You’ve definitely seen the letters ‘SPF’ on your sunscreen bottle, but what about ‘PA’? The PA+ rating system is another measurement for sun protection, but what does it stand for and what do all the ‘+’ signs after it indicate?
SPF stands for Sun Protection Factor, and measures how long you receive protection from the sun’s UVB rays (or the ultraviolet rays that cause sunburn).
The letters ‘PA’ stands for Protection Grade of UVA, and measures none other than a sunscreen’s ability to block UVA rays (the ultraviolet rays that cause skin damage). The PA rating system is more commonly seen in Asia. Japan developed the PA system by adapting the Persistent Pigment Darkening (PPD) method, which determined how long it took the skin to tan. PPD does not have standardized scoring, so the amount of UVA exposure an individual can handle when wearing sunscreen cannot be measured precisely.
In the PA system, PPD results are grouped together and converted in the following way:
- If a product’s PPD = 2 to 4, PA = PA+
- If a product’s PPD = 4 to 8, PA = PA++
- If a product’s PPD = 8 to 16, PA = PA+++
- If a product’s PPD = 16 or higher, PA = PA++++
More ‘+’ signs at the end indicate higher protection with PA++++ being the highest level of protection you can get from UVA rays. There is no way for general consumers to tell if a PA++++ product has a PPD greater than 16, so its best to assume its lowest value of being able to protect you 16 times more than having no sunscreen. Not all people tan at the same rate or from the same sun exposure, so the PA+ rating system only provides a general protection level.
For best protection from the sun, look for sunscreen labeling that says “broad-spectrum” or has both SPF and PA measures. SPF and PA are proportionate, so higher SPF ratings correlate to high PA+ rating.
Some recommended sunscreens that use the PA+ system: