Be careful what you touch the next time you're traveling by air.

In an admittedly unscientific test conducted for the website over the holiday season – six kinds of surfaces from three major U.S. airports or three flights — the results show some significant levels of bacteria.

At the airports, researchers swabbed self-check-in screens, armrests on the chairs near airline gates, and buttons on water fountains.  The samples were then sent to a lab to determine the average number of viable bacteria and fungal cells per square inch, or colony-forming units (CFU).

The self-check-in screens averaged more than 250,000 CFU.  To put that in perspective, the average bathroom doorknob has about 200 CFU, a toilet seat about 170.

Armrests on chairs near boarding gates were found to have more than  21,000 CFU; water fountain buttons registered about 19,100. The level for a home kitchen sink — typically the most contaminated place in a home? Also about 21,000.

In flight, researchers inspected   lavatory flush buttons, tray tables, and seat belt buckles.

Not surprisingly the flush buttons registered the highest number – but nowhere near the level of the airport check-in screens – at more than 95,145 CFU. In comparison, the typical handle on a home toilet registers 30 CFU.

The tray tables measured about 11,500 and seat belt buckles 1,100.  Kitchen countertops average of 360 CFU and cutting boards 45.

Though not all bacteria are harmful,   gram-positive cocci  —  often the cause of pneumonia; skin, ear, and sinus infections; food poisoning; meningitis; and toxic shock syndrome — was found on all of the tested surfaces. The greatest percentages turned up on lavatory flush buttons (82 percent) and tray tables (65 percent).

"It's often thought airplanes are cleaned between each flight, but the FAA actually doesn't regulate or inspect aircraft cleaning," states the report. "Each airline can decide how often and how well an airplane is cleaned."

A short turnaround time between flights could affect how well the plane is cleaned.

The report additionally states that when planes are cleaned, typically only general cleaners are used, not strong disinfectants.