In this article:
What is the PA sunscreen rating system?
What each PA rating means
Is SPF or PA more important?
How to choose a sunscreen with a good PA index?
What is broad spectrum?
The SPF rating on a sunscreen bottle stands for Sun Protection Factor, a measurement of how long you can stay outside during the day and receive protection from the sun’s burn-causing UVB rays (assuming you’re applying sunscreen the right way) (1). In America, the SPF rating system is common; we run into it every time we purchase sunscreen.
However, the sun doesn’t emit only UVB rays, it emits UVA rays, too. This is where the PA+ rating system comes into play. You might’ve seen this rating system on Asian and European sunscreens you’ve encountered.
If you’re a bit confused and want more information on the PA+ rating system, let us explain how it came about, how it compares to SPF ratings and more, below.
What is the PA sunscreen rating system?
Some sunscreens, most notably those in Asia, include PA+ rating on their products. The letters “PA,” which stand for “Protection Grade of UVA,” followed by plus signs (PA+, PA++, PA+++ and PA++++) that appear on labels are a rating system developed in Japan to represent how much UVA protection a product offers. This UVA “grading” system is now used throughout Asia and is becoming increasingly popular in Europe, but it’s not in use in the United States yet (more on that in a moment).
The sun’s UVA rays do not cause sunburn; rather, they cause skin to turn brown. UVA rays are known as the sun’s silent killers because you don’t feel them affecting skin. Despite the lack of pain associated with UVA rays, they penetrate deeply into skin, causing a somewhat different type of damage than UVB rays.
This is what each PA rating means:
- PA+ = Some UVA protection.
- PA++ = Moderate UVA protection.
- PA+++ = High UVA protection.
- PA++++ = Extremely High UVA protection.
Is SPF or PA more important?
Both the PA and SPF rating systems provide information about the level of protection a sunscreen provides, helping consumers make educated decisions about sun care. One system isn’t better than the other, with each focusing on a different type of ray. However, each has a few blind spots due to the complex nature of UV rays and the damage skin can incur from them.
The PA rating measures how the sun’s UVA rays cause the skin to become brown and stay brown, a process called Persistent Pigment Darkening, or PPD (2). However, not everyone’s skin turns brown from sun exposure, even when exposed only to sun’s UVA rays. In the actual testing to determine the PA rating of a sunscreen, the colour of different people’s skin after UVA exposure is inconsistent; some skin gets darker, some not as dark and some skin takes longer than others to turn brown (and what about people whose skin freckles from UVA light?).
SPF measures how much protection a sunscreen offers from UVB rays. UVB rays vary greatly based on time of day, altitude and distance to the equator. This means that based on time and your location, you may need to reapply your sunscreen more often to truly receive the SPF rating your sunscreen offers.
Protection from UV rays is important and both rating systems offer a helpful foundational idea about just how much protection you’ll receive from your sunscreen! No matter what, it’s always important to remember to use a broad-spectrum sunscreen daily and to reapply every two hours that your skin is exposed to UV light. Checking the UV index to help better inform your daily sun protection plan can help protect skin too.
How to choose a sunscreen with a good PA index?
When choosing a sunscreen based upon its PA number, it’s best – as is the case with sunscreens with SPF ratings – to go with a higher rating. Studies indicate sunscreens rated PA+++ or PA++++ have the best track record when it comes to protecting skin from the effects of photoageing, AKA sun damage (3).
Also important are the usual factors you should consider when selecting a skin care product (and sunscreen is the most crucial skin care product you can use). Make sure that the sunscreen you select is packed with antioxidants to provide extra protection, free of fragrance or other irritants (like high amounts of SD or denatured alcohol), texture-appropriate for your skin type and packaged to keep its ingredients stable over time.
As to why the PA rating system isn’t used in the United States yet, the U.S. Food and Drug Administration has determined that the PPD test used to determine PA was unnecessary because the test used to determine broad spectrum effectiveness was sufficient (4).
Speaking of broad spectrum…
What is broad spectrum?
Regulatory agencies in most countries, especially in the European Union (EU) and in the United States, use SPF ratings to include both UVA and UVB protection. This process more accurately represents a real-world experience of how people’s skin responds when exposed to the sun, not just UVA or just UVB. In these countries, the term "broad-spectrum protection" is on sunscreen products’ labels to indicate that it has passed testing to show it protects from both UVA and UVB damage (5).
According to the U.S. Food and Drug Administration (FDA): Scientific data demonstrated that products that are “Broad Spectrum SPF 15” [or higher] have been shown to reduce the risk of skin cancer and early skin ageing when used with other sun protection measures, in addition to helping prevent sunburn. (6)
Whether a sunscreen uses the PA rating system or not (and it’s neither essential nor a mark of a superior product), a well-formulated sunscreen will provide broad-spectrum protection and, as with any sunscreen, must be applied liberally and reapplied as needed to maintain the labeled level of protection.
Learn more about sunscreen.
References for this information:
- Pharmacognosy Journal, May-June 2016, pages 171–179
- Journal of Investigative Dermatology, May 2017, pages 1,184-1,187
- Optics and Photonics Journal, June 2023, pages 140-146
- TrAC Trends in Analytical Chemistry, December 2022, Article 116724
- Journal of Clinical and Aesthetic Dermatology, January 2013, pages 16–26
- U.S. Food and Drug Administration, Accessed September 2023, Webpage
