PA stands for "Protection Grade of UVA", i.e. the level of protection against UVA rays. PA+ ratings measure a product's ability to block UVA rays.
Developed in Japan, the PA rating system is based on the PPD (Persistent Pigment Darkening) method. This test relies on exposure to UVA rays to induce persistent tanning of the skin, making it possible to assess how long it takes before the skin tans.
In theory, a sunscreen with a PPD value of 10 would enable a person to withstand 10 times more UVA exposure before tanning. However, PPD values cannot be measured with perfect accuracy. As there is no standardized system for assessing PPD scores, different rating systems are used in different countries to indicate the strength of UVA protection. PPD therefore does not give an exact amount of UVA protection, but is converted according to the rating system in force in each country or region.
Only some countries use UVA tests, notably Japan, the UK, Germany, the USA and Australia. In Japan, PPD results are grouped and simplified in the form of PA labels.
The equivalences are as follows:
- If PPD = 2 to 4 → PA+.
- If PPD = 4 to 8 → PA++
- If PPD = 8 to 16 → PA+++
- If PPD ≥ 16 → PA++++
It's important to note that not all countries use the same rating system, as PPD is not standardized internationally.
In a nutshell, PA+ means you have some UVA protection, and the more "+" there are, the higher the protection. Currently, the highest level of UVA protection available is PA++++.