How safe is it to fly right now? We asked an expert

Because the virus is still relatively new, there’s little data on how it can spread between air passengers. But a 2018 study from Atlanta’s Emory University tried to model the transmission of other respiratory illnesses between crew and passengers moving around an aircraft – and suggested they are unlikely to be transmitted via air to anyone further than one metre from an infectious person. ‘Thus,’ it concluded, ‘transmission is limited to one row in front of or in back of infectious passengers.’

Thanks to top-of-the-range ventilation systems, it should be noted that the air on planes is inherently very clean. (A panel of UK experts recently compared it to the air in an operating theatre.) Air is taken from outside the aircraft and mixed with recycled air from the cabin, which has been passed through an HEPA (high-efficiency particulate air) filter similar to those used in hospitals. The current virus is about 125 nanometres in diameter – well within the particle size range (10 nanometres and above) that the filters can capture.

The flow of air is also designed to reduce the risk of infection on board: it flows vertically from above passengers’ heads before being released into the atmosphere via exhausts beneath your feet.

Aircraft manufacturers have now started publishing their own research into the transmission of the virus. A recent joint publication by Airbus, Boeing and Embraer, for example, found in a series of simulations that airflow systems on their aircraft were largely effective in controlling the movement of particles and limiting the spread of viruses. Separately, Boeing found that the combination of their cabin design and airflow system helped created the equivalent of two metres’ physical distance (say, in an office, bar or restaurant) between every passenger – even on a full flight.

That’s the good news. But while the ventilation systems may be effective, researchers say they cannot prevent all infections. The flow of air is constantly disrupted by crew moving down the aisles and passengers leaving their seats. And according to Dr Tang, the majority of infection during a plane journey will stem from close-range, face-to-face conversations (which are unaffected by the plane’s internal airflow).

‘The ventilation system tries to stop transmission front to rear,’ he says. ‘But it’s not so effective at preventing transmission laterally. If you’re talking to someone right next to you, that may not be very safe, because their air will reach you before it gets filtered by the circulation system in the plane.

‘The problem is that people sit so close together, and the effects of the ventilation system don’t normally kick in until the exhaled air from each passenger has been circulated somewhat.’ And, of course, there’s no way to be sure that your fellow passengers aren’t infected.

Even if you aren’t sitting next to (or very near) someone with the virus, you may still be at risk. An earlier study from the same Emory team showed that passengers with Sars (a closely related infection that hit headlines in 2003) or flu appeared to infect some people well beyond their immediate area.

The scientists theorised that some of those who became ill were infected not by breathing in infected droplets, but by other means: waiting in the airport, embarking or disembarking, or touching contaminated surfaces. Viruses could survive for hours on shared armrests, toilet-door handles or seat trays. If you were to touch these, then your mouth or nose, you would be putting yourself at risk of infection.

The paper also pointed out that unwell crew, who regularly have to move up and down aisles, could be a significant source of infections. ‘It is imperative that flight attendants not fly when they are ill,’ the authors said.

Nonetheless, the latest 2020 data suggests that in-flight transmission is still rare, in any form. From the start of the year to October, there were only 44 reported cases of infection linked with a flight journey (including confirmed, probable and potential cases), according to the International Air Transport Association. Some 1.2 billion passengers have flown on more than 16 million flights over the same period, the trade body added. While it is likely those case figures are a significant underestimate, it is clear that flights are by no means transmission hotspots.

The risk of airborne transmission may be less in airports, as you’ll likely be able to keep a greater distance from strangers. But the ventilation systems in airports are ineffective in preventing the spread of the virus, according to Dr Tang. ‘The ceilings are so high, and the tiny exhausts for the ventilation so far away from people, that, to be honest, they’re probably not helping.’

And when it comes to contaminated surfaces, from check-in to boarding to baggage claim, the risks are as high here as they are in plane cabins. ‘Eating places and public restaurants especially, without them being wiped down first, could lead to some low-level contact transmission,’ says Dr Tang.

Since airlines started resuming flight schedules, many have introduced new policies to maintain at least some degree of social distancing between passengers. In North America, for example, Southwest, Alaska, JetBlue and Delta have all blocking out middle seats to ensure distancing throughout the year. Most airlines in Europe, on the other hand, aren’t limiting capacity at all.

That may change as evidence mounts that this could be an effective way to minimise the risk of infection. A recent study from the Massachusetts Institute of Technology found that by blocking out the middle seat, the risk of catching the virus was cut by almost half. ‘Any distance is better than none,’ says Dr Tang. ‘If you’re sitting right next to someone, that’s much higher risk than you’re sitting on the next-but-one seat.’

Most airlines are now using electrostatic antimicrobial sprays to disinfect flights, either overnight or between flights. Many are offering disinfectant wipes and hand sanitiser to passengers, and some – including Emirates and Malaysia Airlines – have offered flyers complimentary hygiene kits including a face mask, wipes and sanitiser. Most are also giving staff some form of PPE.

Almost all carriers have now made it compulsory to wear a face covering in cabins. Airports are also largely doing their bit to create a safe, clean environment for passengers and staff. Many have increased the frequency of cleaning schedules, introduced new sanitiser stations, installed plexiglass shields in front of passenger-facing employees and allowed passengers to unpack their own items during security checks.

As to whether or not masks are mandatory in airports: that depends on the local laws or guidelines on wearing coverings in indoor public spaces. If masks are required, there will likely be exceptions if you’re eating or drinking, or need to pull the mask down for identification.

The only way to eliminate risk is to not fly at all – so think about whether your trip is strictly necessary. If it’s a short-haul flight, and you can, think about driving instead.

External variables that may increase the risk of catching the virus include the infection levels where your flight is departing from and where you’re heading. You should be particularly careful if you are older or more vulnerable due to a pre-existing condition, or visiting someone in that position.

If you do fly, there are plenty of simple precautions you can take. Avoid checking in bags and plan your timings so you can spend as little time as possible in the airport. If there is an outdoor terrace, then try to stay there.

Even though most airlines and many airports are now providing wipes and sanitiser, you should bring your own so you can make sure to disinfect surfaces, like your seat belt, and personal belongings, like your passport. You could also bring wipe-friendly zip bags in which to carry your ID. Wash your hands or use sanitiser as often as you can – preferably every time you touch any surface.

When it comes to staying safe in the cabin, try to book a window seat. Having a wall on one side will significantly reduce the number of people you are exposed to. If you’re travelling as a group, try and make sure you sit together: splitting up will increase your risk of exposure.

Once you’re seated, you should make sure to turn on the air vent above your head. ‘If you turn on the ventilation stream, that creates an air barrier between you and the other passenger,’ explains Dr Tang. ‘It shoots down and it pushes out anything you breathe out.’ Then stay put and avoid walking up and down the aisle, as this could bring you into contact with contaminated air from other passengers.

Finally, as the World Health Organisation, the vast majority of governments and every airline are now advising or requiring, you should also wear a mask. A recent review, published in the Journal of Travel Medicine in September, brought together all available data on in-flight transmission and concluded that ‘strict use of masks appears to be protective’.

‘If we all wear masks, we all protect each other,’ added Dr Tang. ‘You also protect yourself somewhat, using the mask. If you mask, then you reduce the incoming aerosols [tiny air particles] by about six-fold, and you reduce the outgoing aerosols by about 20 or 30-fold. That protection works both ways, for everybody.’