For many years, we didn’t worry about providing UVA protection in sunscreens. But we have learned that UVA exposure also causes damage to our skin. It doesn’t generally cause sunburns unless you have a known sensitivity to UVA, as in lupus or some medication-related photosensitivity. But UVA is associated with more of the signs of “aging”. Wrinkles, bruising, thin skin, and discoloration are all associated to chronic sun damage, without sunburns. Precancers, called actinic keratoses, and squamous cell carcinomas, have been found to be more strongly associated with chronic long-term UVA exposure, while basal cell carcinomas and some melanomas are more strongly associated with acute sunburns.
So why shouldn’t we worry about UVA protection? That’s because ALL currently available sunscreens sold in the US are required to provide UVA protection. So any sunscreen you buy must have UVA protection. While there was a movement to use a UPF rating, or Universal Protection Factor, which included UVA protection, to distinguish from sunscreens without UVA protection, using the SPF rating, or Sun Protection Factor, once the requirement for all sunscreens to provide UVA protection was mandatory, the UPF became unnecessary.