Boston subways begins biological agent detector tests

In Boston, new sensors are being tested in the subway system to see if they're able to effectively detect biological agents.

Small quantities of a nontoxic virus will be sprayed in tunnels after hours to test the sensors. Similar tests have been done in the past to show how gases travel in the tunnels in order to find where best to place the sensors, reports.

The tests will occur five to eight times a month for six to eight months and began in August at the Davis, Harvard and Porter Red Line stations. The test virus, Bacillus subtilis, is non-toxic to humans, animals and plants, according to the Environmental Protection Agency.

The tests are not a reaction to a specific bioterror threat to Boston's transit system, Massachusetts Bay Transportation Authority Deputy Chief Lew Best said.

"We know that history tells us transit systems have been attacked by terrorist organizations," Best said, referencing the 1995 poison gas attack in Tokyo's subway, reports. "We're guarded by the events of the world."

Megan Heffernan, a 22-year-old Boston University public health student, supports the idea of testing.

"You don't want to have sensors that don't work," Heffernan said at South Station, according to