What’s Your SPF?

By National Cancer Institute , via Wikimedia Commons

And does it matter? We have on numerous occasions heard/discussed the importance of summer safety, chief among which is the use of sunscreen. But there was a New York Times article a few years ago suggesting that using sunscreens with a higher SPF may not really be that helpful. “Consumers should worry more about wearing enough sunscreen, several doctors said, rather than how high their SPF is.”

Should we disregard the SPF? What’s SPF anyway? Let’s see if we can shed some light (terrible joke, sorry). The Mayo Clinic tells us, “SPF stands for sun protection factor, which is a measure of how well the sunscreen deflects UVB rays. Manufacturers calculate SPF based on how long it takes to sunburn skin that’s been treated with the sunscreen as compared with skin that hasn’t been treated with sunscreen.”

They go on to explain:

Theoretically, the best sunscreen has the highest SPF number. It’s not that simple, however. When applied correctly, a sunscreen with an SPF of 30 will provide slightly more protection from UVB rays than does a sunscreen with an SPF of 15. But the SPF 30 product isn’t twice as protective as the SPF 15 product. Sunscreens with SPFs greater than 50 provide only a small increase in UVB protection.

There’s also the question of how well a sunscreen lasts. The American Melanoma Foundation points out that how well the sunscreen stays on after swimming or sweating is just as important as the SPF level. They explain that FDA deems a product “water-resistant” if it maintains its SPF level after 40 minutes of water exposure, and “waterproof” if it maintains its SPF level following 80 minutes of exposure to water.

There is also apparently a difference between sunscreen and sunblock. Sunscreens are divided into two types: chemical and physical. Chemical sunscreens have ingredients filters and reduce ultraviolet radiation, often containing UVB-absorbing chemicals and UVA absorbers. Physical sunscreens are usually called sunblocks; they are products with ingredients such a titanium dioxide and zinc oxide that block UVR. Sunblocks provide broad protection against both UVB and UVA light, but people often pass on them because they can be messy, visible, and not easily washed off.

Whoa, that’s a lot of info on sunscreens, but what do we really need to know to keep safe? According to the Skin Cancer Foundation, it’s good to know about the product, but more important to know about the application:

To ensure that you get the full SPF of a sunscreen, you need to apply 1 oz – about a shot glass full. Studies show that most people apply only half to a quarter of that amount, which means the actual SPF they have on their body is lower than advertised. During a long day at the beach, one person should use around one half to one quarter of an 8 oz. bottle. Sunscreens should be applied 30 minutes before sun exposure to allow the ingredients to fully bind to the skin. Reapplication of sunscreen is just as important as putting it on in the first place, so reapply the same amount every two hours. Sunscreens should also be reapplied immediately after swimming, toweling off, or sweating a great deal.

So buy a high-quality product with an SPF of 15 or higher and make sure it offers broad-spectrum protection. Also look for The Skin Cancer Foundation’s Seal of Recommendation, “which guarantees that a sunscreen product meets the highest standards for safety and effectiveness.” Also keep in mind, you should not rely on sunscreen alone. Follow The Skin Cancer Foundation’s Prevention Guidelines, and avoid falling for these myths:

  1. Sunscreen isn’t needed on cold or cloudy days. Not true–up to 40 percent of the sun’s ultraviolet radiation reaches the earth on a cloudy day.
  2. Sunscreen use encourages excessive sun exposure and, as a result, increases the risk of skin cancer. Most experts disagree with this claim, and research also hasn’t shown a link between sunscreen use and an increase in the risk of skin cancer. Research, however, has shown that use of sunscreen can reduce the risk of melanoma, the most serious type of skin cancer.
  3. Using sunscreen can cause vitamin D deficiency. Most dermatologists believe that sunscreens do not cause vitamin D deficiency. Plus, vitamin D is readily available in supplements and several foods.
  4. Most of your sun exposure comes during childhood, so it’s too late to do anything now. Where it is true that a recent study showed that we get less than 25 percent of our total sun exposure by age 18. it is men over the age of 40 who spend the most time outdoors, and get the highest annual doses of UV rays. And since we’re living longer and spending more time outdoors on the whole, preventing skin damage should be an important part of a healthy lifestyle.



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