The risk of getting sick on a plane is lower than you might think — if you know what to watch out for

• Nonessential travel is still not recommended in many places, such as in the US, where the Centers for Disease Control warns against it.
• Though traveling isn't recommended, the CDC says that "most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on airplanes."
• Some experts agree, and say that there are certain things you can do to minimize risk of infection on flights.
• Frequent handwashing, wiping down the tray table, wearing a mask, and having the vent above you blow air down can help reduce risk.
• But the biggest issue is difficulty in maintaining distance from other passengers; outside of the plane, standing in lines at the airport and eating at a shared table in a terminal restaurant also pose a risk.

You've probably heard someone complain about how they always catch a cold after flying. Maybe you are that person.

Or perhaps you've seen those GIFs showing how germs from someone sneezing can spread all over the plane, or reports that shed light on the dirtiest parts of a plane (yes, tray tables are germier than airplane bathrooms).

While nonessential travel is still not recommended in many places — such as in the US, where the Centers for Disease Control warns against it — you might be wondering how safe it really is to fly right now. Are airplanes vessels of disease, best avoided during a global pandemic, or are they no riskier than, say, a trip to the grocery store?

We spoke to four experts to find out what the risks look like.

It's worth noting that if you do choose to travel, it's best to check each state's health and travel advisories, and the CDC's travel recommendations by country.

In terms of air circulation, experts say planes are essentially as safe as hospitals

The Centers for Disease Control (CDC) states on its website that "most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on airplanes."

Some experts agree.

Joseph Allen, an assistant professor of exposure assessment science at Harvard University and co-author of the book "Healthy Buildings," told Insider that the air on planes is "clean and highly filtered."

Having studied airplane cabin air quality for over a decade, Allen says: "We have to approach this not just from a medical side, but also understanding the engineering side. When you take a step back and look at how the airplane functions, you quickly see that the airplane is getting a lot of fresh air."

He explains that air on planes comes through the engine from outside, and is usually a 50/50 mix of fresh and recirculated air. The recirculated air goes through a HEPA filter, which is used in hospitals and removes 99.97% of all airborne particles, such as germs and viruses. He adds that airplanes get 10 to 12 full air changes per hour, which is on par with what the CDC recommends for airborne infection isolation rooms in hospitals.

"When an infectious passenger coughs or sneezes, the large droplets are going to fall to the ground. So they're not going to be floating around the cabin. It's the small aerosols that are going to float around the cabin, and hopefully [those] are wiped up by the HEPA filter," said Howard Weiss, a biomathematician and professor in the School of Mathematics at Georgia Tech and an adjunct professor of biology and public health at Emory University. Weiss also co-authored a study titled, "Behaviors, movements, and transmission of droplet-mediated respiratory diseases during transcontinental airline flights."

He adds that it's believed that the flu and the coronavirus, for example, are mostly transmitted by the large droplets, though he says there are some indications of "super spreading events that may be caused by aerosols" for COVID-19.

Claiming that air on planes is probably fresher than the air in your house or office, Weiss says "what that means is that an infectious aerosol won't linger for long periods of time on a plane."

The International Air Transport Association is on the same page, stating on its website that "the risk of catching an infection on an aircraft is typically lower than in a shopping center or office environment."

With current heightened cleaning protocols, the likelihood of getting infected from airplane cabin surfaces is relatively low, though you should be careful when touching anything

"The issue is really who's next to you, and then the surfaces you touch a lot," Charles Gerba, a professor of virology at the University of Arizona who has also studied germs on planes, said.

However, he adds that the current cleaning protocols implemented by most airlines, which disinfect planes between flights in many cases, "should take care of a lot of the concerns with that." In fact, going forward airlines will increasingly focus on hygiene, with ideas such as plastic dividers between seats or in-flight janitors already circulating.

Gerba says that tray tables are the dirtiest place on a plane, according to his studies, and that he's detected influenza virus, norovirus, and parainfluenza virus, which causes the common cold, on them.

"The reason that the trays get so contaminated is because that's where your hands are. You're contaminating it all the time by picking it up. So what we generally recommend is you bring a hand sanitizer with you, try to avoid touching your face, or wear a mask, and I think the risks are minimized." He says to avoid the tray table entirely if you can, and to be careful using the bathroom latch and taps, and the overhead vents.

Weiss agrees, saying that indirect transmission of most respiratory infections (touching something that someone who is infected touched) can for the most part be staved off "by using hand sanitizer religiously if you touch any surfaces in the airplane cabin."

"I think that the risk has always been primarily through inhalation, but it doesn't mean that the surface route is not important, or we don't need to worry about wiping down surfaces or washing our hands and using hand sanitizer. I still think that's very important from an infection risk reduction," said Paloma Beamer, associate professor of environmental health sciences at University of Arizona and president of the International Society of Exposure Science.

According to newly revised guidance on the CDC's website, the coronavirus "does not spread easily" from contaminated surfaces.

The main issue putting travelers at risk for infection on planes is difficulty in maintaining enough distance from others

According to Allen, there are "very few examples of outbreaks happening on an airplane," at least relative to the millions of flights annually. However, he adds that "proximity to the infectious patient or person is the key risk factor."

Gerba agrees, but says "it's only really the immediate area around you" that puts travelers at risk. He says that because the air on planes goes around, instead of back and forth, "studies have shown in outbreaks on planes it's usually the people on either side of you or front and back of you." And while Gerba says, "you can get diseases on planes," he adds that it comes mainly from "the people just right immediately next to you."

Allen says it's down to "the luck of the draw," and whether you sit next to someone who is not only infectious but also asymptomatic, as he hopes that symptomatic patients are screened out of flights at this stage.

