Microbiologists find dirtiest things on an airplane and in the airport

A new study finds airports are breeding grounds for germs and bacteria.

Website Travelmath.com sent a microbiologist to find out just how dirty airports and airplanes can be. The microbiologist took 26 samples from five airports across the United States. The scientist also took samples from four flights by two major carriers.

PHOTOS: Six dirtiest spots on planes and in airports

After running the samples, researchers found tray tables were the dirtiest surface air travelers will encounter on their trip, with an average of 2,155 bacteria colony-forming units per square inch.

"Since this could provide bacteria direct transmission to your mouth, a clear takeaway from this is to eliminate any direct contact your food has with the tray table," the report suggests.

So why are they so dirty? The report says most tray tables are only cleaned thoroughly twice a day because airline staff often have little time between flights to give seats a proper cleaning. Places like restrooms, on the other hand, are cleaned multiple times a day.

There is some good news hidden in the study. Microbiologists say they did not find any fecal coliforms such as E. coli in any of their samples. Those types of bacteria are often infectious.

The report did not disclose which airports or flights were involved.

Tap through the photo gallery above to see the top six dirtiest spots.