If you’re someone who pays attention to skincare labels and ingredients, you probably already know that SPF only tells part of the story. SPF ratings measure how well a sunscreen protects you from UVB rays, the ones that cause sunburn. But there’s another type of sun damage that’s just as important: UVA exposure.

UVA rays go deeper into the skin and are one of the main reasons we get wrinkles, dark spots, and other signs of premature aging. They’re also linked to long-term health risks like skin cancer. Unlike UVB rays, UVA rays are around every day of the year, even when it’s cloudy or you’re sitting near a window inside.

That’s why more people are turning to European and Asian sunscreens, which often use stricter testing methods and clearer labels for UVA protection. If you’ve ever seen terms like UVA-PF, PPD, or PA++++ and wondered what they mean, you’re not alone. The guide below walks you through the basics so you can make more informed choices about the sunscreen you use.

Why UVA Protection Matters for Your Skin

UVA rays make up about 95% of the UV radiation that reaches Earth’s surface, and they’re around all day, every day, rain or shine. UVB rays mostly affect the top layers of your skin, causing sunburns and redness that you can usually feel as heat, burning, or stinging. UVA rays, on the other hand, are more subtle and penetrate deeper, doing damage you might not notice right away. You won’t feel them, but over time, they can cause:

• Fine lines and wrinkles by weakening the skin’s structure
• Dark spots and uneven skin tone
• Long-term DNA damage that can raise the risk of skin cancer

These rays can even pass through windows, so you’re still exposed while driving or sitting near natural light indoors. That’s why UVA protection matters every single day, not just when you’re spending time outside.

Understanding UVA Ratings: UVA-PF, PPD, and PA++++

Sunscreens around the world don’t all use the same way to rate UVA protection. Some use numbers, some use symbols, and some use plus signs. Knowing what each system means can make it easier to find a sunscreen that fits your needs and gives you the right kind of protection.

What Is UVA-PF?

UVA-PF stands for Ultraviolet A Protection Factor. It tells you how well a sunscreen blocks UVA rays, which are the ones responsible for long-term skin damage like wrinkles, dark spots, and even skin cancer. Unlike SPF, which only measures UVB protection, UVA-PF focuses on the deeper, aging rays.

It’s not a test itself, but a score based on how much UVA light the sunscreen filters out. This number is usually determined using methods like the PPD test or ISO 24443 (a lab-based method used in Europe).

In European sunscreens, the UVA-PF must be at least one-third of the labeled SPF to qualify as "broad-spectrum." If you see a UVA symbol inside a circle on the packaging, that’s a quick way to tell the product meets this standard.

For example:

• An SPF 50 sunscreen would need a UVA-PF of at least 16.7 to meet this standard.
• The higher the UVA-PF, the stronger the protection against UVA-induced aging and sun damage.

How Is UVA-PF Determined?

There are two main ways scientists figure out how well a sunscreen protects against UVA rays:

• In vivo (on real skin) – This method, called the PPD test, involves applying sunscreen to a test subject's skin and seeing how long it takes for their skin to start darkening from UVA rays, compared to skin without sunscreen.
• In vitro (in the lab) – In this method, sunscreen is applied to a special surface that mimics skin. Then, lab equipment measures how much UVA light passes through it. One of the most common lab methods is called ISO 24443.

Both methods are considered reliable, and different regions may use one or the other depending on their standards.

Once you understand how UVA-PF is calculated and determined, it’s easier to see how other systems compare.

UVA Star Rating System

In the UK, you might come across the UVA Star Rating system, which was originally developed by Boots. This system doesn't measure the absolute strength of UVA protection like UVA-PF does. Instead, it looks at the ratio of UVA to UVB protection using lab-based (in vitro) testing. Sunscreens are rated from 0 to 5 stars, with 5 stars meaning the UVA/UVB protection is very well balanced (a ratio of 0.90 or higher), while lower ratings reflect less balance between the two.

Here’s a quick breakdown of what each star level means:

UVA Star Rating Scale

A sunscreen can meet the EU’s UVA-PF standard and still receive a lower star rating if the balance between UVA and UVB protection isn’t as close. That’s why dermatologists in the UK often recommend choosing sunscreens with at least 4 stars, especially for daily use. The UVA star rating system is unique to the UK, but you may see it appear alongside the EU’s UVA-in-a-circle symbol on some packaging.

While the UVA star rating focuses on the balance between UVA and UVB protection, other systems like PPD measure how much UVA protection a product actually delivers.

What Is PPD?

PPD stands for Persistent Pigment Darkening, which is a test done on skin to see how much longer it takes for sun-protected skin to start tanning or darkening from UVA rays compared to bare skin. It's one of the main ways scientists measure how well a sunscreen blocks UVA rays and is also what the PA rating system is based on in Asia.

How Is PPD Categorized?

PPD values generally fall into these categories:

• PPD 2-4: Low UVA protection
• PPD 4-8: Moderate UVA protection
• PPD 8-16: High UVA protection
• PPD 16+: Very high UVA protection

PPD values aren’t always listed on packaging, but they are a reliable indicator of UVA performance when available.

