Photo: Jupiterimages/Goodshoot/Getty Images
Spend too much time in the sun and you'll end up with a nasty burn -- especially if you're light-skinned. Getting too many rays also means you'll get old and wrinkly faster, and you might end up with skin cancer. To keep that from happening, skip the tanning oil and slather on the sunscreen. But you have to pick the right SPF.
SPF stands for sun protection factor or skin protection factor. That little number tells you how long you can stay out in the sun without getting burned by UVB rays -- medium-length ultraviolet rays that burn skin cells. If your sunscreen's rated for SPF 20, you can stay out 20 times longer than you can with no protection at all. The higher the number, the better the sunscreen's going to do.
Of course, there's more than one kind of sunscreen out there. The most basic ones just block UV-B rays and keep you from getting burned. Sunscreens with oxybenzone, avobenzone or mexoryl in them also stop UVA rays -- the same rays as black light. UVA rays can age your skin and give you wrinkles early. Just make sure you know your chemicals. Some ingredients in regular sunscreen can hurt frogs and fish when they get into the water, or give some people an allergic reaction. If you want to avoid these chemicals, try a sunblock instead. Sunblock has tiny particles of zinc oxide or titanium dioxide in it, and blocks both UVA and UVB rays. The downsides are that sunblock costs a lot more and can be a real pain to put on.
Putting It On
Even if you get the highest SPF sunscreen out there, you have to put it on more than once. The American Academy of Dermatology says to put on sunscreen 30 minutes before you go outside, to give it time to work. Smear on some more every two hours, even if you're using the kind that doesn't wash off in water. If you get in the pool or get all sweaty, put on new sunscreen right afterward. Make sure you use plenty of sunscreen at once and get it on in an even layer, but don't get that stuff near your eyes. Stick to a pair of sunglasses with UV protection, instead.
You might think it's smart to buy the highest SPF sunscreen they make, but that's not such a great idea. Nobody wants to get exposed to more chemicals than they have to. Plus, high-SPF products are pricey. Stick to the lowest SPF you can use without getting a burn. Of course, if you or somebody in your family has had skin cancer, or if you already have sun sensitivity, you're going to need a stronger product. Don't forget that little kids need more sunscreen than adults. Just don't put any on the babies -- they need to wear a cover-up or just to play in the shade, since sunscreen can be bad for their health.