Sunscreen - What You Don't Know Can Hurt You

If you're prone to sunburn you're probably very familiar with sunscreen and the SPF (sun protection factor) number. But when it comes to sunscreen, there's a lot more to consider than that one number. Here's some new or relatively unknown information that may help you do a better job of protecting your skin from not only sunburn, but also wrinkles and skin cancer.

You may know that there are two types of ultraviolet (UV) rays - UV-A and UV-B. Many bottles of sunscreen mention both types. But until now, the FDA has regulated only the UV-B protection factor. That's great if you want to avoid getting burned. But it's the UV-A rays that cause wrinkles, and even more importantly, have been linked to skin cancer.

The FDA is planning to issue new rules soon that will require an update of the SPF rating on the label of all bottles of sunscreen. Once these new rules take effect, there will be two ratings - one for UV-A and one for UV-B.

Here are a few other things you may not have known:

Most people don't use enough sunscreen. Either they don't apply enough to begin with, or they don't apply it frequently enough. The recommendation for adults is a shot glassful and for children a tablespoonful (although this probably depends on the size of the child). Also, you may have known that sunscreen needs to be reapplied after swimming or bathing, but did you know you should reapply it every two hours even if you don't get wet?

Sunscreen doesn't start to work right away. It should really be applied about a half hour before you plan to go out in the sun - not right before.

Surfaces that reflect a lot of light - like white sand, snow, and water - can be more damaging because they can "bounce" UV rays back up. That explains why you can get sunburned when you're skiing - and why you need to be very careful to protect yourself on rafting trips.

UV exposure varies not only by factors like the time of year, the altitude, and the cloud cover, but also by location. The UV index is a measure of how dangerous UV rays may be in a particular location. This EPA site has a map that shows the UV index across the United States. But you can also get the index for a specific location by entering a ZIP code or city name into a search box further down the page.

Most wrinkles aren't caused by dry skin - they're the result of overexposure to UV-A rays.

UV rays are at their strongest between the hours of 10 am and 4 pm. You'll get less exposure if you go outside at other times.

Sunscreen can be a lifesaver - literally - and the FDA is working toward making it even more useful by regulating the UV-A protection factor. But in the meantime you can help protect yourself by considering not only the SPF but also how much sunscreen you use - and when and how often you use it.