Debris from the ceiling was found on the Forest Hills commuter rail platform, causing concern for public safety.
The material, known as bridge joint felt, is used as padding near the joints of the ceiling and weighs less than a pound.
According to a spokesperson for the T, water was coming through the joint where the debris was found.
This incident follows a more serious one on March 1 when a 25-pound ceiling panel fell on the ground at the Harvard Red Line station.
The T removed all the ceiling panels on the southbound side of the station after the incident.
Although the platform in Jamaica Plain where the debris was found is open, there is still a significant amount of water coming down.
Public officials are urging the T to address these safety concerns immediately.