun protection, the question isn't simply:

"What's the SPF?"

It's also:

"How well does this sunscreen protect against UVA?"

And this is where sunscreen technology gets particularly interesting.

🌞 1. UVA vs UVB: What's the Difference?

UV radiation is commonly divided into UVA and UVB.

UVB — the main sunburn driver

UVB is the primary cause of sunburn and also contributes to skin cancer.

The SPF rating primarily reflects protection against UVB-related erythema, which is why SPF is such an important measure of sunscreen performance.

UVA — think photoageing and pigmentation

UVA is associated with:

• Tanning
• Photoageing
• Pigmentation
• Cellular and DNA damage
• Skin cancer risk

UVA also makes up the vast majority of UV radiation reaching the Earth's surface.

This is why broad-spectrum sunscreen matters.

In Australia, the TGA defines broad spectrum as protection against both UVA and UVB.

🔬 2. UVA Isn't Just One Wavelength

UVA covers approximately 320–400 nm.

It's often divided into:

UVA-II: approximately 320–340 nm

UVA-I: approximately 340–400 nm

And within the longest part of UVA, you'll increasingly hear skincare brands discussing:

380–400 nm — ultra-long UVA

This is still UVA. It isn't a separate type of radiation.

Rather, it represents the longest-wavelength end of the UVA spectrum.

Think of it like a gradient:

UVB → shorter UVA → longer UVA → 380–400 nm

The interesting part is that different UV filters absorb different portions of this spectrum.

Some are particularly strong in UVB.

Others are stronger in UVA.

And some newer technologies have been developed specifically to improve filtration toward the longest UVA wavelengths.

📏 3. Peak Absorption vs Overall Coverage

This distinction is important when reading sunscreen marketing.

A UV filter can have a maximum or peak absorption wavelength.

For example, a filter may have particularly strong absorption around 385 nm.

But that does not mean the filter only works at 385 nm.

Nor does a peak absorption wavelength tell you the complete protection performance of the finished sunscreen.

Think of it like a mountain:

Peak = the highest point

Coverage = the width and shape of the mountain

A modern sunscreen formula usually combines several UV filters with complementary absorption profiles.

The result is intended to provide protection across a wider part of the UV spectrum.

So when comparing sunscreens, it's more useful to consider the finished product's tested protection rather than choosing a product solely because it contains one particular filter.

💜 4. Why Is 380–400 nm Getting So Much Attention?

One of the best-known examples is Mexoryl 400, used in L'Oréal's UVMune 400 technology.

The TGA lists the ingredient under the name:

Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate

The TGA's guidance identifies its maximum absorption at approximately 385 nm, placing its strongest absorption within the ultra-long UVA region. It is an ingredient permitted for use in Australian listed therapeutic sunscreens, subject to the applicable requirements and permitted concentration.

This technology is interesting because it specifically addresses a part of the UVA spectrum that has historically been more difficult to cover efficiently with individual UV filters.

But here's the important part:

A 385 nm absorption peak does not mean "385 nm protection only."

And a sunscreen advertised as having "400 nm protection" should not automatically be interpreted as providing the same level of protection at every wavelength from 380 to 400 nm.

The finished sunscreen formula and its testing are what matter.

🧪 5. Newer UV Filters: It's About the Whole Filter System

Modern sunscreens don't usually rely on one UV filter.

Instead, formulators combine filters with different absorption characteristics.

For example, a formula might include filters particularly effective in:

UVB + UVA-II + UVA-I + longer UVA wavelengths

This approach can create a more balanced protection profile.

Some modern filters commonly encountered in Korean, Japanese and European-style sunscreen formulations include ingredients such as:

Diethylamino Hydroxybenzoyl Hexyl Benzoate (DHHB)

A UVA filter particularly useful for longer UVA protection.

Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (BEMT)

A broad-spectrum filter that absorbs across UVA and UVB.

Ethylhexyl Triazone (Uvinul T 150)

A highly efficient UVB filter that can help achieve high SPF in modern lightweight formulations.

Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (MBBT)

A broad-spectrum particulate UV filter covering UVA and UVB.

Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate

The ingredient associated with Mexoryl 400, particularly interesting for the ultra-long UVA region