From the Skin Cancer Foundation:
What Is SPF?
Most sunscreens with an SPF of 15 or higher do an excellent job of protecting against UVB. SPF — or Sun Protection Factor — is a measure of a sunscreen's ability to prevent UVB from damaging the skin. Here's how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about five hours.
How much sunscreen should I use and how often should I put it on?
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 be reapplied immediately after swimming, toweling off, or sweating a great deal.
Do moisturizers, tinted foundation, lipstick and other cosmetics containing an SPF 15 sunscreen provide as much protection as sunscreen used alone?
The cosmetics neither increase nor decrease the photoprotective value of the sunscreen. They have the great advantage that most women apply them every day. Some products for men also combine moisturizer and sunscreen. It's important, however, to use a separate sunscreen or reapply the cosmetics every two hours when outside.
For the best results, if you are using a moisturizer and a separate sunscreen, the moisturizer should go on first, then sunscreen, then makeup. If you are also using a topical medication, that should be applied before everything else, then the rest of the layering process is repeated.
Here are some popular makeup products which have earned The Skin Cancer Foundation Seal of Recommendation:
Bare Escentuals i.d. Bare Minerals Bare Escentuals i.d. bareMinerals SPF Foundation SPF 15 Bare Escentuals i.d. Bare Minerals Bare Escentuals i.d. bareMinerals Summer Bisque Multi-Tasking Minerals SPF 20 Colorescience Colorescience Suncanny Foundation Brush SPF 20 Jafra Cosmetics International Jafra Skin Defense Makeup SPF 15 Jafra Cosmetics International Jafra 2 in 1 Powder Makeup SPF 15 Jafra Cosmetics International Jafra Mineral Makeup SPF 15 L'Oreal Paris L'Oreal Paris Bare Naturale Foundation SPF 19 L'Oreal Paris L'Oreal Paris Bare Naturale Gentle Mineral Powder SPF 24 Physicians Formula Physicians Formula Le Velvet Film Makeup SPF 15 (Cream) Physicians Formula Physicians Formula Mineral Wear Talc-Free Mineral Pressed Powder SPF 16 Physicians Formula Physicians Formula Mineral Wear Talc Free Mineral Loose Powder SPF 16 Physicians Formula Physicians Formula Mineral Wear Talc Free Mineral Concealer Stick SPF 15 Physicians Formula Physicians Formula Mineral Wear Talc Free Mineral Foundation SPF 15 Shiseido Cosmetics Shiseido The Makeup Brightening Veil SPF 24 Shiseido Cosmetics Shiseido The Makeup Matifying Veil SPF 17 Shiseido Cosmetics Shiseido The Makeup Smoothing Veil SPF 16 Shiseido Cosmetics Shiseido Sun Protection Compact Foundation SPF 34 Shiseido Cosmetics Shiseido Sun Protection Liquid Foundation SPF 42 Shiseido Cosmetics Shiseido Sun Protection Stick Foundation SPF 35 Shiseido Cosmetics Shiseido The Makeup Lifting Foundation SPF 16 Shiseido Cosmetics Shiseido White Lucent Brightening Powder Foundation SPF 24 Shiseido Cosmetics Shiseido The Makeup - Dual Balancing Foundation SPF 17 Shiseido Cosmetics Cle De Peau Beaute Refining Fluid Foundation SPF 24
Common myths
Wearing sunscreen can cause vitamin D deficiency.
There is some controversy regarding this issue, but few dermatologists believe (and no studies have shown) that sunscreens cause vitamin D deficiency. Also, vitamin D is available in dietary supplements and foods such as salmon and eggs, as well as enriched milk and orange juice.If it's cold or cloudy outside, you don't need sunscreen.
This is not true. Up to 40 percent of the sun's ultraviolet radiation reaches the earth on a completely cloudy day. This misperception often leads to the most serious sunburns, because people spend all day outdoors with no protection from the sun.80 percent of your sun exposure comes as a child, so it's too late to do anything now.
It appears that this universally promoted idea was based largely on a misinterpretation. A recent multi-center study showed that we get less than 25 percent of our total sun exposure by age 18. In fact, 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 adult Americans are living longer and spending more leisure time outdoors, preventing ongoing skin damage will continue to be an important part of a healthy lifestyle.
