The Golden Rules of Sun Protection
SPF 30 is the new 15
As a general rule, SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97%, and SPF 50 blocks 98%. Doctors now typically recommend at least SPF 30at least being the key words. If you have a family history of skin cancer or are vacationing in a tropical spot (where the sun is especially intense), go for 50 or even 70.
Just keep in mind: No sunscreen provides 100 percent protection. So to be as safe as possible, you still need to reapply every two hours and after a swim, even if you used the water-resistant kind, says Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City.