Given tens of thousands of people from all over the world stream through every day, it's little wonder airports are cesspools of germs.
So researchers set about determining which specific parts of the airport are the biggest havens for bacteria and fungi — and the top culprit isn't necessarily what you might expect, news.com.au reports.
As part of the research, which was commissioned by insurancequotes.com, swab tests were conducted on various surfaces at three major airports in the United States.
The samples were then analysed to determine each surface's average colony-forming units (CFU) of bacteria per square inch.
The higher the CFU number, the germier the surface was.
As a comparison, the researchers said the average CFU on a toilet seat was 172. A bathroom doorknob had 203 CFU. Both were pretty germy — but that was nothing compared to what else they found.
The communal water bubbler at the airport terminal — where countless people have pressed their lips right up against — had 19,181 CFU on the button, according to the study.
The armrest on the benches at the airport gate was found to have 21,630 CFU.
But the absolute germiest part of the airport was found to be the self-serve check-in computer screens, which harboured a toe-curling 253,857 CFU of bacteria.
That's more than 10 times the amount of bacteria found on the disgusting communal bubbler.
Even more unsettling: one of the screens tested by researchers recorded more than one million CFU alone.
The research team carried out similar studies on surfaces on aeroplanes, and found while the bacteria levels were a bit lower than at the airport, they were still a lot worse than a toilet seat.
The flush button on the plane toilet had an average of 95,145 CFU.
The tray table had 11,595 CFU, and the seat belt buckle had 1116 CFU.
The researchers' report noted it was up to individual airlines to manage how their aircraft were cleaned, and cleaning wasn't regulated by a federal authority.
"Each airline can decide how often and how well an aeroplane is cleaned, so if the turnaround time between flights is low, the plane may not be cleaned at all," the report read.
"Even when a plane is cleaned, general cleaners are used rather than stronger disinfectants, leaving dangerous germs right in your lap."
Researchers also narrowed down the top varieties of bacteria and fungi detected in the swab studies.
There were five key forms: Gram-positive rods, which can be helpful but also pathogenic; Gram-positive cocci, associated with infections like pneumonia and toxic shock syndrome; Gram-negative rods, associated with hospital-acquired infections; bacillus, which included the bacteria that caused food to spoil; and yeast.
Many of the surfaces had a combination of those bacteria and fungi present.
Harmful Gram-positive cocci was the main germ found on the aeroplane toilet flush button, the tray table, and the self-serve check-in screen.
The report recommended a couple of ways to avoid the harmful effects of germs.
"Opting for the faster route may be logical if you're short on time or just hate waiting in lines, but be cautious of the risk," the report said.
"Carry sanitiser with you when travelling, or one of the millions of germs you come in contact with may have you exchanging vacation days for sick days."
The researcher's results came as woman carried out an unrelated DIY experiment on a hand dryer at an airport, with stomach-churning results.
American woman Nichole Ward shared a picture of a Petri dish on Facebook, which she claims to have held under a Dyson Airblade for three minutes and left to "incubate" for 48 hours.
She wrote: "OK guys ... ready to have your mind blown?!"
"This here, is what grew in a Petri dish after just a few days," she says, showing an image of the Petri dish with all sorts of gross funk inside.
"I stuck the open plate in an enclosed hand dryer of a public bathroom for a total of three minutes. Yes 3 only. DO NOT EVER dry your hands in those things again," Ms Ward said.
"This is the several strains of possible pathogenic fungi and bacteria that you're swirling around your hands, and you think you're walking out with clean hands. You're welcome."
It was unclear what sort of scientific background Ms Ward had, if any, to make her assessment — and Dyson said it was "surprised" by the results, noting it was "unclear on the methodology employed".