Trip planning website Travelmath sent a microbiologist to test five different airports and four different flights on two major airline carriers. The samples were sent to a lab to estimate the total bacteria population per square inch. The values, in colony-forming units (CFU), are the median of the tests.

The result may surprise you. The toilets aren't the dirtiest places on the plane. It's the trays! They had more bacteria than toilet flush buttons and seatbelt buckles. The second most dirtiest were the drinking fountain buttons, followed by overhead air vents. 

Thinking of canceling your flight? Don't! None of the samples from airports and airplanes tested positive for fecal coliforms like E. coli. At least something.