An SPF of 30 means that technically, you could be out in the sun 30 times longer before you get sunburned than you would be able to if you went out without sunscreen, as long as you keep reapplying it appropriately.
防晒系数30意味着,理论上你在户外被太阳晒伤的时间是你没涂防晒被晒伤的时间的30倍,前提是你一直适当补涂。
例如:在不涂防晒产品的情况下,在阳光下停留20分钟后,你的皮肤会稍稍变成淡红色,则防晒系数30的产品可保护你达10小时之久。
20(分钟)*30(SPF)=600分钟(10小时)
防晒系数并不是直接反应对紫外线的抵挡能力,而且还不是一个线性关系的指标,所以防晒系数并非越高越好。相反,防晒系数越高的防晒霜使用起来越油腻、厚重、不舒适。
According to Kundu, SPF 15 filters about 93% of UVB rays; SPF 30 filters about 97% of UVB rays; and SPF 50 filters about 98% of UVB rays. The difference between SPF 30 and SPF 50 is only a 1% filtering improvement, she says, and since SPF 30 is readily available at many different price points, that’s the one many dermatologists recommend.
据昆都称,防晒系数15可过滤约93%的中波紫外线,防晒系数30可过滤约97%的中波紫外线,而防晒系数50可过滤约98%的中波紫外线。防晒系数30和50之间的防护能力仅相差1%。昆都称,因为防晒系数30的防晒霜有许多价格可供选择,所以受到许多皮肤科医生推荐。
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2020-09-15
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