By Marissa Gold
Q. What does SPF (or sun protection factor) really indicate? Does it have to do with how strong the protection is, or how long it lasts?
A. A higher SPF means more protection against UVB rays, which cause sun burning. SPF has no relevance to UVA protection and ONLY refers to UVB rays, so look for ingredients like Mexoryl and Helioplex (more on those later) that provide UVA protection, too.
Next Up: The Minimum SPF to Use