Time for SPF's Fall and Winter Too!
W
e all know we should use spf’s. But how many of us un- derstand what SPF”s are? Sun
Protection Factor, measures the length of time a product protects against skin reddening from UVB, compared to how long the skin takes to redden without protection. If it takes 20 minutes without protection to begin reddening, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer—about 5 hours. (Actually, it may take up to 24 hours after sun exposure for redness to become visible.) To maintain the SPF, reapply sunscreen every two hours and right after swimming. The Skin Cancer Foundation recom-
mends SPFs of at least 15, which block 93 percent of UVB. While SPFs higher than 30 block only 4 percent more UVB, they may be advisable for sun-sensitive indi- viduals, skin cancer patients, and people at high risk of developing skin cancer. They also allow some margin for error if too little sunscreen is applied. While SPF is the universal measure-
ment of UVB protection, no comparable standard exists for UVA. Scientists world- wide are working to develop a standard- ized testing and certification method to measure UVA protection. Broad-spectrum protection: The
phrase indicates that a product shields against UVA as well as UVB. It does not guarantee protection against all UVA wavelengths, however. Most broad-spec- trum sunscreens and sun blocks with an SPF of 15 or higher do a good job against UVB and short UVA rays; if they
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