The germiest thing at an airport isn’t a toilet. What it is may surprise you.

As if zig-zagging through the airport security line wasn’t stressful enough, now travelers have another reason to dread those check points.

A new study found that half of the plastic security bins tested at one European airport were contaminated with viruses that cause colds and flu. So while passengers are dumping their shoes, cell phones and other personal belongings into those bins, they very likely are coming into contact with germs that could make them sick.

In conducting the investigation, researchers collected surface and air samples at Helsinki-Vantaa Airport in Finland during the winter of 2016. In all, they collected 90 surface samples and four air samples, and they published their findings in BMC Infectious Diseases.

In addition to collecting samples from the plastic bins, the surfaces they tested in the airport included handrails of stairs, the divider glass at a passport control point and a plastic toy dog in a children’s play area. They detected more respiratory viruses on the toy but concluded that the bins pose the highest potential risk because almost all passengers come into contact with them.

They also tested a variety of toilet surfaces, including the lid, the flushing button and the lock on the door inside the stall. Interestingly, they detected no respiratory viruses on any of them or on elevator buttons, the touch screen on a check-in machine or the armrests of chairs in a waiting area.

Why are the plastic bins more likely to harbor germs than toilets are?

“I would suspect the bins are not cleaned as often, if they’re cleaned at all,” says Alla Gutina, an Advocate Nurse and infection preventionist at Advocate Good Shepherd Hospital in Barrington, Ill.

Gutina recommends traveling with hand sanitizer and washing hands frequently with soap and water at airports.

In addition to cleaning your hands often, Gutina offers these tips for helping to prevent the spread of germs:

• Avoid close contact with people you know to be sick with a cold or flu.
• Stay home when you are sick.
• Cover your mouth and nose when coughing or sneezing.
• Avoid touching your eyes, nose or mouth.
• Clean and disinfect frequently touched surfaces at home and work when possible.