Q. Whats the Difference Between a Sunscreen and a Sunblock?

    Sunscreens are the most popular at the moment. Available in creams, lotions and gels, they contain chemicals that absorb UV rays. They are also inconspicous on the skin. The chemicals that are most often found in sunscreens include PABA, Benzophenones, Cinnamates, Salicylates,

    Sunblocks instead of absorbing UV rays, reflect them. At one time sunblocks could be spotted by the opaque white film, but new technology has created sunblocks with particles so tiny, that the opaque film in no longer noticeable. Chemicals most common in sunblocks include Titanium dioxide and zinc oxide.

    據(jù)國(guó)際合眾社消息 美國(guó)一項(xiàng)報(bào)告說，多數(shù)人不清楚防曬乳和遮光劑的區(qū)別。

    哈佛醫(yī)學(xué)院一項(xiàng)研究解釋，防曬乳反射陽光，因此阻止光線到達(dá)皮膚；遮光劑吸收紫外線要多于反射紫外線。

    防曬乳比如氧化鋅，二氧化鈦，能有效保護(hù)皮膚免受UVA 和UVB傷害，這兩種紫外線能導(dǎo)致曬傷和皮膚癌。

    防曬乳在皮膚上呈白色，而遮光劑一般無色。遮光劑的主要缺點(diǎn)是在日光照射幾個(gè)小時(shí)以后就分解了，需要重新涂抹。

    美國(guó)皮膚病學(xué)會(huì)建議使用SPF值低于15的遮光劑，但如果皮膚特別好，或者患皮膚癌的幾率比較高，可以選擇SPF值更大的遮光劑。SPF值越大，保護(hù)的時(shí)間越長(zhǎng)。

    報(bào)告說，貼有廣譜標(biāo)簽的產(chǎn)品一般含有多種防曬成份，對(duì)不同波長(zhǎng)紫外線都有保護(hù)作用。