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Mosgiel's air quality improved slightly during winter but not enough for the town to rest on its laurels, Otago Regional Council air quality scientist Deborah Mills says.
The town has until 2016 to meet the national PM10 (very small particle) standard of having no more than three 24-hour readings exceeding 50mcg per year.
''It is possible. They're not too far off.''
Air-quality readings were taken by a continuous monitor in the Factory Rd industrial estate.
This winter five readings exceeded that standard, which was fewer than the town's average since recording began in 2006 of seven per year, she said.
Most of the top readings occurred in June and one in July.
Mosgiel is in air zone two, which encompasses Otago towns with less of a problem with air quality and averages below 10 exceedances per year.
When the top 10 highest air pollution days in Mosgiel in winter were averaged out, the reading came to 51mcg.
''It's not way over and is 15% lower than the long-term average.''
However, it was a mild winter and, as the town did not have the ''stark'' problems of other areas such as Alexandra, it was hard to tell how much of the drop was weather-related and how much was a cut in emissions, she said.
''It's a slight improvement, but we don't know if it is a real trend or not.''
There was still a problem with people burning rubbish and garden waste outside on the Taieri Plain.
''That contributes on occasion to some of the numbers, so we will have to look at that issue in coming years.''
Under air zone two regulations, natural attrition was being used to help improve air quality. That meant if homeowners were replacing a heating source they had to install a burner that was compliant with national standard emission levels.
Until then homeowners could continue to use their existing burners and fuel it with coal but were encouraged to use their burners efficiently.