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关于保暖的五个迷思:是真是假?

更新时间:2019/3/30 11:41:11 来源:纽约时报中文网 作者:佚名

Five myths about staying warm in cold weather
关于保暖的五个迷思:是真是假?

1) Don’t turn a fan on

1)不要打开风扇

You might assume that fans are just for summer. After all, why would you want to spread air around the room in the winter? Sounds draughty. In fact many ceiling fans have a reverse setting, specifically aimed at use when temperatures are low. Heat rises of course, which means that the nice warm air above your radiators heads on up towards the ceiling, rather than where you’d most like it – at sitting height if you’re in your living room. This is more of a problem in rooms with very high ceilings. Picture a glossy office building with a tall atrium. Thermal stratification occurs, with warmer air near the ceiling and cooler air lower down where the people sit. So the idea is that if a fan is run on a low setting in reverse, destratification will take place. The nice hot air will be sent from the ceiling back down the walls into the room where it can recirculate and warm you up.

你可能以为只有在夏天才会用风扇,冬天室内还需要风吗?听着就冷。实际上,低温天气里,室内天花板的吊扇应当反方向转动,道理是空气中的热气会上升。冬天,在客厅里,你最希望热气停留在坐着的高度。而在通常状况下,热气会不断上升,意味着暖气片的热气一直上升至天花板,而不是待在你最想让它待的高度。在天花板非常高的房间里,这个问题便更严重。想想一座有着中庭高挑屋顶的华丽办公大楼。发生温度分层时,更温暖的空气集结在天花板附近,而冷空气则停留在人们坐着的地方。所以当风扇开到低档反方向旋转,温度分层便开始消失了。温暖舒适的空气会从天花板附近回到地面,进而产生循环,让你暖和起来。

Research on this has tended to focus on workplaces where businesses are trying to keep vast buildings warm. In warehouses it’s been estimated that the correct use of ceiling fans can reduce energy use by 3% per metre of ceiling height, not inconsiderable in a building that might be 10m (33ft) tall.

关于这方面的研究,主要是在企业办公场所,让大型建筑保持暖和。在仓库中,正确使用风扇能让每1米层高降低3%的能耗。对于一座10米(33尺)高的大厦来说,相当可观。

Instructions for fans tend to suggest running them in reverse in winter (clockwise), in order to draw the air up, but not everyone agrees. There is some interesting unpublished research from Holly Samuelson at Harvard University from 2015.

风扇使用指南建议,在冬天应将其反方向运行(顺时针),将空气拉升,但并不是每个人都同意这种方法。2015年,哈佛大学(Harvard University)的萨缪尔森(Holly Samuelson)有了一些有趣的发现,但未公开发表。

She tested two types of domestic fan on forward and reverse settings in rooms of three different heights. The reverse setting led to warmer air down near the ground, but the forward setting that you would usually use in summer, resulted in warmer air at torso height. So, if you’d like warm feet, then put it on reverse. If you prefer the rest of your body to be warm, put it on the normal setting. She found it was even more successful if the fan was run at a medium rather than a low speed, although then of course you do risk sitting in a draught.

她测试了两种国产风扇在三个不同高度房间内正向和反向运转。反向运转能将暖空气送到地面附近,而人们在夏天常常使用的正向运转则将暖空气送到人体高度附近。所以,如果你想让脚暖和起来,就把风扇反着开。如果你想让身体其他部位暖起来,正常打开风扇就好。她还发现,风扇开着中档速度的效果比低档更好,但当然你身边的风就很大。

If you happen to have a large living room with a ceiling fan in the middle and chairs around the edge, far enough away not to feel the draught, then this research would suggest that forward mode on medium would save the most energy while keeping you warm.

如果刚好你客厅的吊扇在中间,而椅子放在房间边缘、感觉不到风的位置,那萨缪尔森就建议用中档正向运转模式,能最大程度节约能量,同时又保证暖和。

VERDICT: MYTH – depending on how your room is arranged a fan on a low setting might help spread the heat around the room.

结论:“冷天里不要打开风扇”是迷思。这取决你房间中的风扇如何布置,低速运行可能有助于暖空气向房间四周散布。

2) Alcohol warms you up

2)酒精能让你暖和起来

If you’ve been out in the snow, what could be better than a nip of something alcoholic to warm you up? Hipflasks have been carried in the mountains since the 18th Century and mulled wine is still popular in ski resorts today as people come off the slopes and head into a bar to warm up.

如果你在室外的雪地里,一小口酒最能让你暖和起来。从18世纪开始,随身小酒瓶就被带入山里。在滑雪度假村里,热红酒至今仍是人们离开滑雪道、走进酒馆后暖身的首选。

It is true that if you drink an alcoholic drink when you’re cold you will feel as though you’re getting warmer and you’ll look as if you are. The alcohol sends blood towards the surface of the skin, making you flush. If you touch your face it will feel hotter. The problem is the blood has moved away from the main parts of your body, so in fact your core temperature drops.

