Airline crews do their best to sanitise the plane, but there are still things on a plane that don’t get cleaned as well as they should. “The tray table is notorious,” says professor of epidemiology, Stephen Morse. “Those tray tables are used for all kinds of things,” adds Ferguson. “During flights, I’ve seen parents changing babies on top of tray tables. I’ve seen people put their bare feet on top of tray tables.” One study found that trays harbour an average of 2155 colony-forming units of bacteria per square inch. Compare that with the 265 units on the lavatory flush button. And while all samples tested negative for potentially infectious bacteria such as E. coli, you’ll still want to steer clear of that tray. An extra safety tip in the time of COVID-19: wipe down your tray table and any other surfaces with disinfectant wipes before using.