SPF stands for Sun Protection Factor—the key metric for a sunscreen's effectiveness against sunburn. It measures protection from UVB rays based on the European standard: 2 mg of product per cm² of skin, reapplied every two hours. While focused on UVB, regulations ensure at least one-third of the SPF value covers UVA rays too.
Numbers like 20, 30, 50, or 50+ indicate UVB blockage: SPF 20 filters ~92%, 30 ~95%, and 50 ~98%. Before 2006, higher ratings like 60 or 100 existed in the EU, but they confused consumers into thinking they meant full-day, 100% protection. No sunscreen is total—reapply often, even indoors near windows. Regulated standards mean SPF 30 delivers consistent protection across brands and textures.
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