Think twice before you nibble on that cracker that fell on your tray table.
Whether you’re a frequent flyer or a once-a-year traveler, chances are you’ve been grossed out on an airplane a time or two. It’s pretty nasty to find someone’s curdling coffee or half-eaten bagel in the seat pocket in front of you. Airports and airplanes in general are notoriously dirty, but there are certain locations that are ickier than the rest.
To find out where the dirtiest spots were located, Travelmath—a site that makes travel-related calculations—turned to a microbiologist for some answers. After taking samples from five airport locations and four different flights, the microbiologist determined the number of Colony Forming Units (CFUs) per square inch, which Travelmath then used to create a ranking of the areas with the most germs.
Here are their results for the dirtiest locations on an airplane:
Surprisingly, tray tables—not bathrooms—were far and away the dirtiest spots on a plane, followed by the overhead air vents. Coming in third was the lavatory flush button and, finally, the seatbelt buckle.
In the analysis, Travelmath explains why these results may differ from our initial expectations. Over the past few years, planes have started to board and offload flights faster than ever. As a result, tray tables are often only cleaned at the end of the day, especially since there are no federal regulations that require otherwise. In contrast, most flights have regular cleaning schedules for bathrooms. In trying to curb the spread of fecal bacteria, airlines seem to be neglecting other areas of the plane.
In fact, bathrooms didn’t rank as the dirtiest location in airports, either. Instead, the study found that drinking fountain buttons had almost 18 times as many germs as bathroom stall locks:
To give you an idea of just how dirty these locations are, Travelmath compared their results to various household items that had been tested by the National Sanitation Foundation. All of the locations on airplanes and in airports were dirtier than money or cell phones. With the exception of bathroom stall locks, these locations were also dirtier than the average home toilet seat, which has only 172 CFUs. Surprisingly, the study found that most locations on an airplane were cleaner than home countertops (361 CFUs), and significantly cleaner than pet toys (19,000 CFUs) or pet bowls (306,000 CFUs).
Of course, the cleanliness of a plane or airport depends on where you are. Some airports are far more sanitary than others. According to the 2015 World Airport Awards, the cleanest airports in the world were located in South Korea, China, Japan, and Singapore, with the Icheon airport in South Korea taking the top spot. The top ten cleanest airports also included destinations like Zurich, Copenhagen, and Helsinki.
Clearly, American airports and planes need to step up their game when it comes to cleanliness. But at least they can take comfort in the fact that they’re not nearly as dirty as your household pet bowl. Seriously, give that thing a good scrub.