Wipe down before getting too comfortable.

Johan Marengrd / EyeEm/Getty Images

As the holiday travel season approaches, consider making room in your carry-on bag for antibacterial wipes. The Canadian Broadcasting Corp.'s Marketplace sent a team of investigators out on 18 flights across Canada scheduled at various times of the day on Canada’s three major airlines—Air Canada, WestJet, and Porter. While they were onboard the planes, they swabbed everything from the seatbelts to the tray tables to the seat pocket and the bathroom door handle, collecting over 100 samples.

Once they were back on the ground, they sent the samples to a lab for testing and discovered that airplanes aren’t as clean as most travelers wish and hope. Out of all the places that were swabbed, nearly half contained levels of bacteria or yeast and mold that could put someone at risk for infection.

WATCH: Here’s The One Thing You Should Never Board a Plane Without

The most contaminated surface was a bit of a head scratcher. Literally. The investigation found that the headrest was uniformly the most germ-riddled surface, perhaps because it is simply not cleaned very often. They found staph and something called “hemolytic bacteria” on the headrest and the results were so surprising that even the expert Marketplace consulted was shocked by the outcome. "Honestly, I have looked at planes, and I travel so much on planes, I'm aware of so many of the different places [where germs could be found]," microbiologist Jason Tetro told the news outlet. "But then I saw what you showed me with the headrest. And even I, the germ guy, went 'ew.'" Unfortunately, a dirty head rest means that washing your hands won’t keep the germs at bay. It might be wise to make sure your carry-on bag includes antibacterial wipes to give the headrest a quick cleaning before settling in for the flight.

The second germiest place on the plane? The seat pocket in front of you. According to the flight attendants interviewed for the piece, the germs were not particularly surprising. During their time in the friendly skies, they have spotted travelers using the seat pockets as their personal trash bins and sticking everything up to and including dirty diapers in the seat pockets. That could explain why the testers found E. coli bacteria from fecal matter in some of the seat pocket samples. While traveling with an infant is a challenge and changing a diaper in the airplane bathroom is an acrobatic feat, using the pocket as an ersatz Diaper Genie isn’t fair to the flight crew, the cleaning crew, or your fellow customers. This is particularly true because E. coli bacteria can cause intestinal infections, with all the accompanying symptoms like diarrhea, vomiting, and abdominal pain. Bring a trash bag and stick dirty diapers in the bin where they belong.

Since humans can’t be trusted to have good manners or good behavior, when you travel, trust instead in antibacterial wipes and hand sanitizer.