We’ve all seen SPF numbers creep into the 100s, but what does that high number actually mean and how should we most effectively use the sunscreen? Most dermatologists recommend a broad-spectrum SPF 15-30 daily for routine use and an SPF 30-50 before spending a long amount of time outdoors. The SPF number only shows protection against UVB rays, which most do, but not all of the damage. A broad-spectrum sunscreen (usually containing zinc oxide) will protect against both UVB as well as UVA rays, which are more associated with aging than with sunburn.
For maximal effectiveness and sun protection, I recommend applying a full ounce (2/3 of a shot glass) worth of sunscreen to uncovered areas 15- 20 minutes prior to exposure (even on your lips!). Reapply every 2-3 hours or after swimming, for as long as you intend to be outdoors. If you tend to sweat more, be a little more generous.
Remember, using sunscreen is a quick and easy way to safeguard yourself from some of the most common preventable cancers; let’s all continue to be proactive this summer.