When it comes to protection against the sun's harmful rays, it stands to reason that the higher a sunscreen's SPF (sun protection factor), the better protection provided.
Not so fast. As it turns out, there comes a point when it's about as good as it's going to get. With some companies touting sky-high SPFs, consumers start to wonder how high is high enough.
Start with the basics.
A sunscreen's SPF measures the degree of protection against sunburn-causing UVB rays. Those who slather on the sunscreen might not burn but they have to make sure they're receiving adequate protection against the skin-damaging radiation in UVA rays.
According to Anjana Patel, a physician's assistant at North Atlanta Dermatology, SPF 30-45 is adequate to provide sun protection. SPF 15 blocks about 94 percent of UVB rays, SPF 30 blocks about 97 percent, and SPF 45 blocks about 98 percent. Once the numbers start getting higher than this, little difference is seen in the amount of protection a person is getting.
"A sunscreen with SPF 100 may also give a false sense of security and make a person think they are protected for a long time," Patel says. "What is almost more important than SPF rating is reapplication of sunscreen every two hours when outdoors."
The American Academy of Dermatology recommends choosing a broad spectrum sunscreen that protects against both UVA and UVB rays. It's important to note that the higher SPF sunscreens last the same about of time as the lower ones. If you think a sunscreen with SPF 100 allows you to stay out in the sun twice as long as SPF 50, you're sorely mistaken--or you will be once the sunburn hits its stride.
Keep in mind that testers evaluating SPFs apply two milligrams of sunscreen per square centimeter of skin, compared to the 0.5 to 1 milligram per square centimeter that most people use. Translation: The actual SPF they achieve is about one-third of the labeled value so make sure to apply enough sunscreen, which for an average-size body is two ounces.
"I recommend applying a little extra on the shoulders, chest and face to make sure they are well protected," Patel says. "I tend to see a lot of sun-related problems in these areas like skin cancers, wrinkles and discoloration."
She suggests choosing a sunscreen that contains either zinc oxide or avobenzone in order to block both UVA and UVB rays.
"I prefer zinc oxide-containing sunscreens because it is a physical block rather than a chemical block," Patel says. She recommends wearing protective clothing when spending time outdoors, whether for tennis, golf or gardening.
The Food and Drug Administration requires sunscreens to retain their strength for at least three years. However, if you're using enough of the product as often as you should, an average bottle of sunscreen would never last that long. And if the posted expiration date has passed, throw it out.
Remember that no SPF offers 100 percent protection, but the best type is one you will use on a consistent basis.
