Boston's subway system is the site of a test to evaluate whether new sensors effectively detect biological agents.
Scientists will spray small quantities of a nontoxic virus in subway tunnels after hours to test the sensors. Similar tests have been conducted since 2009 to help determine how gases travel through the system and to identify where to place sensors.
This stage of testing began Aug. 29 at Red Line stations Davis, Harvard and Porter. Tests will occur five to eight times a month for six to eight months. The test virus, Bacillus subtilis, doesn't cause disease and is nontoxic to humans, animals and plants, according to the Environmental Protection Agency.
The sensors could work in other areas, but there are currently no plans to test or deploy them elsewhere, a U.S. Department of Homeland Security official said.
There is currently no 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," he said, referencing the 1995 poison gas attack in Tokyo's subway. "We're guarded by the events of the world."
Megan Heffernan, a 22-year-old Boston University public health student, said she thinks the testing is a good idea.
"You don't want to have sensors that don't work," Heffernan said at South Station.
Chris Danforth, a 28-year-old bartender from Newton, said the possibility of a bioterror attack won't change his transportation habits.
"Talk of bio weapons has been around since World War II," he said in South Station. "Do I care so much? Not really."
This program aired on September 4, 2012. The audio for this program is not available.