With summer rapidly approaching, it’s the time of year when we are commonly asked: “What sunscreen should I be wearing?” This question also coincides with Consumer Reports annual release of testing results for the nation’s top sunscreen manufacturers. Some of their best buys included Equate sports lotion SPF 50 and Trader Joe’s spray SPF 50, but wearing the highest rated sunscreens does not guarantee adequate protection.
While testing did reveal significant differences in levels of protection between brands and different price points, these results need to be appreciated in the context of typical, real-world use of sunscreens. It is my opinion that proper use of sunscreens far outweighs the differences between sunscreen brands and SPF numbers.
SPF number is a rating system that gives you the relative strength of sun protection to UVB rays relative to the unprotected skin. An SPF of 30 blocks 97% of the sun’s UVB rays. Because it is a logarithmic system, an SPF of 60 does not double your protection but adds a measly 1.5% more protection up to 98.5%. As long as the sunscreen is rated to an SPF of 30, proper use should provide more than adequate protection.
Another area that is commonly misjudged when using sunscreen is its water resistance. Even the most effective water resistant sunscreens only maintain their proper effectiveness for about an hour with water exposure. Sunscreen must be reapplied more frequently when it gets wet. This includes swimming and sweating.
Studies show that most people that apply sunscreens are applying much less than the recommended amount that is required to meet the stated SPF. Applying half the recommended amount will result in half the UVB protection. For sunscreen lotions, 1 ounce (the amount that will fit in a shot glass) should cover a body in a swimsuit. They should also be applied 15 min before wet exposure to maximize water resistance.
Sunscreens that are chemical based lose their effectiveness over time by absorbing harmful UVB rays, and most major brands are using nearly identical combinations of active ingredients. With intense exposure, a sunscreen can lose half of its SPF factor in 2 hours.
So the bottom line is that proper use is far more important than brand differences or SPF numbers over 30. My mantra for good sun protection is to apply the proper amount before sun exposure, then reapply, reapply, reapply, reapply….. And remember, sunscreen is only one part of an overall smart sun protection strategy which should include protective clothing and avoiding exposure during peak hours.