MANHATTAN — The Department of Homeland Security released a "harmless gas" and "nonhazardous" particulate matter in Grand Central Terminal on Monday morning as part of a weeklong study of airflow in the city's subway system.
"The main thing that we're looking for is to understand how particles travel, that has not been done in the subway before," said Don Bansleben, Program Manager with the Department of Homeland Security Chemical and Biological Defense Division.
The particles are made of an FDA-approved maltodextrin sugar and synthetic DNA fragments, which are so small that they are not regulated by government agencies, Bansleben said.
They plan to release the gas and "particle tracers" on the uptown platform for 4, 5 and 6 trains at Grand Central at 11 a.m. every day this week, as well as Monday-Wednesday on the 1, 2 and 3 platform in Times Square and Thursday and Friday on the A, C and E platform in Penn Station.
After the gas and particles are released, they will travel through onto the trains and through the tunnels. But riders will not realize they're present. After the particles in gas are released, they are not visible and carry no scent.
To analyze the results, the Bansleben said that DHS has equipment set up at 60 stations in Manhattan, three in Queens, one in Brooklyn and one on the Path train platform. An analysis will take months he said.
The gases used in the study, perfluorocarbons, "poses no risk to the public," Homeland Security officials said.
An official with the FDNY stressed that there is no imminent threat, but that the study is a precautionary measure that will help government agencies react to a biological or chemical attack in the subway, or to natural threats like the Zika Virus or Ebola.
"This has a capability for a lot of different issues, not only evacuation, but also the recovery of these types of facilities so we can move people back into them and know that it's safe," said Bob Ingram, Battalion Chief for the FDNY Center for Terrorism and Disaster Preparedness.
