The federal government Wednesday will begin releasing bacteria at Red Line MBTA stations in Cambridge and Somerville at set times to test sensors designed to detect biological agents that could be released in a terrorist attack.
The U.S. Department of Homeland Security and the Massachusetts Bay Transportation Authority said in a press release Monday that the harmless bacteria is non-infectious and the tests will be performed when the stations are closed.
The tests will begin Wednesday and will be held periodically over the next year at the Harvard and Porter Square stations in Cambridge and the Davis Square station in Somerville.
Signs will be posted in the MBTA stations one day before each scheduled test, according to the federal agency.
Biological detection sensors have been installed at the stations and the tests are
