Government studies have debunked the long-held myth that air circulated in commercial planes is jam-packed with disease-causing germs.
Now comes a study that raises fears about germs on cabin surfaces.
Microbiologists and engineers at Auburn University found that disease-causing bacteria can live several days on armrests, tray tables, toilet buttons, window shades, seat pockets and seat leather.
The bacteria tested in the study include a type of E. coli that can cause diarrhoea in adults and a drug-resistant staphylococcus that can lead to infections, skin disease, pneumonia and sepsis.
Bacteria in saliva that researchers placed on seat pockets lived the longest - eight days, according to the study, sponsored by the Federal Aviation Administration.
The airline industry points out that their cabins are routinely cleaned.
"Airlines know that cleanliness of aircraft is important to customers when they make their travel decisions," said Jean Medina, a spokeswoman for Airlines for America, the trade group for the nation's largest airlines. "As such, airlines work continuously to keep planes clean."
You can at least breathe easier that the U.S. Centers for Disease Control and Prevention has already dismissed fears about diseases spread by air on commercial planes.
Newer planes recirculate up to half of cabin air with outside air and pass it through a series of high-efficiency particulate air (HEPA) filters, up to 30 times per hour, according to the CDC.
"As a result, the air cabin environment is not conducive to the spread of most infectious diseases," the agency says.