Professor William Nazaroff, faculty member in the environmental engineering program, is part of the research team studying the association of human occupancy and substantially increased airborne concentrations of bacteria and fungi of various sizes.
This is the first time that anyone has quantified emissions of bacteria and fungi associated with human occupancy using modern DNA-based analysis methods. (In that respect, the work is far superior in providing a complete picture of what's there to prior, culture-based analysis methods.)
Nazaroff says, "Whenever you share occupied indoor spaces with others, you are exposed to bacteria and fungi associated with other current and recent occupants. We have clues about factors that might influence levels; for example, higher occupant density implies greater exposure. However, we don't yet know whether there is any health significance associated with routine bacteria and fungi exposure indoors."
See With You in the Room, Bacteria Counts Spike -- By About 37 Million Bacteria Per Hour (Science Daily)