Booragul resident Hans Siegers outside his home.
MYSTERY surrounding a midnight stench that wafts through Booragul has residents calling for answers.
Park Parade resident Hans Siegers says an unpleasant, sulphur-like industrial substance can only be smelt late at night when north to north-west winds are present.
The smell has become a talking point for the street, with residents often waking up in the middle of the night to close their windows to block the odour.
Mr Siegers approached one of the west ward councillors to investigate the smell, who dismissed Mr Siegers claims as "someone lighting matches" or "a hangover from Pasminco".
Air pollution levels have become a contentious issue for Lake Macquarie City Council this year, after it was revealed in February that the city had recorded the state's highest levels of nitrogen oxides - a major airborne pollutant from coal-fired power stations.
Lake Macquarie also had the state's second highest sulphur dioxide emissions.
Councillors have called for a public air monitoring station to be installed in Lake Macquarie as recently as last month.
They also voted to make a submission on behalf of Lake Macquarie residents to a Senate inquiry into the impacts on health of air quality in Australia.
A Lake Macquarie City Council spokesperson said that the council was aware of eight industrial sites in the city with environment protection licences that include air quality monitoring requirements.
These stations monitor total particulates, particulate matter less than 10 microns in size, oxides of nitrogen, oxides of sulphur and carbon monoxide.
The council said data from the stations was publicly available on the Environmental Protection Authority website.
The council said it had not received any complaints from residents regarding smells in the Booragul area, but had received complaints about odours in the Cardiff and Glendale areas, as well as one complaint about odour coming from the water at Morisset in January.
The council said investigations were still continuing into those three complaints.