The U.S. Department of Homeland Security (DHS) and the Massachusetts Bay Transportation Authority (MBTA) have partnered on a new DHS Science & Technology Directorate-led study that will examine the behavior of airborne contaminants if they were to be released into the subway.

“Proactively studying and preparing for possible threats is one of our most effective strategies for fortifying our critical infrastructure,” said Secretary of Homeland Security Janet Napolitano. “This study is one of many efforts the Department is undertaking across the country to inform our emergency response planning in preparation for chemical or biological terrorist attacks.”

“This project — combining the resources and expertise of scientists from around the world — will refine best practices for responding to the release of toxic gas or chemicals in public transportation systems,” said Under Secretary for Science & Technology Dr. Tara O’Toole.

The study will involve the release of common, harmless tracer gases used for indoor and outdoor air testing; an inert particle tracer tagged with a biologically inert, non-toxic organic dye used in medical imaging applications; and a common optical brightener often used in laundry detergents and paper manufacturing.

“We appreciate the opportunity to work with DHS on this initiative,” said MBTA Transit Police Chief Paul MacMillan. “This study will help the MBTA make informed decisions regarding the safety and security of its passengers.”

The study will help scientists understand the airflow characteristics for smoke or unintentional spills of chemicals or fuels — providing data that will help guide the design of next generation detection systems and enable transportation systems to strengthen evacuation, ventilation and other incident response strategies.

Particle and gas concentrations will be sampled in more than 20 stations and in subway cars in the underground portion of the MBTA subway system from Dec. 5 to 11. Although commuters may notice the presence of equipment and researchers, the study will not disrupt normal activities or inconvenience the public.

The research team will include scientists from Argonne National Laboratory of Argonne, Ill.; Lawrence Berkeley National Laboratory of Berkeley, Calif.; ICx Technologies of Arlington, Va.; Defence Science and Technology Laboratory of the United Kingdom; and Chemistry Centre of Australia.

Critical infrastructure and key resources (CIKR) include physical and digital assets, systems and networks that play significant roles in America’s safety, economy and public health. Their incapacitation or destruction could debilitate the overall stability of the U.S. and threaten national security.

CIKR is comprised of 18 unique sectors. The sectors represent key areas such as transportation and communications systems, food and water, manufacturing, energy, and emergency services. DHS coordinates security efforts with the full range of CIKR partners — state, local, tribal, territorial and private sector — via a network of Government and Sector Coordinating Councils.