But what's in there?

不過成份有什麼？

And is it true that they kill 99.99% of germs?

是不是真的可以殺死 99.99% 的細菌？

Most popular hand sanitizers are alcohol-based.

大部分市面上的乾洗手都含有酒精。

The active ingredient is around 70% alcohol, depending on the formulation.

其中的活性成份為濃度 70% 的酒精，視配方而異。

The alcohol can be either ethanol, which is the same stuff that's in your booze; isopropanol, the stuff in rubbing alcohol; or n-propanol, rubbing alcohol's chemical sibling.

其中會使用的酒精是乙醇，是在你的酒單裡可以找到的成份；另一種是異丙醇，是一種醫用酒精；還有一種是正丙醇，與醫用酒精屬同一個家族。

They all pretty much work the same way though, which is by dissolving the outer coats of bacteria and viruses and basically exploding them.

這些酒精的作用基本上差不多，可以溶解細菌和病菌外層的細胞膜，使它們爆破。

Alcohol is polar, with water-loving hydroxyl groups.

酒精是極性的，帶有親水的羥基。

And it loves to disrupt the protein and lipid molecules that make up both bacterial membranes and viral envelopes.

酒精會破壞細菌膜和病毒包膜上的蛋白質和脂質分子。

When those all-important outer coats fall apart, these disease-causing culprits literally spill their guts all over the place, leaving them in no position to make anyone sick.

一旦包覆著重要分子的外膜崩塌，病毒禍源的細胞內容物就會流出，使它無法引起人類生病。

But what about people who never touch hand sanitizer because it will breed unkillable super-germs that will kill us all?

不過那些從來都不使用乾洗手因為覺得會滋生出超級細菌來消滅我們的人怎麼辦呢？

That's a valid concern with antibiotics, which are chemicals that target some point in a bacterium's life cycle.

抗菌素有一個問題，抗菌素只是可以針對對付細菌生命週期中某些特點的化學物質。

The antibiotics in antimicrobial hand soap can lead to the emergence of bacterial strains that are resistant and harder to kill.

含抗菌劑的肥皂裡的抗菌素可能會出現病菌菌株導致產生抵抗性，變得更難殺死細菌。

But resistance isn't really a problem with alcohol-based hand sanitizers.

不過這種抵抗性的情況不會出現於酒精乾洗手。

Bacteria can't develop resistance to having their proteins and membranes blasted.

細菌的蛋白質和細胞膜爆破後，無法產生抵抗性。

So these alcohol-based hand rubs aren't going to stop working.

而酒精乾洗手是不會因此而停止運作。

Make sure they are alcohol-based, though, some contain antibiotics instead of alcohol, and those do carry the risk of resistance.

要確定你所使用的是含有酒精，因為有的是含有抗生素而非酒精，病毒有機會產生抗藥性。

But alcohol and water alone do not make that goo.

只有酒精和水是不會讓它變得黏稠。

It's alcohol that does the germ-murdering, but there's other stuff in there.

只有酒精有殺菌作用，裡面其實還有其他成份。

The biggest one is glycerol.

其中佔最大比例的是甘油。

Glycerol is chemically an alcohol, but unlike its cousins, it's in there not to kill the germs but to give the hand sanitizer its gooey consistency that makes it more portable and easier to use.

甘油在化學上屬酒精類，不過和酒精家族裡不一樣的是它並不是用作殺菌，而是讓乾洗手變得黏稠，好讓乾洗手更方便攜帶和使用。

Otherwise it'd be like pouring vodka on your hands.

不然就像是把伏特加倒到手裡。

Don't pour vodka on your hands, guys, come on.

大家別把伏特加倒在手中，拜託。

But while alcohol is all you need to kill germs, it's not all that goes in there.

不過雖然酒精可以拿來殺菌，乾洗手的成分可不只這樣。

Ethanol and isopropanol can dry your skin.

乙醇和異丙醇會使我們的手變得乾燥。

Glycerol will help counteract that effect, but so do a host of other additives manufacturers might put in.

甘油可以有助緩解這個問題，不過製造商可能會加入大量添加物。

This often includes tocopheryl acetate, a molecule very similar to vitamin E that also happens to be great for your skin, and some familiar stuff like aloe.

通常會加入乙酸生育酚，它的分子結構與維生素 E 相似。這對你的皮膚很好，有點像蘆薈的成份。

A host of colors and fragrances might also go in there.

有的甚至會加入大量色素和香精。

None of those are necessary to make the hand sanitizer work, but they might make your hands smell nice.

這些成份都無助乾洗手起殺菌的作用，不過可以讓你的手聞起來香香的。

Mmm, mmm, mmm!

嗯！

Toasted marshmallow!

烤棉花糖的味道！

Ethanol-based hand sanitizer might also contain bitter or bad-tasting compounds to stop the small percentage of desperate people out there who are willing to drink it because, well, it is alcohol.

含有乙醇的乾洗手會帶有苦味或讓人難以入口的化合物，以防一些想喝酒的人拿去喝。你們知道的，這是酒精嘛！

So we are back to the question: Do these chemical goo recipes really kill 99.99% of germs?

回到我們影片的問題；到底這些化學配方是否能殺死 99.99% 的細菌？

Those numbers are usually the results of lab testing.

這些都是從實驗室出來的數字。

But real life is messier.

現實的狀況更髒。

And the effectiveness of hand sanitizer varies based on how oily or dirty your hands are, how much alcohol is in there, and which germs you're actually talking about.

而且乾洗手的效果視雙手髒污的程度、成份的酒精含量，以及病菌的類型。

Under ideal conditions, some disease-causing germs really do get zapped at that rate, but others don't.

在理想的情況下，有些帶病源的細菌在一定的配方比例下會被破壞，可是有些卻不會。

You should keep in mind, hand sanitizers work best in combination with hand washing regiment, because they don't physically remove dirt and gunk from your hands.

大家要謹記，乾洗手要配合洗手才能發揮最大的功效，因為乾洗手無法洗去手上的灰塵和髒污。

So don't forget that soap and water.

所以別忘記肥皂和水。

Do you always have a bottle of this stuff wherever you go, or you are an alcohol goo-phobe?

你是會帶著這瓶四處跑，或是你是討厭這黏黏稠稠的酒精的人？

Sound off in the comments, and tell us what other everyday chemistry we should cover!

歡迎在下面討論，也可以告訴我們可以討論日常生活中能接觸到的化學物品吧！

Hit that "Like" button, be sure to subscribe and, hey, thanks for watching.

請大家按讚，別忘了追蹤我們的頻道。謝謝大家收看！