SPF numbers indicate the length of time one can spend in the sun without risk of burning. When using a SPF 15 sunscreen , a fair-skinned person who normally sunburns in 20 minutes of midday sun exposure may tolerate 15 times 20 minutes …
SPF numbers indicate the length of time one can spend in the sun without risk of burning. When using a SPF 15 sunscreen , a fair-skinned person who normally sunburns in 20 minutes of midday sun exposure may tolerate 15 times 20 minutes …
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