In the context of sunscreens, "++" doesn't directly relate to SPF (Sun Protection Factor). SPF measures protection against UVB rays, which cause sunburn. Instead, "++" is part of the PA rating system, which measures protection against UVA rays, responsible for premature aging and skin damage.
The PA system, developed in Japan, uses plus signs (+) to indicate the level of UVA protection. More plus signs denote higher protection:
- PA+: Offers basic UVA protection (40-50% blockage).
- PA++: Provides moderate UVA protection (60-70% blockage).
- PA+++: Offers high UVA protection.
- PA++++: Provides very high or exceptional UVA protection (blocking over 90% of UVA rays). This indicates approximately 16 times more protection against UVA rays compared to using no sunscreen.
Therefore, "++" in a sunscreen label signifies a moderate level of UVA protection according to the PA rating system. It's crucial to remember that SPF and PA ratings address different types of UV radiation; both are important for comprehensive sun protection. A high SPF with a low PA rating, for example, won't fully protect your skin.
