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| 7.28.09 | ||
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| WHAT IS SPF? | ||
SPF, or sunburn protection factor, measures how much UV radiation is required to produce sunburn on protected skin relative to the amount required to produce sunburn on unprotected skin. SPF is not directly related to time of solar exposure but to amount of exposure. If you normally get a sunburn in one hour, an SPF 15 does not allow you to stay in the sun 15 hours. SPF 15 actually blocks only about 93 percent of the UVB (ultraviolet B) rays that cause sunburns. SPF 30 absorbs nearly 97 percent and SPF 50, 98 percent. |
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| Sun-protective clothing is identified by UPF (ultraviolet protection factor) rather than SPF. | ||
| The American Academy of Dermatologists recommends using a broad-spectrum sunscreen of at least SPF 15. The group notes, however, that sunscreens are not perfect and that "there is no 'safe' ultraviolet (UV) light, and there is no such thing as a safe tan." | ||
| SOURCES www.fda.gov, www.aad.org, Dallas Morning News files | ||