Federal officials are working with the MBTA to protect the city from a chemical or biological terror attack.
Transit officials said today that riders should not be alarmed if they spot scientists in fluorescent-orange vests poking around the transit system this week, because they're here to release and trace the movement of nontoxic, odorless gases and particles as part of an ongoing effort to keep riders and residents safe from chemical and biological agents.
The Department of Homeland Security experiment simulates how contaminants might move through the subway in a chemical or biological terrorist attack. The air is collected and measured by clearly marked, "highly visible" boxes throughout the transit system.
In 2009 and 2010, similar studies examined the subway's airflow, but this time the tests look at how gas and air particles could waft out of underground tunnels and stations, and into city streets.
"We want to build on the experiments we’ve done in the past; we want to understand how an event might impact the surrounding city center," said Department of Homeland Security Science and Technology Directorate program manager Teresa Lustig yesterday.
Transit police said the study will help shape long-term tactics on how to handle a chemical catastrophe.
"This will ultimately help us enhance our emergency response plans. Most importantly, it will help us fine tune our evacuation plans," said MBTA Deputy Chief Lewis Best, who oversees the T's homeland security and emergency preparedness.
Near the site of their release, the clouds of gas and particles may appear as a fine mist, officials said, but may also be invisible.
Regardless, the gas poses no threat to riders.
The testing, which will continue through the end of the week, is being done at off-peak hours and should not disrupt commuters.