Indeed, as Dr. Wang also pointed out, when people opt for increased SPFs, they may actually feel so protected by the product that they ultimately neglect proper sun protection. “When people use really high SPF products, they tend not to reapply, they tend to stay out in the sun much longer, and they don’t use other protective modalities such as clothing and hats,” he says. Regardless of any increase in protection that a high SPF may or may not offer, one thing is certain: It doesn’t give your body a free pass from sunburns, aging, or cancers, and it doesn’t protect you from those things for any greater length of time than the lower SPF options. Both Dr. Wang and Dr. Gohara emphasized that, no matter what the SPF, it’s crucial to reapply your sunscreen every two hours.
　　事实上，Wang博士也指出，当人们选择高SPF值的防晒霜时，他们就觉得很有安全感，从而忽略了必要的防晒措施。“当使用高SPF防晒产品时，人们一般就不会补擦，而且经常在太阳底下待很长时间，也不采取其他的防晒措施，诸如穿防晒服，戴防晒帽等。”不论高SPF的防晒霜是否在隔绝紫外线能力上有所加强，有一件事是肯定的，即它们无法完全避免晒伤，皮肤老化或者皮肤癌。而且它们也不会比其他低SPF值得防晒霜防晒效果更持久。Wang博士和Gohara博士都强调，无论防晒霜的SPF值是多少，一定要每隔两小时补擦。

　　Which brings us to what is potentially the most important factor of the SPF conversation: Human error. True, an SPF 30 sunscreen technically blocks about 95% of UVB rays, but that’s only when it’s used correctly — and it’s usually not. “Most people don’t use enough sunscreen, so the real SPF protection they’re getting is about one third of the labeled SPF,” Dr. Wang says. “So, if you have a product that says [SPF] 60, you’re really getting an SPF of maybe 20 or 30.” Though there’s plenty of available information on how to properly apply sunscreen — including instructions on the bottles themselves — most of us simply don’t lather on as much product as is used in testing and labeling SPFs. On top of that, we miss spots, we forget to reapply, we go in the water too soon, and we don’t compensate for these errors with supplemental protection.
　　这就引申出使用防晒霜一个最关键的方面：人为失误。的确，SPF值为30的防晒霜可以隔绝93％的紫外线，但前提是人们的使用方法必须正确。可是通常人不会正确使用防晒霜。Wang博士指出：“大多数人防晒霜的用量不够，导致使用的防晒霜防晒效果只有实际SPF值得三分之一左右。因此当使用SPF值为60的防晒霜时，真正有用的SPF值仅仅为20或30。”虽然有很多教大家如何正确使用防晒霜的教程，包括防晒霜瓶子上也有，大多数人的涂抹量还是达不到SPF贴标检测过程的用量。除此之外，我们总是会漏涂，忘记补涂，游泳时很快跳下水，而且不知道使用别的防护措施来弥补这些过失。

　　So what does this all mean for your next trip down the sunscreen aisle? It boils down to this: The most important thing is to use a broad-spectrum sunscreen of at least SPF 30 — and to use it often and properly. But, given the fact that none of us is perfect (and certainly not when it comes to applying sunscreen), it just may be worth it to bump that SPF up a notch or two to help make up for that inevitable human error. Just remember that when you do, you should put higher SPF product in your shopping cart. From there on out, it’s (vigilant and careful sunscreen) business as usual.
　　所以这些对你下次涂抹防晒霜有什么启示呢？归根结底：最重要的是使用广谱防晒霜（SPF值大于等于30），并且要学会合理且频繁的使用。但是，人无完人（尤其是谈到使用防晒霜时），我们不妨每次多用一点点来弥补那些人为失误。记住尽可能购买高SPF值的防晒霜，这以后就是正常的防晒工作了。（爱语吧）