Welp, it turns out that your sun-protection-obsessed mother might have been right to insist you wear SPF 100. Despite the Food and Drug Administration’s stance that anything over SPF 50 does not offer significant additional protection, a new study suggests that that might not be true.
The study, published in the Journal of the American Academy of Dermatology, found that while it’s true that SPF levels over 50 don’t make a big difference in protection if a person applies sunscreen in exactly the correct recommended way (slather your body with enough sunscreen to fill a shot glass and reapply every two hours), most people don’t follow those instructions, in which case SPF 100 does make a difference.
The 199 men and women who participated in the study were given two different tubes of sunscreen labeled “left” and “right,” and told to apply to each corresponding side of their face and neck, before going about their normal activities on a sunny day. One tube contained SPF 50, the other SPF 100.
The results? Sun damage on the SPF 50 side was, on average, twice as high as on the SPF 100 side. Whoa. And the reason for such a large disparity was pretty darn relatable: People almost never apply enough sunscreen.