Homeland Security to study dispersion of biological weapons in Boston subway

The U.S. Homeland Security Department has announced that it will release harmless gases and dye tracers into Boston's subway system next week to study the circulation of airborne contaminants through public transit networks in the event of a biological or chemical attack.

The planned study, which will examine how both smoke and airborne toxins move throughout the transit system, is expected to assist experts in developing future chemical-agent monitoring while also providing guidance for future improvements in air-purification systems, evacuation plans and emergency-response protocols for transportation systems.

"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," Janet Napolitano, Homeland Security Secretary, said in a statement.

The airborne contaminants study will run from December 5 through December 11. The Massachusetts Bay Transportation Authority will oversee the study, which will be conducted in more than 20 below-ground subway stations and trains throughout Boston.

"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," Tara O'Toole, Homeland Security Undersecretary, said in a recent statement.