Road workers who smelled gas alerted firefighters to a leak coming from a Saint Hill St flat on Thursday afternoon.
"There was quite a heavy gas leak coming from one of the properties down there and it was picked up by road workers outside," Fire and Emergency senior station officer Craig Gardiner said.
Fire and Emergency was called to the property about 1.20pm.
"Between the gas department and the fire service we used breathing apparatus to go in and measure the gas levels."
Gardiner said it was determined it was not explosive but was "very strong".
The property was ventilated with fans and measured with gas ventilation equipment.
It was determined the gas was coming from a heater which was on but not lit.
Gardiner said it was important for people to ensure gas appliances were safe and working and, if not, to get them checked out.
At the same time firefighters were called to a commercial property on the corner of Maria Place and Victoria Ave for a small microwave fire "where the food had caught fire in the microwave".
The fire was contained within the microwave.