What Is the PA System?

PA stands for Protection Grade of UVA. It’s a system developed in Japan to make UVA protection ratings easier to understand. Instead of showing a technical number, it uses plus signs (ranging from one to four) to give you a quick sense of how much UVA protection a sunscreen offers.

What are the PA Rating Levels?

This rating system is used mainly in Japan and South Korea, and it’s based on results from the PPD test. Here’s how the levels compare:

PA Rating	PPD Value	UVA Protection Level
PA+	PPD 2–4	Low protection
PA++	PPD 4–8	Moderate protection
PA+++	PPD 8–16	High protection
PA++++	PPD 16+	Very high protection

A sunscreen labeled PA++++ provides very high protection against UVA rays, although this doesn’t reflect its UVB (SPF) performance, so both values matter.

How Is UVA Protection Labeled in the U.S.?

In the U.S., the term “broad-spectrum” is regulated by the Food & Drug Administration (FDA), but it doesn’t give you the full picture when it comes to UVA protection. Instead of requiring a specific UVA-PF or PPD score like in Europe or Asia, American sunscreens only have to pass something called the critical wavelength test. This test checks whether the sunscreen absorbs UVA rays up to a certain point on the spectrum, specifically 370 nanometers or more.

Here’s what that means in practice:

• A sunscreen in the U.S. can be labeled “broad-spectrum” even if it doesn’t block much UVA radiation.
• Brands don’t have to list their UVA-PF or PPD values on the packaging, so it’s harder to tell how much UVA protection you’re actually getting.

The FDA has proposed stronger guidelines, such as requiring a UVA/UVB ratio of at least 0.7 for SPF 15 and higher, but those changes haven’t gone into effect yet.

Not All Products Disclose UVA-PF or PPD

Even in places with stronger sunscreen regulations, it’s not a guarantee that you’ll find UVA-PF or PPD values on the label. Some brands choose to include this info to be more transparent, but many still leave it off, even if their products meet the standard.

If UVA protection is something you really care about, it’s worth doing a little extra research. Check the brand’s website or look at trusted third-party reviews to see if there is any mention of UVA-PF or PPD testing results.

Photostability: A Key Part of Long-Lasting Protection

Another important thing to keep in mind is photostability, which refers to how well a sunscreen holds up after being exposed to sunlight. Some sunscreen ingredients, like avobenzone, can break down when they sit in the sun for too long. When that happens, the product stops offering as much UVA protection, even if the SPF number still looks good.

To make sure you’re getting reliable protection, try to find sunscreens that:

• Say they’re "photostable" or offer long-lasting UVA protection
• Use more modern, stable filters like Tinosorb or Mexoryl SX/XL

One thing to know: filters like Tinosorb and Mexoryl are considered some of the most effective and stable options, but they’re not yet approved for use in U.S.-made sunscreens because they’re still waiting for FDA review. You can find them in sunscreens from Europe, Canada, and other regions with broader ingredient approvals.

How These UVA Ratings Compare

System	Region	What It Measures	How It’s Determined
UVA-PF	Europe	Level of UVA protection	Derived via PPD or ISO 24443
UVA Star Rating	UK	UVA/UVB balance (not absolute UVA-PF)	In vitro UVA to UVB absorbance ratio
PPD	Europe, Asia	In vivo method to measure UVA-PF	Human skin pigmentation testing
PA System	Asia	Consumer-facing label	Based on PPD value
Broad-Spectrum	U.S.	Absorption across UVA/UVB range	Critical wavelength test ≥370 nm

How to Choose a Sunscreen with Strong UVA Protection

If you want a sunscreen that truly protects your skin, not just from sunburn but also from things like wrinkles and dark spots down the line, here’s what to keep in mind:

• In Europe – Check for a "UVA" symbol inside a circle. This means the sunscreen meets the rule that UVA protection must be at least one-third of the SPF.
• In the UK – Look for the UVA star rating, which shows how balanced the UVA and UVB protection are. Aim for 4 or 5 stars for solid daily coverage.
• In Asia – Look for sunscreens labeled PA++++. The more plus signs, the stronger the UVA protection.
• In the U.S. – Since UVA protection isn’t always shown on the label, try to choose brands that share their test results. Or consider using products from Europe or Asia, where the standards are stricter.
• Make sure the product is photostable, meaning it holds up well in the sun without breaking down and losing effectiveness.

It’s a lot of information to take in, but learning how UVA protection works can help you choose the sunscreen that best fits your skin needs and your daily lifestyle.

The Essential Takeaway: UVA Protection Is Key to Healthy Skin

SPF is only part of the story. UVA rays contribute to premature aging and cumulative skin damage, and without proper protection, you could be leaving your skin vulnerable, even indoors or on cloudy days.

By understanding UVA-PF, PPD, and PA ratings, you can make better choices about the sunscreens you use and how you protect your skin daily. And for additional peace of mind, pair your sunscreen with UPF 50+ clothing. It offers broad-spectrum protection by blocking both UVA and UVB rays and doesn’t need to be reapplied like sunscreen.

Your skin will thank you for it, both now and in the future.

Live well under the sun™

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