Humans harbor diverse microbial communities in and on our bodies
, and these can be readily detected in the built environment. Human-associated bacteria disperse into and throughout buildings by three primary mechanisms: (1) direct human contact with indoor surfaces; (2) bioaerosol particle emission from our breath, clothes, skin and hair; and (3) resuspension of indoor dust containing previously shed human skin cells, hair and other bacteria-laden particles. Microbial communities in the built environment are often traced back to an individual person, based on their direct contact with an object, including classroom surfaces
and mobile phones
. Using our unique Climate Chamber, we measured the airborne bacterial emissions, or “microbial cloud
“, of individuals. Most occupants could be clearly detected by their cloud or by settled microbial particles within 1.5 – 4 hours. Our results confirm that an occupied space is microbially-distinct from an unoccupied one, and demonstrate for the first time that individuals release their own personalized microbial cloud.