Fire crews spent more than six hours dealing with a chemical spill in Llantwit Major.
Two fire crews and a specialist unit were called to West Street at just after 3.35pm on Thursday afternoon.
Local residents within 100 metres of West Street were told to keep their windows and doors closed.
The road was blocked for several hours between College Street and Castle Court although traffic in the area coped well.
The spill was removed by highway workers from Vale of Glamorgan Council.
A spokesperson for South Wales Fire and Rescue Service said: "Crews from Llantwit Major and Bridgend attended the incident, in addition to our chemical incident unit. Four breathing apparatus, gas monitor, environmental pack and small tools were used."
"The spill was covered using granules and salvage sheets were used to cover the spillage, which was sealed appropriately. The incident was handed over to the local authority, and the police remained on the scene to control the cordon."
"Local authority highways teams removed the substance following their relevant protocols and standard operating procedures, and SWFRS have recommended that the local authority liaise with their own specialist advisor for retrieval and disposal of substance."
Fire crews received the stop message at just after 9.45pm.

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