炎炎夏日渐渐逼近，你的防晒工作做好了吗？很多妹子都知道要涂防晒霜，不过你知道防晒霜到底应该怎么涂吗？
来听听专家怎么说。

 防晒霜你涂对了吗？夏日防晒大作战，你必须知道的tips
炎炎夏日渐渐逼近，你的防晒工作做好了吗？很多妹子都知道要涂防晒霜，不过你知道防晒霜到底应该怎么涂吗？
来听听专家怎么说。

 
明星们这样用“呲_”

    Skin experts say we should be more careful to check we're protected before sunning ourselves.
皮肤专家说，我们在日晒之前应该更谨慎地确认自己是否做好了防晒工作。

"Applying liberally half an hour before going out into the sun, and then again shortly after going outside, is vital to ensure that you are fully covered and that the sunscreen has had time to be absorbed into the skin," said BAD's Johnathon Major.
英国皮肤科医学会的乔纳森•马杰说：“在日晒之前半小时大量地涂抹防晒霜，然后在出门后不久再涂一次防晒霜，这可以确保防晒霜的全面覆盖，而且皮肤也有时间去吸收防晒霜。

至少每隔两小时就要补涂一次防晒霜

"It should then be reapplied at least every two hours, as the protective filters can break down over time.
“然后至少每隔两小时就要补涂一次防晒霜。因为防晒霜在皮肤上形成的保护层随着时间流逝会逐渐被分解掉。

"It should also be reapplied after any activity where it might be accidentally removed, such as swimming. Water-resistant sunscreens are not friction-resistant, and therefore they can be accidentally removed if you towel dry after swimming or sweating."
“在有可能将防晒霜不小心擦掉的活动之后也应该进行补涂，比如游泳。防水防晒霜并不抗摩擦，所以在你游完泳或流汗后用毛巾擦身子的时候防晒霜可能在无意间被擦掉。

Although getting a tan looks great, prolonged exposure can increase the risk of developing melanoma - the deadliest form of skin cancer.
尽管古铜色的皮肤看起来很棒，但是长时间暴露在日光下会增加患黑色素瘤的风险，这是最致命的一种皮肤癌。

    As sunscreen ages, its sun-protection ingredients degrade, reducing its effectiveness.
防晒霜老化后，防晒成分的纯度会降低，导致防晒效果变差。

"Sunscreens are designed to last for three years," says the assistant professor of dermatology at Cornell University’s Weill graduate school of medicine.
“防晒霜一般都有三年的保质期，” 康奈尔大学威尔医学院皮肤医学科副教授莎莉•李普诺医生指出。

"If your bottle does not have a date printed on it, write the date that you purchased it [on the bottle] and make sure to discard after three years."
“如果防晒霜瓶子上没有印有保质期，那么就在这瓶防晒霜上写上购买日期，确保满三年后不再使用。”

And if you do end up with a sunburn this summer, don’t freak out. There are ways to treat it and reduce its more insufferable side effects.
如果这个夏天你被晒伤了，那也别慌张，这里有一些方法能够减轻痛苦难忍的副作用。

 晒伤了

First, get out of the sun as soon as possible. Then, take a cool shower or bath, and apply cool compresses to any burned or red areas for 10-15 minutes, four times a day.
首先赶紧躲避日晒，然后冲一个冷水澡或洗冷水浴，紧接着在晒伤或晒红处进行10至15分钟的冷敷，每天四次。

"Aloe vera and moisturizer are soothing and will help the skin heal faster," she says. And you can take ibuprofen to help with swelling. "If it blisters, never pop the blisters. Let them heal on their own to avoid infections."
“涂抹芦荟和润肤膏能缓解疼痛，帮助皮肤尽快愈合，”她说。另外，可以服用布洛芬抗肿胀。“如果起了水泡，千万不要挤破，让它们自己慢慢愈合以免感染。”

防晒小知识 tips
▌UV radiation 紫外线辐射
紫外线主要包含两种射线：
?波长较长的UVA（长波黑斑效应紫外线）可以穿透皮肤导致细胞损伤，就是它害你胶原（collagen [?k?l?d??n]）流失，皮肤变老的。
?而波长较短的UVB（中波红斑效应紫外线）则影响皮肤表层，主要会导致皮肤发红（reddening）和晒伤（sunburn）。

 UV radiation 紫外线辐射

▌PA (Protection UVA) UVA保护数值
PA值代表有效防护的时间：
?PA+ 大约4小时，表示有效
?PA++ 大约8小时，表示特别有效
?PA+++ 强力防护，表示非常有效
▌SPF（Sun Protection Factor）防晒系数
SPF也就是皮肤抵挡紫外线的时间倍数。
如果你晒了10分钟太阳，皮肤就开始泛红，那么你用SPF 15的防晒霜，就可以保证你在150分钟内（15x10分钟）不被晒黑。
所以SPF值越大，防晒霜的防晒有效时间就越长。

SPF值