Big improvement in air quality

Winter air quality has been ‘‘significantly better'' in Central Otago than last year, but it is still too soon to say why, according to the Otago Regional Council (ORC).

Fewer exceedances of national air standards had been recorded this winter, but that could be because of weather patterns rather than a switch to clean-heating appliances, ORC air-quality scientist Deborah Mills said.

Unsettled weather with winds that helped shift smog had meant there was not the same still air this winter that was usually found in Central Otago, Ms Mills said.

‘‘It's my intuition that the weather has played a big part [in improving air quality].

That's what we're guessing.''

A ‘‘winter round-up'' analysing data from daily readings of air quality in Central Otago would be completed in the next six to eight weeks and made public through the ORC, Ms Mills said.

Daily readings are taken all year in Alexandra, Clyde, Cromwell and Arrowtown, and readings are taken in Lawrence every third day.

A ‘‘statement of the environment of air quality'' was also being prepared by the ORC, which would show trends and regional differences going back to 2005, when detailed readings started to be taken.

The report would be released at the end of the year to the ORC and district councils, Ms Mills said.

‘‘It [will be] an interim look at where are we now, as we move towards 2013 when new national standards really kick in.''

Ms Mills said every conversion to a clean-heating appliance would ‘‘make an improvement'' in air quality, but it was ‘‘too early to tell'' if that would show in air-quality data.

She said many councils were struggling to meet strict new national standards and would not comment on whether they were realistic, but Central Otago District Mayor Malcolm Macpherson said, ‘‘I think we're learning that they're probably not''.

‘‘What's important is that we're moving in the right direction.

As long as people are making responsible decisions, that's good progress.''

He said there was an impression this winter had been cleaner and less polluted than last winter, but it was difficult to say if ‘‘a particular set of circumstances has led to a particular outcome.

It might be a decade before we can say whether we're on the right track''.

- Pam Jones