你洗手的方式是错的吗?
Now wash your hands! It sounds straightforward, but it isn’t. Although there’s plenty of evidence that washing your hands after you’ve been to the loo, before eating, or after travelling on public transport can reduce the spread of disease, only 5% of people wash their hands properly all the time.
洗手这件事看似简单,其实不然。有很多证据证实,在如厕、吃饭或乘坐公交地铁后洗手能够降低感染疾病的几率。但是,能够每天以正确方式洗手的人只有5%。
An observational study of more than 3,000 people found 10% left public toilets without washing them at all and even if they did, 33% didn’t use soap. This matters because, unfortunately, we can’t resist touching our faces, allowing germs to spread nicely from our hands to our noses and mouths, where they can get into the body. Researchers in Brazil and the US found that we touch surfaces in public spaces an average of 3.3 times an hour and we touch our mouths or noses about 3.6 times an hour.
一项针对3,000多人的调查发现,有10%的人使用公共厕所后没有洗手,而在那些洗了手的人中,则有多达33%的人没用肥皂。我们每天都会用手接触自己的脸,从而让病菌从手上转移到鼻子和嘴上并最终进入人体。巴西和美国的研究人员发现,在公共空间,我们平均每小时会接触各类物体3.3次,而每小时我们会接触自己的嘴或鼻子3.6次。
So it’s clear that we need to wash our hands properly. The problem is there are plenty of myths out there about how to do it.
很显然,我们应当以正确方式洗手。问题在于,坊间流传的很多洗手小贴士都是错的。
Does the water need to be hot to get your hands clean?
热水洗手才干净吗?
In a survey of 500 adults in the US, 69% believed that the temperature of the water has an impact on the effectiveness of handwashing. It is true that heat can kill bacteria (which is why we need to make sure certain foods are piping hot when we eat them), but the water would need to be scalding for this to happen on your skin. Salmonella, for example, can survive temperatures of 55C for more than 10 minutes. If you washed your hands in water this hot you would have serious burns before 30 seconds were up.
一项针对500名美国成年人士的调查发现,有69%的人认为水温会对洗手效果产生影响。热量能够杀灭细菌,这是对的(这就是我们需要吃热食的原因),然而要想达到能够杀灭皮肤细菌的水平,水就必须滚烫才行。例如,沙门氏菌能够在55摄氏度的环境下生存10分钟以上。你要是用这么热的水洗手,用不了30秒,你的皮肤就会严重烫伤。
To find out exactly how many microbes remain on our hands after washing in water ranging in temperature from 4.4C to 50C (39.9F to 122F), researchers in Florida used a method known as the glove-juice technique (though it’s not a juice you’d want to drink). Volunteers’ hands were wiped with a bacterial soup or with raw minced beef. Then their hands were washed in water of a certain temperature before they put on latex gloves and a special solution was poured into the gloves. After a minute of hand massage through the glove to make sure all those bacteria got into the liquid, the glove juice was collected using a pipette, ready for testing in the lab. They found that whether the water was cold, hot or middling made no statistically significant difference to the quantity of bacteria remaining on people’s hands.
为了了解用不同水温的水洗手后手上残留的微生物数量,佛罗里达州的研究人员采用了一种名为“手套-果汁技术”的手段(这里的果汁不是能喝的那种)。实验中,先用生牛肉末擦志愿者的手,然后用不同温度的水洗手。志愿者然后戴上乳胶手套,用一种特殊溶液灌到手套里。志愿者用一分钟的时间按摩双手,以确保手上残留细菌完全进入溶液,然后用吸液管采集手套内溶液,在实验室里进行检测。研究者发现,无论用冷水、热水还是温水洗手,手上残留的细菌数量都没有显著差异。
But before the hot taps are ripped out of public toilets, we shouldn’t forget the vagaries of human behaviour. In these experiments the hand washing was carefully timed, but in real life if the water is very hot or very cold, then we tend not to wash our hands for long. Just showing our hands the water isn’t enough, and some nice warm water might encourage us to tarry a while by the wash basin.
然而,要是我们由此而在公共厕所里取消热水龙头,恐怕并非一个好主意。要知道,人类行为是很奇特的。在上述实验中,受试者的洗手时间都是固定的。但在真实生活中,如果水温很高或很低,我们就不会洗很长时间的手,而让人感觉舒适的温水则会让我们在洗手池边站更长时间。
Is anti-bacterial hand wash better than soap?
抗菌洗手液比香皂更好?
A lot more research has been conducted regarding this one. Back in 2007 a review of the best studies concluded that the substance mostly commonly found in anti-bacterial hand washes at the time – triclosan – did not reduce the number of bacteria remaining on people’s hands after washing any more than soap did, nor was it any better than soap at preventing symptoms of an infection. A more recent review in 2015 came to the same conclusions.
