Fly Smarter

Yes, planes have great air-filtration systems, but they’re not quite COVID-free zones. Here’s how you can avoid bringing the virus home with you.

Liz Ruark
Passengers on an airplane, wearing masks

Folks, I flew on an AIRPLANE a few weeks ago! It was amazing to be traveling long distances again for the first time in over two years. I wasn’t quite as excited as the preschooler in the row in front of me, who, while the plane was taxiing, kept asking when we were going to “blast off.” But I was close.

If you have air travel in your future, you might be excited like me and my preschool flight buddy. But you might also be nervous about the prospect of a COVID-era trip sealed in an aluminum can with a herd of other people breathing their germs all over the place. No matter which end of the spectrum you lean toward, there’s info you need to know before you fly these days:

Big planes have great air-filtration systems — but first you have to get on the plane.

Yes, it’s true! Big airliners have cool systems that not only filter the air extremely well, but also bring in outside air. Plus, they mix it all together so that stale air doesn’t hang out anywhere. (The New York Times has a fantastic animation that lets you see how the whole thing works.)

While that’s great news, here’s the thing: When you travel, you don’t magically teleport from your house to your airplane seat. You have to get through a bunch of other crowded indoor spaces on the way there, and those places don’t have fancy air cleaners — places like airport shuttles, security lines, and gate areas. Think about how small the jetway is (it’s the little tunnel between the gate and the plane), and how close people are to one another in there. That’s a very high-risk space when it comes to COVID-19. Plus, the air-filtering system in planes doesn’t get started until the plane is flying — the jet engines are what makes it work. How long do you usually have to wait before everyone’s buckled in and the plane is taking off? That’s a lot of unfiltered breathing time for all those folks around you.

Professor Jose-Luis Jimenez of the University of Colorado, an expert in how people catch airborne diseases, did a neat experiment while on an international trip in April 2022. He brought with him a small device that measures the amount of carbon dioxide in the air and checked the levels in different places throughout his travels. (Carbon dioxide is the main gas you breathe out when you exhale.) Well-ventilated room air has fewer than 800 parts per million (ppm) of carbon dioxide. By the time his plane to Madrid was getting ready to take off, the carbon dioxide level in the air was over 2500 ppm - the air was filled with other people’s breath. If anyone on that plane was infected, the virus was in the air, too.

Air filtration can’t fix the person who sits in front of you.

No matter how well plane air filters work, they can’t help you if air with virus in it gets to you before it gets to the filters. If you’re sitting in the same row with someone who’s infected, or just in front of or behind someone who’s infected, that’s what’s almost certainly going to happen. It doesn’t mean you’ll necessarily get infected, but you’ll be exposed.

So how do you keep yourself COVID-safer on a plane? You know the drill by now, right?

Wear a mask. The better the mask, the better your protection — against respiratory viruses in general, not just COVID-19.

I wore my KN95 mask on my flight, and I kept it on — even after we “blasted off,” except for brief moments when I took a sip of water. Was it the most comfortable thing in the world? Of course not! But neither are airplane seats, or standing in line waiting to get through security. They’re just part of what we all deal with as we travel to our destinations — as safely as we can.