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Skin Care

What does the spf number of sunscreen lotions mean?

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07/02/2014

There are two categories of UV light -- UVA and UVB -- that we consider in terms of sunscreen. UVB causes sunburn, and UVA has more long-term damaging effects on the skin, like premature aging. SPF, or sun protection factor, numbers were introduced in 1962 to measure a sunscreen's effect against UVB rays.