Did you know SPF30 sunscreen already blocks 97% of the sun's rays? The SPF ratings system should be changed-- It's so misleading, it's like false advertising. And that explains why it's so easy to get sunburned. SPF 50 only blocks an additional 1%. And SPF 100 only blocks one more 1%. If you put on 70, 90 or 100 you may have thought you're nearly doing something excessive. The reality is if you use a tiny little bit of 100 on your arm it's more or less like using a tiny little bit of 30! You had better use the SAME amount since they're virtually the same!