Planning some fun in the sun? You don't have to spend big bucks on sunscreens and high SPF levels to get good protection.

    If your sunscreen meets the American Academy of Dermatology's recommendations -- it's water resistant, has an SPF of at least 15, broad-spectrum coverage against UVA and UVB light, the proper ingredients, and you reapply a one-ounce amount frequently -- you should be good to go, even with a cheaper store brand. Some dermatologists recommend using at least SPF 30.

    One thing to watch out for is UVA-ray protection since SPF only applies to UVB rays, says Henry Lim, chairman of the department of dermatology at Henry Ford Hospital in Detroit.

    The Food and Drug Administration doesn't have a UVA rating yet, he says, so while sunscreens may claim broad-spectrum protection, you may not be getting strong protection from UVA rays. He suggests using products containing avobenzone （also called Parsol 1789）, titanium dioxide or zinc oxide.

    As for SPF 100? If you're outdoors on a sunny day, "SPF 50 is probably sufficient," says Dr. Lim. "Beyond 30, the increase in the filtering is small."

    SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97%, and protection doesn't increase proportionately with a higher SPF number, according to the American Academy of Dermatology （aad.org）.

    想要在戶外活動嗎？你不必為了獲得好的防護效果而花很多錢在防曬品和高的防曬系數(shù)上。

    如果你的防曬品和美國皮膚醫(yī)學研究院所推薦的一樣，防曬系數(shù)最少在15以上、能夠同時地域uva和uvb兩種紫外線、成分適當并且你能夠頻繁涂抹，那么你就可以盡情的享受戶外活動，即便它不是什么大品牌。皮膚專家大多推薦防曬系數(shù)在30以上的防曬品。

    uva即生活紫外線的防護是需要注意的，因為防曬系數(shù)僅僅適用于uvb即戶外紫外線的防護，底特律州亨利福特醫(yī)院的皮膚科主任亨利。李這樣說道。他指出，食品和藥物管理部門還沒有uva的評定等級，因此當防曬品要求有比較廣泛用途時，它就可能對uva的防護作用很小。他建議選擇含有一種叫作阿伏苯宗或者巴松1789的物質(zhì)，和鈦的二氧化物或者鋅的氧化物的成分的防曬產(chǎn)品。

    對于防曬系數(shù)100的呢？如果你的戶外活動是在晴天，"防曬系數(shù)50就非常適當了，"李醫(yī)生說。"防曬系數(shù)超過30,過濾紫外線功效方面的增益就很小了。"