An alarming new study claims that you are better off not using those hand dryers in public bathrooms, because they may actually be making your hands dirtier. The study, published in the journal Applied and Environmental Microbiology, determined that hot air hand dryers spread around all the bacteria that gathers in the bathroom despite the fact that they often advertise how hygenic they are.

The problem is that while hand dryers may indeed allow people to avoid touching more surfaces when drying their hands, it is negated by the fact that the air simply redeposits the bacteria all around the bathroom, scientists say. As a result, these hand dryers can cause disease and infections for some people, they warn.

The study examined 36 men’s and women’s bathrooms at the University of Connecticut School of Medicine and held up test plates to hand dryer air, where they found as many as 60 different colonies of bacteria while air drying for 30 seconds. The air itself that comes from the dryers is clean, it is the rest of the bathroom air that it pushes around that is not.

“Plates exposed to hand dryer air for 30 s averaged 18 to 60 colonies/plate; but interior hand dryer nozzle surfaces had minimal bacterial levels, plates exposed to bathroom air for 2 min with hand dryers off averaged ≤1 colony, and plates exposed to bathroom air moved by a small fan for 20 min had averages of 15 and 12 colonies/plate in two buildings tested,” reads the abstract from the paper. “Retrofitting hand dryers with HEPA filters reduced bacterial deposition by hand dryers ∼4-fold, and potential human pathogens were recovered from plates exposed to hand dryer air whether or not a HEPA filter was present and from bathroom air moved by a small fan.”