More than 37 million bacteria are stirred up by humans every hour inside a single room, according to a new study conducted by researchers from Yale University.

The researchers found that more than 37 million bacteria were stirred up every time someone entered the room. Majority of the bacteria were already present in the room, left by previous occupants and had settled on the floor.
“We live in this microbial soup, and a big ingredient is our own microorganisms. Mostly people are re-suspending what's been deposited before. The floor dust turns out to be the major source of the bacteria that we breathe”, Jordan Peccia said.
Source-Medindia