Killer Chlorine
If you’ve ever seen movies about World War I, you know that the soldiers in the trenches often wore bulbous gas masks that made them look like human insects. The masks were necessary to protect them from chemical weapons such as chlorine gas, a noxious substance that could almost instantly suffocate unprotected victims.
Pool Pests
If chlorine is so dangerous, why the do we dump it in swimming pools?
As you probably already know, chlorine is used to disinfect swimming pools. It also gives most pools their distinctive odor. Chlorine comes in pellet, liquid, and gas forms, and when it reacts with pool water it immediately breaks down into different chemicals, including hypochlorous acid and hypochlorite ion. Both chemicals attack microorganisms in the water by breaking through their cell walls and scrambling the inner workings of the cells, rendering them harmless.
Parts Per Million
So why don’t these killer chemicals destroy human cells as well? They would, if not for the very small amounts of chlorine needed to cleanse the typical pool. For example, the concentration of chlorine used to sanitize an Olympic-size pool is three parts per million, meaning that for every three molecules of chlorine there are one million water molecules. Such low concentrations may cause slight irritation to the eyes and skin, but there’s not enough chlorine to cause any real harm to swimmers.
Chlorine is not the only chemical used to keep pools clean—bromine and ozone are becoming increasingly popular in pool maintenance facilities. But chlorine is still the pool cleaner’s mainstay.
致命的氯
如果你看過關(guān)于一戰(zhàn)的電影的話，你肯定知道戰(zhàn)壕內(nèi)的士兵們通常會配戴著球莖形狀的防毒面罩，看起來很像人形昆蟲。這種面具可以保護(hù)士兵不被化學(xué)武器攻擊，如氯氣----一種可以快速使人窒息的有毒氣體。
水池里的有害微生物。
如果氯算危險物質(zhì)的話，那么為什么我們要把它倒進(jìn)游泳池里呢？
你可能已經(jīng)知道，氯可以用于消毒游泳池。同時，大多數(shù)加氯的游泳池也會有一種獨特的味道。氯可以以固、液、氣三種形式存在。氯遇到水會立刻分解成不同的化學(xué)物質(zhì)，如：次氯酸和次氯酸鹽離子。這兩種化學(xué)物質(zhì)都可以通過破壞水中微生物的細(xì)胞壁、擾亂細(xì)胞內(nèi)部正常運轉(zhuǎn)而使微生物變的無害。
氯濃度
那這些致命的化學(xué)物質(zhì)不會破壞人體細(xì)胞呢？如果用于清理泳池的氯使用量過大的話是會對人體造成傷害的。比如，用于奧運會的泳池消毒的氯濃度是3比100萬，也就是說每一百萬個水分子里有三個氯分子。這樣的低濃度可能只會對眼睛和皮膚產(chǎn)生輕微刺激，但對游泳的人來說不會產(chǎn)生真正的傷害。
氯不是能夠保持泳池清潔的化學(xué)物質(zhì)---溴和臭氧在泳池的日常維護(hù)中也越加頻繁。但泳池清潔人員主要還是用氯來消毒。
