This morning, the NYPD flooded the New York subway system with an odorless, invisible gas. The simulated terror attack is part of a three-day test that will generate a map of how air flows through the subways, helping emergency responders if a real airborne toxic event ever occurs.


The NYPD is working with Brookhaven National Laboratory, a Long Island-based lab, which will handle the actual dispersion and tracking of the gas. Funded by a $3.4 million Department of Homeland Security grant, the project will release small amounts of Perfluorocarbon tracers—an odorless, invisible, and non-toxic gas—throughout roughly 200 subway stations.

We interviewed Brookhaven's Paul Kalb, the principal investigator of the study, about the tests back in April. Here's what he had to say:

The study will show us the worst case scenario. It'll be a close representation of how particles from a bioweapon or dirty bomb could move through the air. [...] Anything on the surface can get sucked down into the subway through air grates. And likewise, anything on the subway eventually makes its way to the street.


The movement of the PFTs will be tracked thanks to small, featureless meters installed in select stations this morning by Brookhaven interns (of course). From there, scientists will be able to generate a "plume model" of how gas moves through the complex subway system—which, eventually, will be used to inform decisions made by first-responders during a real attack.

Lead image by Stuart Monk/Shutterstock.