那年军训，学姐让我防晒我没听，结果……(2)

Protective grade of sunscreen is often leveled as PA+, PA++, PA+++ with the more plus sign the more protection from UVA rays.

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PA指数中，防晒等级通常分为PA+、PA++、PA+++，后面的+号越多，表明抵御UVA射线的能力越强。

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不过专家也表示，PA系数高的产品往往含有大量物理或化学防晒剂，对皮肤的刺激较大一些，容易堵塞毛孔，甚至滋生暗疮和粉刺，要谨慎选用哦。

选择防晒霜最重要的一点就是选择合适的防晒系数。

When going in and out of the sun on a daily basis, for instance going to and from work, your skin gets exposed to a lot of ultraviolet (UV) rays. Using a sunscreen with an SPF of at least 15 every day will help protect you from this type of quick, daily exposure.

当你每天进出有日照的环境，例如上下班时，你的皮肤会暴露在大量的紫外线下。每天使用防晒系数至少为15的防晒霜可以帮助你抵御这种快速的日常紫外线照射。

If you plan on spending time outdoors, such as going to the beach or playing a sports game outside, it's important to give your skin more protection. Pick a sunscreen that has a SPF between 30 and 70.

如果你打算花时间在户外，如去海滩或在户外玩体育游戏，那就需要加倍保护你的皮肤了。请选择防晒系数在30到70之间的防晒霜。

Sunscreen with an SPF higher than 70 is generally only slightly better than SPF 50-70. Picking a sunscreen with a SPF of 80 or 90 may just cause you to spend extra money for a product that is really no better.

防晒系数高于70的防晒霜通常只比防晒系数在50到70之间的效果好一点点。所以选择防晒系数为80或90的防晒霜性价比并不高。

当然，只有在正确使用防晒霜的情况下，防晒霜才能达到相应防晒指数的效果。

据美国皮肤病学会称，一盎司的防晒霜，被认为是覆盖身体暴露区域所需的量，也就是差不多一个小玻璃杯的量。

关于时间，建议在出门前15分钟涂抹防晒霜。

另外，要注意多次补涂防晒霜。美国皮肤病学会建议大约每两个小时重新涂抹一次防晒霜。

In addition, the FDA recommends that sunscreen not be worn by infants younger than 6 months, suggesting instead that they be kept in the shade and avoid sun exposure from 10 a.m. to 2 p.m., when UV rays are at their strongest.

此外，美国食品和药物管理局建议，6个月以下的婴儿不要使用防晒霜，而应让他们待在阴凉处，并避免在上午10点至下午2点接受阳光照射，因为这段时间里紫外线最强。

虽然上面介绍了这么多防晒霜知识，但最佳的防晒方法，并不是只抹防晒霜。