Understanding the PA Rating System for Sunscreens

Let's get familiar with sunscreen labeling. I'm sure you've all seen sunscreens labeled with the letters SPF, which stands for sun protection factor. SPF measures how well a sunscreen protects your skin from UVB rays, which are responsible for sunburns. You should always apply sunscreens labeled SPF 30 or higher. The sun also emits UVA rays. Or the rays that contribute to skin aging and skin cancer. Some sunscreens, especially ones produced in Asia, include a PA rating system on their labels as a measure of how much UVA protection they provide after application. PA stands for Protection Grade of UVA. For those who have never seen PA ratings on a sunscreen bottle before, they are represented by the letters PA followed by 1 to 4 plus signs. PA+ indicates some UVA protection, whereas PA+++ indicates the highest level of UVA protection. The PA rating system was adapted from Japan's Persistent Pigment Darkening, or PPD, factor. PPD is an in vivo method that evaluates the pigmentation of skin from UVA. PPD measures are not precise because because the color of different people's skin after UVA exposure is individualized. The level of darkness that the skin reaches and the amount of time it takes for the skin to brown is different between individuals. To standardize the PPD factor, the PA rating system was created. Now, the PA rating is a standard measure of sun protection on sunscreens in Asia and parts of Europe. It has not been practiced in the United States yet.