的确,冷的时候喝些酒精饮料会让你觉得自己正逐渐变暖。看起来也像是这样,酒精令皮肤表层充血,让你脸红,你碰碰自己的脸,也会感到它变热。但问题在于,血液已经离开你身体的主要部位,所以实际上你的核心温度下降了。

The good news is that the discomfort starts to lessen and if you’re now indoors a slight initial drop in core body temperature won’t matter. The problem is that if you’re staying out in the cold the effect of blood moving to the skin is not enough to keep you warm for long. Or if you drink a lot and then go back out into the cold, you could put yourself at risk. Alcohol can reduce the body’s natural shivering response and dampen your perception of cold.

如果你在室内,少量的酒并不会对核心体温影响太大,不适感会逐渐减少。真正的问题是,在户外,酒精促使血液流向表皮,所产生的热感不能长久维持。在大量摄入酒精后进入寒冷环境,可能发生危险:酒精会减少身体自发的寒颤效应,减少对寒冷的感知和防范。

Combine this with the impaired judgement that of course goes with being drunk, and you can see why people sometimes end up in dangerous situations. We’ve all seen the stories of people who fall into icy ditches on their way home from a bar in the freezing cold. Figures from the US show that, in a decade, 10% of deaths due to hypothermia involved alcohol consumption.

加上醉酒后判断力必然减退,你就明白危险的原因了,我们都听过不少人回家时掉进结冰的水沟里的故事。美国的数据显示,近10年来,10%的死亡事件是因为饮酒造成的体温过低。

VERDICT: HALF TRUE – it warms your skin which gives you the sensation of feeling warmer, but your core body temperature can drop. In excess it can increase your chances of hypothermia.

结论:“酒精能让人暖和”只是对了一半。酒精让你体表温度上升,因此你觉得暖和,但你的核心体温可能下降。过量酒精会增加你体温过低的风险。

3) Don’t sit on the radiator or you’ll get piles

3)不要坐在暖气片上,否则你会生痔疮

This is a myth that’s been around for a while. Another is that sitting on cold surfaces gives you piles.  Haemorrhoids or piles are itchy, bumpy swellings that develop from the cushions of tissue lining the anal canal. They affect as many as 50% of people at some point of their lives.

这是一个流传甚广的迷思,另一个是坐在冰冷的东西上也会让你得痔疮。痔疮是肛肠内壁组织产生的凹凸不平、发痒的肿块, 50%的人们都在生命中某个时段受此影响。

Cooling the region can give some people relief, but there’s no evidence that warm temperatures cause them or make them worse. In fact a German study found that people who had a bath at least once a week (which presumably would be hot) had a lower risk of developing piles. (The study can be found here, but be warned that it contains graphic images).

降低这个区域的温度可以让一部分人感到舒服,但是没有证据显示暖和的温度会导致痔疮或者让它们更严重。事实上,一项德国的研究发现,每周至少泡一次澡(热水澡)的人患痔疮的风险更低。

People are at higher risk if they often have constipation and strain when they go to the loo.

如果便秘或者如厕时有压力,患痔疮的风险会更高。

VERDICT: FALSE  – sitting on radiators doesn’t give you piles. The best way to lower your risk is to eat plenty of fibre such as vegetables, cereals and nuts, avoid becoming overweight and drink water.

结论:错误。坐在暖气片上不会得痔疮。降低痔疮风险的最好方法是多吃蔬菜、谷物以及坚果等纤维,避免超重,多喝水。

4) Don’t go out with wet hair or you’ll get a cold

4)不要湿着头发出门,否则你会着凉

My guess is a lot of us were told this by our grandparents. I certainly was. The name “cold” even suggests you catch it by going outside in low temperatures. The illness is of course caused by a virus and unless you catch that virus, you can’t develop a cold. But could getting chilled make you more susceptible?

我猜很多人都听祖父母这么说过,我也是。从字面上理解,在天冷时出门时就会“着凉”。着凉感冒当然是由病毒导致,所以你“得”的是病毒,否则你是不会着凉感冒的。但变冷会让你变得更容易得病吗?

In research where volunteers’ temperatures were lowered before exposing them to a cold virus, some studies found the shivering group were more likely to develop a cold, others that it made no difference.  But Ron Eccles from Cardiff University in the UK tried something different.

有研究发现,当先把志愿者处于低温下,再把他们暴露在感冒病毒下,打颤的小组更可能着凉,其余人则没有分别。但英国卡迪夫大学(Cardiff University)的埃克斯尔(Ron Eccles)则做出了不同尝试。

People had to sit with their feet in cold water for 20 minutes, before returning to their normal lives. The control group kept their shoes and socks on and simply sat with their feet in an empty bucket for 20 minutes. Five days later twice as many people in the cold water group said they now had a cold. It should be said that the study did rely on the volunteers’ own assessments.

