A new study published online this week in the journal PeerJ has found that humans emit their own personal microbial cloud (airborne microbes we emit into the air).

To test the individualized nature of the personal microbial cloud, scientists sequenced microbes from the air surrounding eleven people in a sanitized experimental chamber.

The team, headed by Dr James Meadow of the University of Oregon, found that most of the participants sitting alone in the chamber could be identified within four hours just by the unique combinations of bacteria in the surrounding air.

The results were driven by several groups of bacteria that are ubiquitous on and in humans, such as Streptococcus, which is commonly found in the mouth, and Propionibacterium and Corynebacterium, both common skin residents.

While these common human-associated microbes were detected in the air around all people in the study, the team found that the different combinations of those bacteria were the key to distinguishing among individual people.

“We expected that we would be able to detect the human microbiome in the air around a person,” Dr Meadow said.

“But we were surprised to find that we could identify most of the occupants just by sampling their microbial cloud.”

“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.”

The findings shed light on the extent to which we release our human microbiome to our surrounding environment.

The results also suggest potential forensic applications, for example to identify or determine where a person has been, though it is unclear whether individual occupants can be detected in a crowd of other people.

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Meadow J.F. et al. 2015. Humans differ in their personal microbial cloud. PeerJ 3: e1258; doi: 10.7717/peerj.1258