While higher SPF numbers suggest more protection, the increase in UVB protection is not proportionate. An SPF 30 sunscreen blocks about 97% of UVB rays, whereas SPF 50 blocks 98%. Beyond SPF 50, the increase in protection is negligible. High SPF ratings can sometimes mislead consumers into thinking they can stay longer in the sun, which can be toxicologically risky due to prolonged exposure to both UVB and UVA rays.