实验中,实验组人员在回到正常生活前需要将脚放在冷水里坐20分钟。对照组则是穿着鞋袜,将脚放在空篮子里坐20分钟。五天后,冷水组中表示自己着凉的人比正常组多两倍。需要指出的是,这个研究的确基于志愿者的个人判断。

But why should having wet feet or maybe wet hair make you more likely to catch a cold? One suggestion is that because when you’re feeling cold the blood vessels in the nose and throat constrict, meaning that fewer infection-fighting white blood cells reach your nose and throat to tackle the virus.

但为什么湿着脚或者湿着头发会让你更容易着凉呢?猜测之一是,当你感到寒冷时,鼻腔和喉咙中的血管收缩,意味着更少的抗感染白细胞能抵达该处阻击病毒。

Others suggest that people simply get more colds in winter because they stay inside together and pass their germs around more easily. When Anice Lowen from Emory School of Medicine in the US studied how easily the flu virus passes from one guinea pig to another, she found the warm temperatures with low humidity (typical of a centrally heated house in winter) were ideal circumstances for passing on the infection.

另一猜测则是,人们容易在冬天感冒单纯是因为他们聚在室内、更容易互相传播病菌。当美国埃默里医学院(Emory School of Medicine)的洛文(Anice Lowen)研究流感病毒是如何轻易地在豚鼠之间传播时,她发现低湿度、温暖的环境(特别是冬天中央暖气或空调的房子)是引发感染传播的最佳场所。

VERDICT: MORE DATA NEEDED - going out in the cold with wet hair won’t give you a cold, but it’s possible that if you have already picked up the virus your body might find it harder to fight it.

结论:需要更多数据。湿着头发出门不会让你着凉,但如果你的身体已经感染了病毒,可能抵抗力会变差。

5) Always wear a hat because you lose the most heat from your head

5)要戴帽子,因为大部分热量从头部流失

Obviously it makes sense to cover up well if you’re heading out into the snow, but is it true that it’s especially important to keep your head warm?

如果你去雪地,戴帽子显然符合逻辑。但它是不是对保持头部温暖如此重要呢?

Hardy volunteers have taken part in plenty of unpleasant research on this in the hope of finding some answers. In one study Thea Pretorius from the University of Manitoba in Canada gave volunteers drugs which prevented the body from shivering. Then they were lowered into cold water wearing scuba tanks for breathing. They wore dry suits, socks and gloves or just a swimming costume. Sometimes their heads stayed above the surface of the water. At other times they were completely submerged.

勇猛的志愿者会为了找出答案而参加许多令人不适的研究。加拿大马尼托巴大学(University of Manitoba)的比勒陀利乌斯(Thea Pretorius)在一项研究中让志愿者服用抑制身体颤抖的药物。然后这些志愿者戴上潜水氧气设备,浸入冷水中。他们有人穿着干式潜水服、袜子以及手套或仅穿着泳装。有时他们的头会浮出水面,其余时间他们完全在水下。

If they were submerged but wearing the dry suit, their heat loss was mostly from their heads, but they lost only half as much heat as those in swimming costumes with their heads sticking up above the water. Since they were losing heat almost entirely from their bodies, this shows we lose more heat from our bodies than from our heads.

如果这些志愿者穿着干式潜水服完全浸入水中,那么他们大部分热量应该是从头部流失的。但他们流失的热量仅仅是那些穿着泳衣并保持头部在水上的人的一半。由于后者热量几乎完全通过躯干流失,这表明我们躯干所流失的热量多于头部。

It is also true that if the body is insulated, but the head is exposed to the cold, the body’s core temperature still drops faster than you’d expect, possibly because we don’t shiver if only our head is cold and the reason we shiver is of course to warm us up. Also there are a lot of blood vessels on the scalp close to the surface of the skin, so if blood is cooled as it passes through the scalp, it can then cool the rest of the body as it passes through.

如果将躯干完全保温,结论也同样成立。但将头部暴露在寒冷中时,核心体温下降的速度远超我们的预期。可能是因为如果只有头部寒冷时,我们无法打颤,而打颤能让我们暖和起来。在靠近皮肤的头皮部分又有许多血管,当血液流过头皮后会变凉,然后流过身体其他部位时把那里的温度也降下来。

But this concerns the rate of cooling, rather than the lowest temperature your body reaches. When it’s freezing outside, what usually matters to you is how cold you end up. So the ideal is to keep  the rest of your body and your head well covered.

但这关系到变冷的速度,而不是体温最低降到多少。当环境温度很低时,通常而言,更重要的是你体温最终会降到多低。所以最好还是好好包裹着你的身体和头部。

VERDICT: TRUE that it’s a good idea to wear a hat if you want to keep warm, but FALSE that you lose most heat from your head.

结论:为了保暖而戴帽子是正确的,但要说大部分热量是从头部流失的,则是错误的。

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