Up to yesterday, Cromwell, Arrowtown and Milton had all exceeded the National Environmental Standard of 50mcg of particulates per cum of air 30 times already this year.
Cromwell exceeded this limit 33 times throughout the whole of last year, 24 times in 2015 and 48 times in 2014. Arrowtown exceeded it 32 times last year, 29 times in 2015 and 47 times in 2014. Milton exceeded it 37 times last year, 30 times in 2015 and 14 times in 2014. One day last month, Milton tripled the standard with an average of more than 150mcg.
Alexandra’s readings show only two breaches this winter.
Otago Regional Council environmental scientist Deborah Mills said Alexandra’s low readings were due to moving an instrument 750m into the town, to the Alexandra Primary School, after the land it was previously on was sold. A temporary instrument placed at the original site showed readings similar to those in the other towns, she said.
Much of the pollution comes from residential heating using old wood burners.
Results of a regional council survey of 400 Central Otago residents last month found 62% of households still used wood or multifuel burners.
Dr Mills said there was "significant" evidence elevated particulate levels adversely affected the health of individuals, particularly the very young, the elderly, and those with cardio-respiratory conditions.
"Some of these effects include reduced lung function, inflammation of the lung, coughing and wheezing, chronic bronchitis, and other respiratory diseases. Quantifying those events is very difficult, particularly in small population centres."
While the regional council says air quality has improved in the past 10 years, it wants to combat the problem further by developing its new air quality strategy. The draft version will be presented to councillors later in the year.
