High air pollution days in some Central Otago towns are happening up to 51 times more than the national standard for air quality, with less than two years until the regulations tighten again.
The winter air quality results for 2014 show Dunedin and Palmerston are the only towns in Otago meeting national standards for air quality, while Alexandra and Arrowtown continue to record the highest levels of air pollution in the region.
The two towns exceeded the national environmental standard of only one day a year recording more than 50mcg per cu m, 51 and 48 times respectively, an Otago Regional Council report said.
Councils have until September 2020 to meet that target but an interim target comes into force in 2016 of no more than three days over the threshold.
Air quality scientist Deborah Mills said the maximum level of PM10 (very small particles) recorded in Alexandra (106mcg per cu m) was 28% lower than the long-term average.
''But, looking at the average of the 10 highest days indicates there was no decline from last year.''
Arrowtown recorded the highest level of PM10 of the winter at 148mcg per cu m and the second-highest at 133mcg per cu m, but as its recorder had been moved it was not comparable with this year's data.
Clyde recorded twice as many exceedences as last year - 20 compared with 10 - but the reason for the variability at the site was not known, she said.
Cromwell recorded the third highest number of days over the threshold with 47, including two days over 100mcg per cu m, although one was caused, in part, by a burn-off outside town.
On the east coast, Milton had an unusual season, with only 14 high pollution days compared with its normal total of 38 days, probably due to a different weather pattern and the fact one or two major industries shut down over the period, Ms Mills said.
Balclutha's results were similar to last year, but despite having greater PM10 emissions than Alexandra and the relatively high coal use in the town, only recorded four high pollution days.
''This indicates the influence of climate in PM10 concentrations.''
The regional council acknowledged earlier this year it was unlikely towns in Central Otago would be able to meet the 2020 deadline. A review of the council's approach to air quality is due to be presented to council this month.
