Sunscreen 101

See that shot glass? BURN that image into your memory, because believe it or not, that's how much you should use every time you apply sunscreen! What else do you need to know? Here's my Sunscreen 101.

Let's start with SPF. What does it mean? Sun Protection Factor is a measure of a sunscreen's ability to protect the wearer against UV radiation from UVB. Note that the sun produces both UVA and UVB, and BOTH cause damage that can lead to skin cancers. Right now, though, the SPF only addresses the UVB protection. So, SPF means that compared to bare skin, the sunscreen keeps you from burning X times longer. If it takes you a half hour to turn red with bare skin, a sunscreen with an SPF of 30 should in theory keep you from burning 30 times longer, which would be 900 minutes- 15 hours. Unfortunately, no sunscreen stays fully effective beyond two hours without re-application. Additionally, sunscreens with an SPF of 15 block roughly 93% of UVB rays, SPF 30 ~ 97%, and SPF 50 is 98%. Therefore, even with perfect application, no sunscreen blocks all UVB rays, and many block no UVA rays.

How much should you use to be effective? See above- an OUNCE of prevention here for sure, and that same amount should be REAPPLIED every two hours. This means you will use roughly half of an 8 ounce bottle on ONE PERSON during a full day outdoors. (And no, I don't own stock or have financial interests in sunscreens.)

Which ingredients are important? Most dermatologists recommend combining the physical barrier ingredients that protect against the deep penetrating UVA rays, such as ZINC OXIDE and TITANIUM DIOXIDE (the ones that leave the white residue) along with the chemical barrier agents known to block UVBs, such as PABA, salicylates, cinnamates and benzophenones. Since nearly all sunscreens contain mixes of the chemical barriers, I scan the ingredients to be sure it also contains zinc oxide or titanium dioxide. Note that some people are sensitive to PABA or other ingredients, and may do best with purely barrier sunscreens and clothing (such as surf shirts.) Ask your doctor for more specifics if you are concerned about allergens.

Easy Sprays...NOT my first choice. Why? Few have either zinc oxide or titanium dioxide, and those that do are very expensive and have these minerals broken down into "nanoparticles" to allow them to be in a light enough liquid to spray. In the medical literature, some debate exists as to whether these nano-sized minerals can potentially cause cancer, which is of course, the opposite of our intent. Regardless of these issues, probably the biggest issue with sprays is that people use TINY portions- picture that less than 10 second total body spray- and so they are not obtaining anywhere near the listed SPF. Would I prefer that over skipping sunscreen all together? Yes...which means I do keep some on hand.

What do I usually buy? Our family's current favorites are Banana Boat's Sport or "Baby" lotions. To sunscreen's credit, my kids complain that their skin is "way too white" because I never let them tan. I take that as a compliment! Probably more importantly, for extended sun exposure we all use swim shirts, and try to consistently wear hats and sunglasses.

BOTTOM LINE: Get a sunscreen that contains both chemical and barrier agents (think titanium dioxide) and realize an 8 oz tube should be used up by a family of four in ONE morning OR afternoon since each person needs ONE OZ every TWO HOURS.