关于此问题开展了很多研究。早在2007年,就有人总结了这些研究并得出结论说:与普通香皂相比,抗菌洗手液里最常见的杀菌成分三氯生并不会让手上残留的细菌数量更少,同时三氯生防止感染的能力也并不强于香皂。2015年进行的一项研究得出了同样的结论。
Meanwhile a combination of laboratory studies showing that triclosan might increase the risk of anti-bacterial resistance and that it might affect hormone levels in animals, has led to a ban of triclosan in hand washes in the US and in the European Union.
与此同时,多家实验室研究表明,三氯生可能会提高细菌抗药性,同时影响动物体内的激素水平,因此美国和欧盟都发布了在洗手液中禁用三氯生的命令。
So it’s back to soap and water of whatever temperature you prefer.
所以还是用香皂和水洗手吧,同时水温高低也并不重要。
Do you need to dry your hands afterwards?
洗手后有必要擦干/烘干手吗?
When you’re in a hurry it’s tempting to let your hands drip dry. That’s fine if you don’t touch anything on your way out of the bathroom. If you do, you could pick up germs because they transfer to your hands more easily if they’re wet.
你要是有急事,往往等不及让手自然风干。在离开卫生间时,双手最好不去接触任何物体。如果有接触,湿手就会更容易沾染到细菌。
You also miss out on the benefits of drying your hands, which itself can lower the level of any remaining microbes left on your hands.
所以,洗手后尽量让你的手变干燥,这样会减少残留在手上的细菌数量。
Hand dryer or hand towel?
用烘手机吹干还是纸巾擦干?
There’s a lot of debate surrounding this one. Most publications come down in favour of paper towels which get used just once. For a start it can be quicker than waiting for a traditional electric hand dryer to do the job. In a study from New Zealand (which, it must be pointed out, was funded by New Zealand Towel Service) people needed to wait 45 seconds for a dryer to evaporate the excess moisture on their hands. Most of us don’t want to hang around that long.
关于这个问题,人们仍然争论不休。大多数论文倾向于认为一次性纸巾更好。它避免了用老式电动干手机烘干双手所花费的时间。新西兰开展的一项研究(必须指出,这项研究是由新西兰纸巾协会赞助的)表明,人们需要45秒钟才能烘干手上的多余水分。没人愿意站在干手机前花那么长时间。
Now of course there’s a new generation of jet dryers which work faster. They have been shown to dry hands just as quickly and effectively as paper towels. Ten seconds with a towel or a jet dryer leaves hands equally dry.
当然,现在出现了烘干速度更快的喷射式干手机,这种干手机的烘干速度和效果和纸巾相差无几——无论用喷射式干手机还是纸巾,都只需10秒钟就能达到同样的干手效果。
But the jet dryers have come under criticism, with the suggestion that they are so powerful that they could spread germs around the room. A study conducted at Westminster University found the most powerful hand dryers can spread a virus as far as 1.5m across the room and a later study increased this to three metres. But this isn’t cut and dried. Most of these studies have been funded by towel industry, who makes a living selling towels and not electric dryers. Then again, the authors are open about this and the research is published in peer-reviewed journals.
然而,有人批评喷射式干手机说,这种干手机的气流功率太大,会把微生物向整个房间扩散。西敏寺大学(Westminster University)开展的一项研究发现,功率最大的干手机会把病毒散布到1.5米远的位置,另一项研究则把这一数字提高到了3米。然而,这一说法却并非定论。这些研究大多数都是由纸巾企业赞助的,这些企业靠卖纸巾生存,而不是电动干手机。这些文章作者们对于这一问题都保持开放态度,相关论文也都发表在供同行阅读的专业期刊上。
The next step is for more research conducted in real public toilets, rather than in the lab.
下一步,研究的场所应当离开实验室,来到真实的公共厕所。
And again, our preferences need to be taken into account. Any method that encourages people to dry their hands, rather than leaving them wet, is an improvement. Making toilets nicer could make a difference. The study which observed more than 3,000 people in a college town in the US, found that if the toilets were clean and well-kept, people were more likely to stop and wash their hands properly. When the sinks were dirty, they just wanted to get out of there.
与什么都不做,让手湿淋淋相比,任何鼓励人们干手的方法都是一项进步。更加舒适宜人的厕所会带来巨大的变化。美国一座大学城对3,000余位学生进行了调查。调查发现,如果厕所很干净且管理完善,人们就更愿意停下来认真洗手。但是如果洗手池很脏,他们就只想早点出去。
Whichever way you choose to wash and dry your hands, the main finding from research is to do it for longer than you think. To work up a good lather and to the palms and back of your hands as well as cleaning between your fingers, under your nails, and up to your wrists takes at least 15-30 seconds. Try singing Happy Birthday twice (just not out loud if it's a public bathroom).
研究发现,无论你采用哪种方式洗手或者干手,时间都是越长越好。打出大量肥皂沫,充分洗涤你的手掌、手背、指间、指甲缝和手腕至少需要15-30秒时间,这正好是把《祝你生日快乐》唱两遍所需的时间(当然如果要是在公共厕所,请注意控制声量)。