Keep your air vents open. Leaving vents open and allowing air to flow can help prevent the spread of bacteria and viruses, although closing your vents isn’t necessarily a deal breaker because the air inside a plane is constantly being refreshed. According to the International Air Transport Association (IATA) website, “cabin air is refreshed 20-30 times an hour, about 10 times more than most office buildings.”
All that said, there’s certainly a chance of bacterial and viral spread within the cabin before the air is sent through the HEPA filter and blended with fresh air — that is, from person to person within the cabin, especially if your seatmate is coughing or sneezing. And that’s one area where the vents can prove helpful.
The flow of air in a plane cabin goes from top to bottom, not from front to back or vice versa.
With that in mind, keeping your vents open will help keep the air moving from top to bottom quickly. But that’s not the only thing you can do to reduce the risk of transmission.
Related: Why You Should Always Choose a Window Seat on a Plane During Flu Season
Beyond that, you should keep in mind that some areas on planes can be incredibly dirty — HEPA filters won’t remove the germs left on surfaces like armrests and tray tables, so it’s a good idea to wipe down all hard surfaces in and around your seat.
There’s also the consideration of boarding and deplaning. Air filtration systems are not always turned on while the plane is on the ground — that’s why planes can feel quite stuffy while they’re parked at the gate. So if you’re looking for an extra level of safety, you might want to consider masking up during boarding and deplaning, too. Then once you’re in the air, open up that vent to increase the airflow around you.