There's alot of behind the scenes going on in regards to airborne pathogens in a hospital. I know a guy one of his jobs at a hospital is to go around with a handheld machine looks like a BBQ pit lighter. It's a smoke machine and he goes around testing doors to make sure the negative or positive pressure is working. He has an infection control shirt on cause people were thinking he was taking pictures or something by sticking the machine at the bottom of patient doors. He said he has to show the machine all the time.