Every year, millions of people follow a similar Holiday To-Do List in preparation for heading off for the season:
Survive the company party — check
Buy presents for your loved ones — check
Make it to the airport on time and with your ticket — check
Manage them all? Congratulations. Buckle up and settle in for the flight. All is well until the inevitable happens: A distressing, hacking noise breaks out somewhere within the cabin. Someone onboard has a cough, and they are poised to ruin your well-deserved holiday break with an infectious disease.
With hours to go until the final destination, you’re trapped. But your vacation isn’t doomed. The science of in-flight microbe travel explains why.
Vicki Hertzberg is a scientist at Emory University’s school of public health and a member of Boeing’s Fly Healthy research team, who sponsored her 2018 study published in Proceedings of the National Academy of Sciences.
She tells Inverse that as long as you’re in good health ahead of time, take some pre-flight precautions, and exercise restraint there’s a way to make it off that plane health intact.
Fear the passenger, not the plane
Planes can be as unclean as any other mass transit, but when it comes to catching something, what you really have to worry about is proximity to a spewing passenger, Hertzberg says.
"There wasn’t enough spewing into the air that got onto surfaces."
But even if that person is coughing and touching stuff in the cabin, you are probably going to be okay.
Between October 2012 and March 2013, Hertzberg recruited ten graduate students and had them ride ten flights. Eight of the ten flights either originated from Atlanta during a flu outbreak, or traveled to a place where there was a flu outbreak.
The students listened for coughers on the flights (they only found one), swabbed seats, seatbelt buckles, and armrests, and tested the air for 18 common respiratory infections. All of the 229 samples came back negative for pathogens.
“There wasn’t enough spewing into the air that got onto surfaces. And we actually looked for coughers as well,” Hertzberg says.
Respiratory diseases like the flu are spread through “droplets.” These droplets go flying through the air when someone coughs or sneezes. The rule of thumb is that these droplets don’t travel further than about three feet, she says. The Centers for Disease Control and Prevention’s flu guidance disagrees, however, stating that droplets can reach people up as far as six feet away.
It’s concerning aboard a flight — you only have so much space after all — but not if the person is farther away than that.
The one-row rule
Sitting within two rows of a sick passenger puts you at risk of infection, according to a study Hertzberg conducted in 2016. But she thinks that it might actually be just one row.
“The people you really have to worry about are the people beside you between two seats each way — including the people in the row in front and the row behind you. If someone five rows behind you is coughing and hacking, they’re probably not the person you have to worry about,” she says.
Hertzberg describes a hypothetical scenario that illustrates the so-called splash zone. Imagine that the aforementioned cougher is seated in 14C (a mid-cabin aisle seat) in this diagram:
The people most at-risk for getting sick would be seats 13A through 13D, 15A through 15 D, and naturally, those right next to the cougher, including the person across the aisle (outlined in red). These people would have between and 80 and 100 percent chance of infection.
From there, the rate of infection tapers dramatically — even if you are just two rows away.
"If you are concerned about protecting yourself, the masks that are commonly seen do nothing."
If you move behind the cougher (outlined in orange), the probability of infection is about 1-2 percent. In the row directly in front, probability of infection was as little as 1 percent (outlined in purple).
These are extremely generous estimates, Hertzberg says. They are partially based off a disastrous 1977 incident where 72 percent of passengers on a landed plane got sick when they sat on the tarmac for 4.5 hours with an inoperative air ventilation system. Also, the estimates only apply to common respiratory infections. The CDC has more robust policies for passengers seated near people with serious communicable illnesses, like measles or tuberculosis.
But, if the person next to you is coughing, there is a chance you will get sick. Which begs the question: Is it worth bringing along one of those medical masks, just in case?
“If you are concerned about protecting others from your illness, by all means, wear a mask,” she explains. “However, if you are concerned about protecting yourself, the masks that are commonly seen do nothing.”
A more prudent course of action is to think carefully about where you book your seat and exercise some in-flight restraint.
Tricks for staying healthy in-flight
- Get anti-social
To stay healthy, reduce the amount of people you come into contact on the plane, Hertzberg says. On flights between three and five hours long, those who sit in window seats have an average of 12 contacts per flight. Those in middle seats had an average of 58 contacts and those in aisle seats had 64 contacts.
There could be more contacts on longer flights. But the window seat is still the best option, she says.
- Don’t move around
Once you’re in your window seat, you should do your best to stay there, Hertzberg says. The more often you get up on a plane, the more people you come into contact with — and the more likely you are to enter the splash zone.
“Don’t move. Get in your seat and stay there,” she says.
- If you need to go, try the front lavatory first
But for many fliers, nature inevitably calls. Using the restroom, or waiting for it, was the most common activity observed during the 2018 study.
Surprisingly, the wait for the rear lavatory is twice as long as the wait for the front-of-cabin bathroom. In the rear, the average wait time was 3.1 minutes, but in the front it was 1.7 minutes. A more express visit could reduce contact with other potential sick passengers.
Of course, taking care before boarding matters, too, as does following basic hygiene in-flight. Washing your hands and refraining from touching your face are both simple ways to improve your odds of staying healthy, Hertzberg says. In the meantime, settle down, plug in the headphones and slip on the eye mask — think of it as some well-earned ‘me’ time.