Firefighters were called after the ground floor of an office block in Union Street was covered in a white cloud, which workers thought to be smoke.
However, after inspecting the building, the Fire Service found that a broken air conditioning pipe was emitting a mixture of gas and oil creating a thick white cloud that was initially mistaken for smoke.
The roads around Union Street were closed for about an hour as firefighters got rid of the gas cloud and air conditioning engineers were called. They have since been reopened.
