From obsessing over recycled cabin air to worrying about potentially contaminated coffee or tea, flying isn't fun for germophobes. Now, Lonely Planet reports that travelers who opt for self check-in should consider breaking out the hand sanitizer before they even hit security.

In late 2017, the team at website insuranceQuotes checked out three major U.S. airports, as well as the planes used on several flights, to gauge which areas were the most germ-filled. They conducted 18 swab tests across six surfaces (including airport water fountains and plane armrests), then used lab analysis to measure the average number of colony-forming units (CFU), a standard measurement for the number of viable bacteria and fungal cells per square inch of a surface area.

Self check-in kiosks were the germiest surface, according to lab findings. The average kiosk screen contained 253,857 CFU, with one kiosk recording over 1 million CFU. Bathroom flush buttons were, surprisingly, quite a bit cleaner (although not that clean), with an average of 95,145 CFU. Other particularly germy spots included the bench armrests at airline gates (21,630 CFU on average), water fountain buttons (19,181 CFU on average) and airplane tray tables (11,595 CFU on average).

To put their results in perspective, insuranceQuotes provided the average CFUs for household objects and appliances like kitchen sinks (21,000 CFU), bathroom doorknobs (203 CFU), and toilet seats (172 CFU). For the most part, these levels were far lower than the ones found in airports and on planes, as you might expect when comparing public spaces to private homes.

But this report shouldn't plunge travelers into full-on Howard Hughes mode. For one thing, the tests were performed by an insurance company, not a team of trained scientists. And at the end of the day, not all germs are actually bad for you. As humans, we have trillions of microbes living both on us and inside of us. Some of these microbes are beneficial, and can even kill disease-causing bacteria. Exposure to some bacteria can even strengthen our immune systems.

Still worried? While flying, just remember to be careful where you put your hands, stash a travel-sized bottle of Purell in your carry-on, and follow other preventative tips for avoiding germs in transit.

[h/t Lonely Planet]