If you’re the kind of person who avoids public bathrooms at all costs, you may feel validated, as well as disturbed, by a 2018 study from researchers at the University of Connecticut and Quinnipiac University. They suspected that hot-air hand dryers in public restrooms might be sucking up bacteria from the air, and dumping them on the newly washed hands of unsuspecting patrons.⁠ ⁠ To test this theory, scientists exposed petri dishes to bathroom air under different conditions and took them back to the microbiology laboratory to look for bacterial growth. Petri dishes exposed to bathroom air for two minutes with the hand dryers off only grew one colony of bacteria, or none at all. However, petri dishes exposed to hot air from a bathroom hand dryer for 30 seconds grew up to 254 colonies of bacteria (though most had from 18 to 60 colonies of bacteria).⁠ ⁠ _____⁠ ⁠ Were the bacteria multiplying inside the hand dryers, or were they being pulled into the hand dryers from the air inside the ba...