If you’ve ever found yourself feeling ill after a flight, those surrounding you in the security line may be to blame. It turns out that the security trays may be the dirtiest part of the entire flying experience, thanks to high volume of people and possessions using them each day. Scientists from England’s University of Nottingham and Finland’s National Institute for Health and Welfare conducted tests on the plastic trays flyers use to send their possessions through the security scanner at Helsinki Airport. Their discoveries are quite shocking, particularly if you’re a diligent germaphobe. The New York Times reported that the scientists discovered traces of multiple viral diseases on half of the trays surveyed in the study.

During the study, which took place during the winter of 2016, frequently touched surfaces at the airport were swabbed both during and after the airport’s busiest flying hours. But the dirtiest part of the flying experience appears to be the security trays, where traces of rhinovirus, the source of the common cold and the influenza A virus, were found. “At Finavia airports, the hygiene protocols are carried in accordance to health officials’ requirements — all surfaces are cleaned daily and all security checkpoint trays, etc., are washed regularly,” said Finavia, the company that operates Helsinki Airport, to the Times in an email.

While you certainly can’t control the hygiene habits of your fellow passengers, this news at least confirms the importance of following basic sanitation and cleanliness practices. Germs are everywhere, but there’s no guarantee that the unavoidable process of passing through security before your flight will result in you catching a cold. Just be sure to hit the restroom and wash your hands before settling in at the gate.

H/T: The New York Times