It's such a unifying question. Whenever you've been on the subway and you grab something  and you're like, "oh, that's wet, and that's weird" or you sit somewhere and the seat is still warm, and you know it's just warm, but it still feels weird.

I think the interesting thing is that people base their fear on ignorance and they don't know what's there, and I so I want to try to show that what's there is mostly what you'll find on other surfaces. So Pathomap is a project to examine the longitudinal microbiome, or the bacteria, on the surfaces across the New York City Subway system.

We wanted to look at just what's there and no one really knew, so we just started swabbing and then sequencing everything we could see. We did the train, and then two places at the station, usually a bench or the turnstiles, or the garbage cans, or the kiosks. This covers all approximately 656 miles of the New York City Subway system, and all of the over 30,000 different sort of turnstiles.

One of the real goals is to know real well what baseline and normal looks like, so if we did see an aberrant species or bacteria, we could know that it is different enough to be able to react to it. But the obvious application of it would be for bio-defense, or for tracking infectious disease. We could really respond quickly, and potentially quarantine an area, prevent other people from getting sick, not only in the city, but also in the airports, places like that.

We found things like enterococcus physalis, what could be commonly associated with a fecal bacteria, as well as things like staff and strep, things you would normally hear of and think, "oh no, I don't want that."

But we've also seen some very good actors, like lactobacillus-type strains, things you would find in yogurt, that are normal, sort of bacteria in your mouth. So, you can find some things that are very, very good, and things that could be potentially bad.

The subway is a mirror of humanity's surfaces, so there's both an angel and a demon on every surface.

The subway gets cleaned and essentially gets washed away. So it's almost like the forest gets cleared, and then the morning commuters come and drop their seeds and by the afternoon, there's a whole forest again that's re-sprouted of whatever people left behind.

The subway is us, it's coming from all of us, so if you just rubbed all of the subway surfaces, it'd be akin to rubbing all of the people that walk through it. Which on the one hand is a little bit terrifying and gross, but on the other hand is this interesting humanistic view that we're all in this together. We're all in the same big Petri dish. But as long as you don't have any open wounds, and you wash your hands, you'll be just fine, and even if not, you'll probably just be fine.