[MUSIC PLAYING]
ROXANA HICKEY: When you're sitting
in this room as a participant, you're
hyperaware of how you're behaving.
You know, do I really need to scratch that itch?
Am I-- you know, am I going to run my hands
through my hair, am I emitting particles just by doing that?
LUKE GROSKIN: Roxana Hickey is not normally
a Guinea pig in an experiment.
As a microbial ecologist, she's usually the experimenter, not
the experimentee.
ROXANA HICKEY: Humans actually spend up to 90% of their lives
indoors.
And so the fact that we're being constantly exposed
to that environment is a good reason
to study what kinds of things we're contributing and picking
up from that environment.
LUKE GROSKIN: Things floating in the air
like bacteria and viruses, billions of organisms
all around you, all the time.
Being aware of them might make you a little self-conscious.
But for Roxana Hickey and the researchers
at the Biology and the Built Environment Center,
it's also a cause for celebration.
JESSICA GREEN: So we study the fate and transport
of microbes the way you would ecosystems, and to also
consider that they may not be necessarily harmful.
LUKE GROSKIN: Or exotic, either.
JESSICA GREEN: We saw that humans
were a very strong force in influencing what's going on
in the indoor environment.
And that pattern has emerged time and time and again.
LUKE GROSKIN: Just how big can our influence
be on the indoor microbiome?
To find out, you need a very large and very controlled
Petri dish of sorts.
ROXANA HICKEY: Right now we are sitting
in the climate chamber at the Energy Studies
in Buildings Laboratory.
So this room is a unique research tool
where we have the ability to control pretty much all
of the environmental variables that exist in here.
So temperature, relative humidity, air flow rate.
And that gives us a great opportunity
to be able to sample the particles that are surrounding
an individual in a room.
LUKE GROSKIN: You also need a good, clean-- or rather dirty
set of samples.
ROXANA HICKEY: The participants were
asked not to bathe or shower the morning of the experiment.
They were also asked not to apply
any products to their skin or wear perfumes or deodorants.
The participant walks in here, they sit down,
and then we just collect the air while they're waiting.
LUKE GROSKIN: And it doesn't take
much to get our microbiome airborne.
ROXANA HICKEY: On the human body,
we have trillions of bacteria inhabiting every environment.
For example, our skin.
We have a skin microbiome that is distinct from our gut
microbiome.
We have microbes in the urogenital tract.
We have them on our feet, our hands.
JESSICA GREEN: So if you touch a human being or you touch
a surface, then you can transfer your human microbiome
to that surface.
And then we are also directly shedding microbes
from our bodies.
So when your skin sloughs, for example, that's one mechanism.
It then gets suspended on our chairs, on our tabletops,
on the floor.
And then just by moving about, those end up getting
re-suspended and we're exposed in that way.
LUKE GROSKIN: And so by using this controlled chamber,
the researchers captured airborne microbes
on Petri dishes and sterile filters.
ROXANA HICKEY: So once we get them back to the lab,
we use a buffer to wash the cells of into solution.
And then we use that solution to extract DNA.
And we use that information and variations in that code
to determine what types of bacteria and fungi
we have in that sample.
LUKE GROSKIN: Revealing a very human picture.
ROXANA HICKEY: Even just the act of sitting there gives off
enough microbes for us to be able to detect
a person in a room.
LUKE GROSKIN: So we really are surrounded
by a microbial cloud.
What exactly is in that cloud?
ROXANA HICKEY: The main types of bacteria
that are found in the cloud are going
to be skin and oral associated microbes.
And so these would be things like staphylococcus,
Propoinibacterium, for instance.
LUKE GROSKIN: But that's not all they found.
JESSICA GREEN: We also, have time and time again,
seen a significant number of gut-associated microbes
in the indoor environment.
LUKE GROSKIN: But having so-called fecal bacteria
walking around you should neither surprise or alarm you.
ROXANA HICKEY: Most of the microbes
that are found even in our gut, in our urogenital tract,
those are healthy microbes.
We need those to be healthy.
And so the fact that they're everywhere is not alarming.
It's just part of the natural dynamics
of microbial communities on our bodies.
LUKE GROSKIN: What is surprising is how unique
our microbial impact can be.
ROXANA HICKEY: We can compare the particles that
are in the room when different individuals are
present at different times.
And their individual microbial clouds actually
are distinct from one another.
JESSICA GREEN: And that was a small sample size.
And we are now asking questions such as,
can you identify an individual out of a crowd?
ROXANA HICKEY: We're trying to understand
how far these particles actually move if a person is just
sitting in a chair.
Are the microbial clouds getting mixed together?
LUKE GROSKIN: How long do they last?
What activities effect them?
Can they change your own microbiome?
If sitting in a room by yourself,
pondering these questions, leaves
you feeling a little self-conscious,
you're not alone.
JESSICA GREEN: I am sitting in an ecosystem right now.
It's where I'm going to spend 90% of my life.
And I don't know anything about this ecosystem.
LUKE GROSKIN: For Science Friday, I'm Luke Groskin.
[MUSIC PLAYING]