The dirtiest parts of the airport are the security line trays
Thanks to work carried out by a team of researchers from the University of Nottingham, we now know that the security-line trays used to transport bags, loose change, bottles, and laptops through X-ray machines are the grimiest surfaces in airports—more so than toilet bowls, even.
The team’s research involved swabbing and collecting 90 surface samples and four air samples in the Helsinki-Vantaa airport in Finland over the course of several weeks.
Quartz
https://qz.com/1395922/the-dirtiest-parts-of-the-airport-are-the-security-line-trays/