"It'd be the same risk if you went out grocery shopping — what are the odds you happen to be next to somebody in line with an infection?" he said.

Beamer says that the main issue on a plane is the inability to control your environment.

"If you're on a full plane and you sit down next to somebody who is sick, there's not really a whole lot you can do. You don't have as much control over your exposure on a plane versus other environments. Like, when I'm at Trader Joe's, I can still move away," she said.

According to Beamer, travelers can have up to 20 other passengers within six feet of them on a full flight, but adds that six feet is really just a suggestion. "Six feet 1 inch doesn't make you safe, neither does 5 feet 10 inches make you not safe — it's kind of a range. Some people are going to release a lot more virus when they're sick than other people," she said.

Essentially, your probability of getting infected changes depending on how close or far you are from an infected person. Your dose of exposure is another factor, which can depend on how long you spend exposed.

"What our study showed was that if direct transmission, large droplet mediated infectious disease variance falls within a meter or two (3-6 feet), then unless you're seated close to the infectious passenger [...] you have quite a low probability of getting infected," Weiss said.

Close, to Weiss, means the CDC standard for most infectious diseases of three feet.

While many flights are currently operating at low capacity, and some airlines are keeping their middle rows empty, this likely won't last. According to a press release by the International Air Transport Association (IATA), social-distancing measures can reduce planes' maximum load factors to 62%, when most airlines need their planes to be 77% full to break even. Thus, the IATA anticipates fares rising by up to 54% in some places, though this could also mean that flights will simply get filled right back up as soon as there's demand again.

Gerba suggests wearing a mask, not only because it reduces the spread of airborne droplets, "but it keeps you from touching your nose and mouth, which are potential routes of transmission of virus."

While Weiss acknowledges that your level of protection really depends on the kind of mask you wear, he says that "wearing a mask and washing your hands religiously, I think those are the best things you could do."

Allen also suggests keeping the vent above you on and blowing air down.

The plane cabin shouldn't be your only concern: dirty surfaces in terminals, time spent in lengthy security lines, and waiting to board in unventilated jetways are also risk-factors, among others

The CDC says that yes, air travel can increase your risk of contracting COVID-19, but clarifies that this doesn't necessarily mean that the risk is only on the plane itself.

"Air travel requires spending time in security lines and airport terminals, which can bring you in close contact with other people and frequently touched surfaces," the CDC writes.

Allen thinks that there are many situations outside of the airplane cabin that deserve our heightened attention.

"If you look at the whole travel experience, you can't disentangle the time in the airplane from these other environments, which may be higher risk," he said, pointing to taking public transportation to the airport, standing in tightly packed lines for check-in, security, and boarding, and potentially eating at a contaminated table in the terminal. He adds that travel often disrupts your sleep cycle and diet, which can also impact your immune system.

His research has also found that often the gates and jetways at airports don't have ventilation running while people board and disembark, which he says needs to change in order to prevent the spread of airborne viral particles infectious people might be shedding.

"We have to place the risk on an airplane in the context of other risks, we can't just point to one environment. If everyone's focus is on the tray table, rather than their entire time through the airport, then that's a mistake because that means they're not paying as much attention to other areas that are higher risk. Those are things that are controllable risks," Allen said.

"I'm not saying we shouldn't take additional precautions during a pandemic, it's just to highlight that the time on the airplane is lower risk compared to these other environments," he added.

The window seat can somewhat reduce your risk of infection

"Because people are walking by you in the aisle seat, it's shown in outbreaks and norovirus that people are more likely to get ill if they sit on the aisle because people are touching surfaces and walking by. So based on norovirus outbreaks, the window seat is better," said Gerba.

Weiss agrees. "What we found was under normal circumstances — again, we're talking direct transmission of large droplet transmitted infectious diseases — if you sit in a window seat, you are more than a meter (3 feet) away from the aisle," he said. "So if you believe in the one-meter cut-off for infectious droplets, then you're going to have far fewer close proximity contacts. So yes, there's some added benefit to sitting in a window seat. It's modest, but it's certainly a benefit."

It's on travelers themselves to help reduce risks

"The airlines have a lot of responsibility here, but let's not ignore the responsibility of the air traveler," Allen said, citing that travelers should stay home if they're sick, wear their mask throughout the entire trip, and maintain physical distance.

Currently, air travel is slightly up again — the Transportation Security Administration (TSA) reported 441,255 people flying on June 7 — but that's only in comparison to its record low of 87,534 people in April. To put the numbers into perspective, on the same weekday in 2019, the TSA saw 2,669,860 people passing through their checkpoints.

Allen says that travelers should continue to ask themselves whether the trip is really necessary.

"This is not a green light that everyone should run out to the airport tomorrow morning and fly," he said. "While the science shows that the risk is low on an airplane, airplanes are also good vectors of disease. They move people around the country and the world efficiently, and can bring someone who is sick to an area that maybe doesn't have an outbreak happening."

"You have to ask yourself, is it necessary? Do you have any personal risk factors that put you at higher risk? Are you willing to do your part? Are you willing to keep your mask on? Are you willing to wash your hands frequently? Are you willing to maintain physical distancing?" Allen asks.

"I think if we do all of that, and the airport does their role, the airlines do their role, and air travelers do their part, we can get back to a place where we can start to increase the amount of air travel we have."

• Read more:
• 15 European destinations that are among the least affected by the coronavirus
• Summer travel won't be canceled this year, experts say — but they predict it will look very different
• Cheaper flights and flexible cancellation fees might be here for a while. Here's what air travel may look after the pandemic.
• I'm a flight attendant who is back at work after testing positive for COVID-19. Here's what my experience has been like.