It's a common complaint: Fly on a crowded plane and come home with a cold. What's in the air up there?

经常有这样的抱怨：搭乘了一班拥挤的飞机，回到家就感冒了。机舱的空气中究竟充满了什么？

Air travelers suffer higher rates of disease infection, research has shown. One study pegged the increased risk for catching a cold as high as 20%. And the holidays are a particularly infectious time of year, with planes packed full of families with all their presents and all those germs.

研究表明，航空旅客感染疾病的比率比一般人要高。某项研究更是显示，航空旅客染上感冒的风险较一般人高出了20%之多。尤其是各种假期，往往成为一年当中最容易被传染疾病的时间段，飞机上到处是举家出游的人们，而与他们同行的，还有各种各样的病菌。

Air that is recirculated throughout the cabin is most often blamed. But studies have shown that high-efficiency particulate air (HEPA) filters on most jets today can capture 99.97% of bacterial and virus-carrying particles. That said, when air circulation is shut down, which sometimes happens during long waits on the ground or for short periods when passengers are boarding or exiting, infections can spread like wildfire.

最常遭到诟病的是空气在机舱内的循环流动。但研究表明，如今大部分飞机上的高效微粒空气过滤器能够滤掉99.97%的细菌和病毒微粒。然而，当空气不流通时，例如飞机在地面等候时间过长时或者乘客上下机的时间，细菌和病毒就可能像瘟疫一样快速散播。

One well-known study in 1979 found that when a plane sat three hours with its engines off and no air circulating, 72% of the 54 people on board got sick within two days. The flu strain they had was traced to one passenger. For that reason, the Federal Aviation Administration issued an advisory in 2003 to airlines saying that passengers should be removed from planes within 30 minutes if there's no air circulation, but compliance isn't mandatory.

Jason Schneider安检区域可能会让人感觉不适。等待安检的队伍中充满了咳嗽和打喷嚏的声音；乘客的鞋子脱掉后与其它随身物品一起被放在塑料箱里，而这些塑料箱经过扫描仪后一般并不会得到清洁。1979年进行的一项广为传播的研究发现，在熄火且无空气流通的飞机上连续坐三个小时后，54名乘客中有72%的人在两天内病倒了。在其中一名乘客身上，研究人员发现了导致其他乘客病倒的流感病毒株。鉴于此，2003年，美国联邦航空管理局(Federal Aviation Administration)向航空公司发出一个通告，提出在机舱空气不流通的情况下，乘客应当在30分钟内得到转移。但该通告并不具有强制性。

Much of the danger comes from the mouths, noses and hands of passengers sitting nearby. The hot zone for exposure is generally two seats beside, in front of and behind you, according to a study in July in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention.

很大一部分传染风险来自邻座乘客的口、鼻和手。美国疾病控制与预防中心(U.S. Centers for Disease Control and Prevention)主办的杂志《新发传染病》(Emerging Infectious Diseases)刊登的一项在7月份进行的研究显示，在飞机上最容易传染疾病的高危险区域一般是你旁边、前面及后面的两个座位。

A number of factors increase the odds of bringing home a souvenir cough and runny nose. For one, the environment at 30,000 feet enables easier spread of disease. Air in airplanes is extremely dry, and viruses tend to thrive in low-humidity conditions. When mucous membranes dry out, they are far less effective at blocking infection. High altitudes can tire the body, and fatigue plays a role in making people more susceptible to catching colds, too.

一些客观事实也增大了航空旅客下飞机后染上咳嗽和流鼻涕症状的风险。例如，距离地面三万英尺的高度令病菌更容易传播。机舱内空气极其干燥，病毒在低湿环境下更容易存活。而当粘膜过干时，阻隔病菌的能力就会大大减弱。高海拔也容易令人体感到疲倦，因此使人更容易受到感冒的侵袭。

Also, viruses and bacteria can live for hours on some surfaces岸some viral particles have been found to be active up to a day in certain places. Tray tables can be contaminated, and seat-back pockets, which get stuffed with used tissues, soiled napkins and trash, can be particularly skuzzy. It's also difficult to know what germs are lurking in an airline's pillows and blankets.

此外，病毒和细菌在某些物体的表面能够存活长达数小时──据发现，一些病毒微粒在某些地方的存活时间甚至长达一整天。折叠餐桌就可能被污染，座椅靠背上的袋子装满了用过的纸巾、脏餐布和各种垃圾，更容易藏污纳垢。还有飞机上提供的枕头和毯子，也很难知道有哪些病菌藏在上面。

Research has shown how easily disease can spread. Tracing influenza transmission on long-haul flights in 2009 with passengers infected with the H1N1 flu strain, Australian researchers found that 2% passengers had the disease during the flight and 5% came down within a week after landing. Coach-cabin passengers were at a 3.6% increased risk of contracting H1N1 if they sat within two rows of someone who had symptoms in-flight. That increased risk for post-flight disease doubled to 7.7% for passengers seated in a two-seat hot zone.

