You might blame your pets for shedding all over the house. But we humans do it too—and our stuff is alive. "We're constantly emitting microbes around us. And this is coming from shedding of our skin, from exhaling, our hair, we're just full of these guys." Adam Altrichter, a microbial ecologist at the University of Oregon. "We've never been sterile organisms. We are definitely masses of microbes both in and on us."

If you're picturing the Peanuts character Pig Pen, you may not be far off. Because biologists estimate we shed a million particles an hour—including, of course, a lot of bacteria. Altrichter and his colleagues wanted to measure that cloud of particles—the "Pig Pen" effect, if you will—so they asked 11 volunteers not to shower, dressed them in shorts and tank tops, and put them in a sterile chamber for hours at a time, while collecting microbial samples on surfaces and in the air.

What they found in those samples was a menagerie of bacteria from the volunteers' skin, guts, genital tracts, lungs, noses and mouths. And for eight of the 11 study subjects, the microbial cloud was unique enough to identify the individual who'd left it—suggesting that this bacterial 'fingerprint' could someday be used in forensics. The study is in the journal PeerJ. [James F. Meadow et al, Humans differ in their personal microbial cloud]

Given that we spend 90 percent of our lives indoors, our microbial clouds also colonize the places we live and work—and, yes, the people around us. "And so it's just kind of interesting to think about how the people that we interact with at work, or in classrooms, or in other environments, how we could be sharing some of these microbial passengers between us, not even knowing anything about it." And now that you do know about it—hopefully your view of your coworkers won’t become…clouded.

—Christopher Intagliata

[The above text is a transcript of this podcast.]