Skip to main content
ABC News
Listen To Our Conversation With The Microbe Map Man

Have you seen the microbe map? At this point, if you’re a New Yorker, your Twitter feed has probably picked over it, your friends have probably emailed you, and you can soon expect a call from your mom worrying about the map of germs found on the city’s subway system. Christopher Mason, a doctor and professor at Weill Cornell Medical College, and his team spent 18 months swabbing turnstiles, benches and poles1 in New York’s 466 subway stations. They found genetic material from 15,152 species.

Mason visited the FiveThirtyEight studio to talk about the findings, the maps the team created and why the research is getting so much attention.

Listen to or download the interview via the player above. And see the team’s map, and highlights from the conversation, below.

Heat map analysis of bacteria in New York City subway stations.

Heat-map analysis of bacteria in New York subway stations.


On the huge public reaction

Jody Avirgan: I suspect that what you were trying to say was, “Look at the stuff around us — and we’re fine!” And instead people are saying, “Oh, my gosh, look at the stuff around us.”

Mason: Right. Look at these things that are in one out of 1,500 samples and barely detectable. That has not been part of the mainstream reporting in most outlets. But it is unquestionable — these data show that most things are not at all to be worried about.”

On learning about what we don’t know

“Forty-eight percent of all the DNA under our fingertips is unknown. It doesn’t match any known organism. It represents a large amount of discovery still to do. 5.5 million people touch railings every day. There’s a lot to discover. We also saw that human ancestry can look like demographic data, and even molecular echoes can persist at different stations.”

The “molecular echo” in every subway station

“We can see what types of genes people leave behind on the surface, and we can see if that matches the historical ancestry population patterns from different people in different areas of the world. What’s left on the surface is a molecular echo of who’s been through there.”

Taking the show on the road

“This is the first time a city’s been profiled at a molecular level. So, we in some ways have no idea yet how this compares to D.C. — also in D.C., you can’t eat on the subway. Will we see less of these other trace elements that are associated with food in there? That’s a hypothesis that we’re looking at. We started a campaign to begin doing swabbing, we have cultures being grown in Shanghai, in Tokyo … we’re doing some in Sao Paolo, some in Paris. The goal is to come to build the context of how New York compares to other cities. What happens when you build complete molecular profiles of other cities?”

NYC’s benches vs. San Francisco’s cloth seats

“We know that wood surfaces absorb a little bit more DNA. We saw more coming from wood surfaces. And the MTA has been replacing most of their benches with metal, which may be less comfortable but I can tell you they’re harboring less bacteria, or at least less DNA. … I think cloth is probably not the best thing to put in a subway system, so I’m glad that New York does not have that.”

Anthrax and the plague are just a best guess

“We say that in the paper very explicitly. We even assume that as time goes on, some of these fragments of DNA will find a better ‘home,’ if you will, and find a better match.”

What’s new here?

“If you ask any environmental ecologist about these results, not one of them is surprised. But if you ask an infectious disease expert, they’re all shocked.”

(This is part of the prelaunch experimentation for the FiveThirtyEight podcast. We’ll be posting audio of different kinds on SoundCloud and then launching the actual podcast this spring. Stay tuned! And let us know what you think by tweeting our podcast producer/host, @jodyavirgan, or emailing us.)


  1. We learned that his team found the most microbes on the “top bar” in the subway cars. So, if you need to stabilize yourself, reach for the vertical pole.

Jody Avirgan hosts and produces podcasts for FiveThirtyEight.