研究告诉我们，疾病很容易传播。2009年，一些澳大利亚研究人员追踪了感染H1N1流感病毒的乘客在长途飞机上的流感传播过程，他们发现，在乘坐同一航班的乘客中原本只有2%是病患，但结束飞行后的一周内有5%的乘客生了病。对于普通舱的乘客而言，如果距离其两排以内的某位乘客在飞行途中已有H1N1流感症状，那么该乘客感染H1N1流感病毒的风险将增加3.6%。而如果是前后两个座位之间的高危险区域，那么这种下机后染病的风险还会增加一倍多，达到7.7%。

The epidemic of severe acute respiratory syndrome (SARS) in 2002-03 suggested a wider exposure zone, however. On one flight studied, one passenger spread a particular strain to someone seated seven rows away, while people seated next to the ill passenger didn't contract the disease.

不过，2002-2003年流行的严重急性呼吸系统综合症(SARS)似乎具有更广的传播能力。在一个接受研究的航班上，一名乘客将其携带的某种病毒株传染到了与其相隔七排座位之远的另一名乘客身上，而紧邻该患病乘客而坐的几位乘客却没被染上这种病毒。

That said, most people sitting near someone who is ill probably won't get sick. 'When you get aboard an aircraft, most of us don't have a say on who we sit next to. But that doesn't doom you to catching the flu,' said Mark Gendreau of Boston's Lahey Clinic Medical Center.

波士顿莱黑临床医学中心(Lahey Clinic Medical Center)的马克•让德罗(Mark Gendreau)表示，大部分座位靠近患病乘客的人可能并不会生病。他称，大部分人在乘坐飞机时，都不会跟邻座的陌生人交谈。（与患病乘客）坐得近并不意味着你就会染上流感。

In 2005, he was part of a team that published a paper in the Lancet that concluded the perceived risk for travelers was higher than the actual risk, and that's still the case today, he said.

2005年，让德罗参加的一个研究小组在《柳叶刀》杂志(The Lancet)上发表了一篇论文，指出乘客被传染疾病的实际风险并没有人们所以为的那么高。让德罗表示，现在情况依然如此。

Even so, there are some basic precautions passengers can take to keep coughs away.

尽管如此，航空旅客还是应该采取一些基本的预防措施，让感冒远离自己。

Hydrate. Drinking water and keeping nasal passages moist with a saline spray can reduce your risk of infection.

补水。多喝水，使用盐水喷雾剂，让鼻腔保持湿润，可减少被传染的风险。

Clean your hands frequently with an alcohol-based hand sanitizer. We often infect ourselves, touching mouth, nose or eyes with our own hands that have picked up something.

勤洗手。用含酒精的洗手液勤加洗手，我们常常是用拿过东西的手接触自己的嘴巴、鼻子或眼睛后，传染了病毒。

Use a disinfecting wipe to clean off tray tables before using.

在使用折叠餐桌前，先用消毒湿巾彻底清洁一遍。

Avoid seat-back pockets.

尽量不要使用座椅后背的口袋。

Open your air vent, and aim it so it passes just in front of your face. Filtered airplane air can help direct airborne contagions away from you.

打开座位上方的通风孔，调整风向，让风从你面前吹过。过滤后的机舱空气有助于将潜在传染源吹到别处。

Change seats if you end up near a cougher, sneezer or someone who looks feverish. That may not be possible on very full flights, but worth a try. One sneeze can produce up to 30,000 droplets that can be propelled as far as six feet.

如果你的座位附近有人咳嗽、打喷嚏或看起来像是在发烧，最好换个座位。当然，要是机舱已经坐满了人，换位置可能不太容易，但还是值得一试。一个喷嚏可能打到六英尺开外，里面含有约三万个细菌。

Raise concerns with the crew if air circulation is shut off for an extended period.

如果机舱内空气长时间不流通，可以向机组人员提出你的顾虑。

Avoid airline pillows and blankets (if you find them).

避免接触机上的枕头和毯子（如果有的话）。

"If you take the proper precautions, you should do quite well,' said Dr. Gendreau. 'In most of us, our immune system does what it was designed to do protect us from infectious insults."

让德罗表示，只要采取适当的预防措施，就能够起到很好的效果。对于我们大多数人来说，自身的免疫系统能够发挥应有的作用──将传染性病毒拒之门外。

Hidden Dangers in Security

安检处的传染隐患

You think the plane is bad? Security checkpoints harbor a host of hazards as well, researchers say.

你觉得飞机上很糟糕？研究人员发现，其实安检处也好不到哪里去。

People get bunched up in lines, where there is plenty of coughing and sneezing. Shoes are removed and placed with other belongings into plastic security bins, which typically don't get cleaned after they go through the scanner.

人们一个挨着一个地排队等候安检，队伍中充满了咳嗽和打喷嚏的声音。鞋子脱掉后与其它随身物品一起被放在塑料箱里，这些塑料箱经过扫描仪后一般并不会得到清洁。

A National Academy of Sciences panel is six months into a two-year study that is taking samples at airport areas to try to pinpoint opportunities for infection.

美国国家科学院(National Academy of Sciences)的专家小组展开了一项为期两年的研究，旨在通过对机场各处区域进行采样分析，以精确定位传染风险。目前此项研究已经开展了六个月。

With limited resources, airports and airlines have asked researchers to help figure out where best to target prevention, said Dr. Mark Gendreau of Boston's Lahey Clinic Medical Center who is on the panel.

让德罗是这个专家小组的一名成员。他表示，由于资源有限，机场和航空公司已经向研究人员寻求帮助，以找出哪些区域最应当采取防范措施。

Check-in kiosks and baggage areas are other prime suspects in addition to security lines, he said.

他补充道，除了安检通道，登机亭和行李处也是最受怀疑的高危区域。