SPF, also known as sun protection factor, measures how much UVB radiation a sunscreen can filter out. Dermatologists recommend an SPF of at least 30, which blocks 97 percent of the sun’s UVB rays. Having a high-number SPF does not necessarily protect you for a longer period of time, but instead offers incrementally more protection from the sun’s UVB rays. According to the AAD, no sunscreen in reality can block 100 percent of the sun’s UVB rays.
Many individuals purchase a higher SPF in hopes that they don’t have to reapply. In reality, a high-number SPF does not mean that you can spend additional time outdoors unprotected. Re-application is essential, especially after being in the water or after a vigorous work-out (sweating). Learn more about how to choose the right SPF for you HERE.