A smoke-like odor emitting from a few MBTA Red Line stations Friday morning prompted a response from the Cambridge Fire Department.
Fire officials said crews investigated the odor of smoke and haze at Harvard, Central and Kendall MBTA stations. After investigating and taking air samples, Cambridge firefighters determined the air was normal.
The odor has since dissipated and fans were used at the station for ventilation, according to fire authorities.
A train with a mechanical issue was placed out of service and taken to the Alewife yard. It is unclear if the train and odor were connected.
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Service has not been affected by the response, Cambridge Fire said.
The response comes a week after an MBTA Red Line train derailed near the JFK/UMass station in Dorchester. The derailment caused delays of more than an hour the day of the incident and snarled traffic nearby. Brief delays continued the days following the derailment as crews worked on the damage.