Human interaction includes contact with the bacterial universe of another person ejected into the air:

It’s like trespassing on private microscopic territory—it’s that personal.

A Unique Perfume-Cloud of Bacteria Follows You Wherever You Go — NOVA Next | PBS

Looks like we’re not that different from flowers after all. We each have our own odor “cloud” or headspace. Probably won’t be long before headspace technology can create a concentrated “Eau de You”!