“Your tray table is the least hygienic part of a plane,” Abbamonte says. “I suggest bringing anti-bacterial wipes and wiping them down if you plan to use them along with your armrest, etc.,” he adds. During an experiment, microbiologists found more than 3,000 bacteria on a plane. The next filthiest place is everything inside the seat pocket. The overhead air vents are among the worst offenders, too.