As airlines start easing face mask rules, is air travel COVID-safe? We asked the experts

Mar 2, 2022

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The most dangerous person on a plane right now is not the poorly-looking salary man quietly sweating into his handkerchief in business class. Nor is it the air steward walking the aisles dishing out free snacks and drinks. It’s the teetotal professional stage actor loudly telling jokes with perfect diction in English or Chinese.

Or at least, according to experts, it’s the funny ones you should watch out for the next time you travel anywhere by plane.

On 11 February, all travel restrictions for fully vaccinated travellers to the U.K. were lifted, allowing anyone with a COVID-19 pass to enter Britain without having to provide a negative test. Shortly thereafter Boris Johnson also moved to drop all other existing restrictions in Britain on 24 February. As a result, the travel industry began to once again open up like a rare flower that smells of suncream and Sangria.

Related: Ryanair to ditch face masks on flights by spring 

Shortly after the U.K. changes, so followed new EU guidance on pre-departure testing with European countries, from Portugal to Greece, beginning to scrap many testing measures to breathe life back into tourism as British sun-seekers scramble to book holidays after two-years of being cooped up in Blighty.

Then just this week, Jet2 announced that they would become the first airline to scrap facemasks aboard their flights. Hours later, Ryanair released its own statement saying it would like to phase out face coverings by the spring.

The changes come as we learn to ‘live with COVID-19’, while also being keenly aware that new variants, such as omicron, have and could still lead to deadly new outbreaks.

All this has again raised the gnawing question: just how risky is air travel right now?

The air that we breath

To understand the current COVID-19 risks, you need to start with how air circulates on a plane.

“Cabin air quality is not a new topic,” Dr Paolo Alves, Global Medical Director of MedAire, the world’s leading provider of medical and safety advice to the airline industry, tells TPG. “We’ve been working out ways of removing potentially harmful particles from planes since there were fears of anthrax attacks after 9/11.”

All the experts TPG spoke to for this article wanted to dispel the widespread misconception that plane air is just a fog of recycled sneezes and sniffles pumped through the cabin like germ-infused poison gas. “It’s actually quite the opposite,” says Dr Alves.

In fact, according to Dan Freeman, lead engineer for Boeing’s Confident Travel Initiative, a passenger jet’s cabin is “designed to be more efficient than an outdoor breeze.”

“The cabin changes over its air every two to three minutes, which is several times faster than most other places on the planet,” says Freeman. “Operating rooms in hospitals tend to change about every six to 10 minutes, while commercial buildings are much longer than that.”

Related: Jet2 becomes first airline to scrap face masks on flights

Plane air is a mixture of 50% fresh air pumped in from outside and 50% recycled air that’s been dragged through a hospital-grade “high-efficiency particulate absorbing” filter, also known as a HEPA filter – the most advanced air ventilation system known to crowded indoor spaces.

“A HEPA filter is 99.97 effective at taking out virus-sized particles,” says Freeman. “On top of that, air doesn’t flow from one end of the plane to the other. It is blown in from ducts on the ceiling and very quickly jettisoned out through vents in the floors.”

So because the air flows from top-to-bottom rather than longitudinally through the fuselage, the chances of being infected by someone further down the plane are next to zero, he says. “We’ve performed studies that show two people sitting next to each other on a plane breathe in the same number of particles as if they were more than seven feet apart in, say, an office or a bar,” Freeman adds.

Now add that to the numerous methods of disinfecting planes that Boeing has developed – from ultraviolet light wands to electro-static sprays – an aircraft’s cabin is, in short, far safer than any pub, supermarket or other crowded indoor space you go to in your daily life.

But of course, nothing is completely foolproof. And if we’ve learned anything by now, it’s that variants like omicron are slippery assailants, capable of smuggling themselves into our bodies in the most devious of ways.

Slowing the spread

In March 2020, a Vietnamese businesswoman with a sore throat and a cough boarded a flight in London. Ten hours later, she landed in Hanoi, Vietnam; she infected 15 people on the flight, including more than half of the passengers sitting with her in business class.

Then, in September last year,  a man flying from Dubai to New Zealand tested negative for the virus, but was, in fact, infected. He passed it on to other passengers, who were all sitting near him.

It turns out now, however, that these are vanishingly rare examples of in-flight transmission. Indeed, in October 2020, research from The International Air Transport Association (IATA) found just 44 cases where coronavirus is thought to have been transmitted during a flight since the start of the year, out of a total of 1.2 billion passengers who travelled by air. That, the IATA said, gives a one in 27 million probability of catching Covid-19 on a flight.

In other words, you’ve got more chance of being struck by lightning.

Still, while HEPA filters clearly work, they can’t capture all COVID-19 aerosols before you might breathe them in, says British clinical virologist Dr Julian Tang of the University of Leicester.

“We know that an infected person breathes out about 1,000-10,000 viruses every 30 minutes of conversation,” he tells TPG. “And while the massive ventilation system on planes is highly efficient, it doesn’t take many viruses to get infected. I would still wear a mask throughout any flight. I’d only take it off for eating.”

A 2018 study by researchers from Emory University in Atlanta attempted to model how passengers and crew moved about an aircraft, and how that might affect the transmission of infectious diseases. “A droplet-mediated respiratory infectious disease is unlikely to be directly transmitted beyond one metre from the infectious passenger,” they concluded. “Thus, transmission is limited to one row in front of or in back of an infectious passenger.”

