By Chris Woolston

Q What’s the best sunscreen to protect my skin from cancer?
A Throw out that half-full bottle of sunscreen from last summer, says Leslie Baumann, M.D., a spokesperson for the Skin Cancer Foundation. Many products made in the dark ages of mid-2006 or before don’t offer sufficient protection against the ultraviolet rays that cause skin cancer.

Most older sunscreens block out UVB rays, which cause sunburns, but they often don’t protect against UVA, which ages skin. Both kinds of ultraviolet have been implicated in the three types of skin cancer: the highly treatable basal cell and squamous cell and the more serious melanoma. An SPF score is a measure of protection against UVB

You can protect your skin with high-SPF sunscreens that contain new UVA-blocking ingredients such as Helioplex (used in Neutrogena sunscreens) or stabilized avobenzone (try Skin Effects). Baumann also suggests Aveeno Continuous Protection and sunscreens from the European company La Roche- Posay. Sunblocks containing titanium dioxide or zinc oxide are also good; these natural minerals are now available in sheer creams so you won’t have lifeguard nose.

Sunscreens work only when used properly. You should apply a generous amount—a dime-size splash for your face—30 minutes before going outside. Reapply every two hours. For more tips, go to www.skincancer.org.