New York subway undergoes bio-terror experiment: DHS

A woman walks by a device used for chemical tracers used by the Department of Homeland Security and New York Metropolitan Transportation Authority during a test of how gas would flow through the subway system in New York, US, May 9, 2016. (Reuters)

The New York City has released an odorless gas into the subway to experiment an instance of a bio-terror attack.

Three of the busiest stations underwent the Monday experiment, which included a combination of odorless, inert gases, and tracer materials, said officials with the US Department of Homeland Security.

Apart from Grand Central Terminal, Times Square, and Penn Station, 55 other stations are set to take air samples through newly–installed equipment every four hours to check out how the gas spread.

"These tests are designed to gather data about how airborne  material will travel through subway systems and the trains and how quickly they will move," said John Verrico, a spokesman for the department's Science and Technology Directorate.

The initiative, part of a project that kicked off in 2012, led to mixed feeling among commuters, according to Reuters.

"It's something that we know is a possibility but we don't want to think about it because we don't want it to become a reality," said Doris Altman, a New York City subway commuter. "But it's really frightening."