Air Quality on Commercial Jets: How safe is the air on an airplane?
Most people assume that an airplane's cabin is like a cesspool of germs. A breeding ground for infection where one person's cold is recirculated throughout the entire passenger section. So you may be surprised to know that the air in a modern passenger jet is actually cleaner on average than the air in your office or local supermarket. Commercial jets utilize the same kind of high-efficiency particulate air filters that hospitals and OR’s use. These will remove almost all of the bacteria and viruses that may be living in the air.
“Air on an airplane is about half fresh and half recirculated, and that whole volume is changed out several times per hour,” says Patrick Smith, a longtime pilot and author of ‘Ask the Pilot.’ The combination of advanced filtration and regularly swapped out air supply makes for cleaner air than you'd get elsewhere. In fact, one airline study found that the time when air quality dipped the lowest was when the plane was parked on the tarmac with its doors open.
Airplanes are also designed to minimize airflow between cabins, so the sick person in first class is breathing entirely different air than someone in coach, or vice versa. When people claim to get sick after flying, this is likely a result of what psychologists call confirmatory bias: we notice times that we come down with a cold after a flight and remember these instances for longer because it fits this myth and confirms our beliefs, while we tend to discount times we fly and don't come down with a cold. Given how often people can come down with the sniffles, the law of averages would continually feed this belief. Or it may come from touching other dirty surfaces such as tray tables, lavatories, or shared arm rests. We may also catch colds from any number of other people we meet on the trip and falsely attribute it to the airplane.
So just wash your hands often and enjoy the flight. The air in the cabin is probably the least likely thing to get you sick.