Air dryers have been under the microscope for years because of their poor drying capability and “bug-blowback". They won the superficial argument of saving paper, saving trees, but ignoring the fact that they introduce a much costlier possible outcome of a foodborne outbreak. "Save a little lose a lot.”
“In most institutions, toilets don’t have lids and when you flush them you get a little bit of an aerosol,” said Dr. Peter Setlow, a molecular biology and biophysics professor at UConn Health. "So, where does that toilet plume go? The hand dryers grab that air in the bathroom and accelerate it,” Setlow said.
This study conducted by the University of Connecticut was published in Applied and Environmental Microbiology: http://aem.asm.org/content/84/8/e00044-18.abstract