While Tang agrees that a plane is safer than any other terrestrial environment, the biggest risk will always be other people. “It depends what kind of traveller you are, and the kind of person you’re sitting next to,” he says. “If you’ve got a very talkative gregarious traveller sitting beside you, bad luck.”

Can you smell my garlic breath?

According to Dr Tang, “if you can smell what I’ve had for lunch when I talk, then you’re also inhaling my virus as well”. He calls this the “garlic breath distance”.

And whatever you do, don’t make anyone laugh on a plane. Flying, more than ever, is a serious business.

Nobody understands this better than Dr Tang, who himself has modelled virus transmission through airflow imaging models (known as Schlieren shadowgraphs) to understand how people spit out virus particles when they talk, cough or laugh. “Laughing produces a massive plume of exhaled air which is probably more dangerous than talking, and just as bad as singing,” he laughs (mercifully, we’re speaking on Zoom).

Studies have even shown that different languages are more transmissible than others. “We looked at English, Mandarin and Malay, and there are certain consonants that produce much more powerful plumes than others. The more prevalent in a language they are, in theory, the more infectious that language could be.”

These are called “aspirated consonants” – the P’s, T’s, K’s and other sounds we make that spray more droplets of saliva into the air. Which is to say: the spittier the language, the more dangerous it could be. And English is one of the worst.

“When we looked at certain languages, we found there are certain consonants that produce much more powerful plumes than others,” says Tang, “Mandarin and English are actually both quite dangerous as there are lots of expulsions of air.”

Japanese, on the other hand, is a much softer language than English or Chinese. “You’re probably less likely to catch COVID-19 in a room full of Japanese people than you are in a room full of Brits,” he says.

But that doesn’t necessarily mean taking a flight to Japan is safer than taking one to China or America. Actually, a short-haul trip to Magaluf with a rowdy stag do singing Swing Low Sweet Chariot three rows down is far worse. “The language itself will of course be secondary to how you speak it,” says Tang. “Someone speaking a risky language in a soft way will be much safer than someone speaking a safer one in a loud way. Laughing is more of a risk than the language you are speaking.”

There’s one other thing: booze. While, as a medical professional, Tang would never recommend drinking alcohol as a way to mitigate your catching COVID-19, he says it does kill the virus in your throat, if only for a very short time. “We know that alcohol does actually temporarily remove the virus from your throat,” he says. “One study has shown that alcohol-based mouthwashes reduce 90% of the virus from your throat. Of course, the virus will also come back after a few minutes.”

And that doesn’t mean you should drink alcohol throughout the whole plane journey, he warns. “It’s also important to remember that the virus also replicates in your nasopharynx in your nose, and you don’t drink through your nose,” he says. “So it probably won’t help that much really. But intrinsically, if you look at the purely in vitro situation of an oropharyngeal model, you have virus secreting from that and you throw alcohol at it, of course, it will suppress the virus.”

One further slap in the face for COVID-19 is that most people flying nowadays will be vaccinated. And Tang says even if a vaccinated person gets infected, many of the viruses they breathe out are “bound to an opsonised antibody complex”, rendering them effectively harmless. “So now the risk on a plane is even lower than we thought because the vast majority of people who travel are vaccinated,” Tang adds.

The transit gauntlet

In truth, all the experts we spoke to agree that the plane is the least of your worries when travelling abroad. To walk through transit is to run the real COVID-19 gauntlet.

“Airports are safer than some other venues because they have very high ceilings so there’s a massive volume in there to dilute any airborne virus,” says Tang. “However, there’s a lot of waiting around, and the ventilation rate in those spaces is not more than four to eight air changes per hour, if that.”

A human body, he says, produces a “thermal chimney” that pushes any viruses you breathe out straight up into the air. There, they’ll float for a while – “from minutes to hours, depending on the ambient air flows in the area” – before settling somewhere else. “Imagine several thousand people in an airport doing that,” says Tang. “That settling effect may still contain some viable virus. That could be a risk if you’re in, say, a customs queue.”

The best advice, then, contradictory to airlines like Jet2 or Ryanair’s recent announcements, is to mask up from the moment you leave your home, to the moment you get to your hotel. “Nothing is 100 per cent, in medicine or in life, but I would not go into a place where people weren’t wearing masks if I don’t know them. Not because masks offer 100 per cent protection, but because I want to minimise my odds of getting it.”

As for Dr Tang, there’s no place a virologist would rather be in a virus outbreak than on a plane. “On a plane, the question is: how long does the virus linger in the air when it’s been breathed out by someone else?” he asks. “The truth is: the massive ventilation system will just whip it away. And this is unique to aeroplanes. They are the safest environment you could possibly be.”

Then he adds: “And if you want to be extra safe, be politely anti-social and watch movies for the whole flight.”

Bottom line

While vaccines have suppressed the spread of COVID-19, variants still pose risks that we’re still only now discovering. However, the world is indeed beginning to open up and shift to a way of living that is no longer stymied by the virus, albeit, a very different world to pre-pandemic days. This shift can only be a good thing for travel and living life.

Yet, remaining cautious is no bad thing. Flying on an aeroplane, though it may feel counterintuitive, remains one of the safer environments you can be in due to the technology and air filtration systems they have in place. But, while the risks of transmission may be lower on flights, facemasks still offer a good deal of protection and are worth persevering with to protect both yourself and those around you. Even if airlines do begin to give up on them as mandatory requirements.

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Photo by Hispanolistic / Getty Images

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