BOSTON (CBS) – Homeland Security officials were scheduled to launch a first of its kind testing on the T at 1 am Wednesday morning. They’ll be releasing a bacteria in the air to test new sensors designed to detect a biological attack.

The Department of Homeland Security is working with the MBTA on the tests in three Red Line stations: Porter, Davis and Harvard Square.

Deputy Chief Lewis Best says they will use a dead Bacillus subtilis bacteria, that is safe. He says, “It is used in agriculture and is also a food supplement.” He says it will be dispersed as an aerosol spray.

Homeland Security officials say right now, it can take days to detect a biological attack, and the new sensors will be able to detect a problem in minutes. Deputy Chief Lewis explains, “Early detection is key. This will give us enough lead time to act very quickly, to allow us to properly adjust our emergency response to such an incident. These detectors could alert us in as short as 20 minutes, so the results that would be gleaned from this would be tremendous.”

They will be testing overnight with the bacteria 6-8 times a month for the next 6-8 months.