Pollution: How does your town compare?

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Stafford Street, the main street of Timaru, South Canterbury. Photo / Mark Mitchell

By Gemma Hartley

New Zealand scientists are trialling new technology in Canterbury that could revolutionise how centres can better monitor and control air pollution.

A new stage of a Niwa air quality project is about to get underway in Rangiora, as a World Health Organisation (WHO) index again highlights how some South Island towns have rated poorly for air pollution.

Last year, scientists installed and tested new hi-tech sensors in 14 Rangiora homes during September to detect when people were using their woodburners.

Each participant had since received an information pack with detailed information about the air quality in their home, temperature variations and dust peaks.

The scientists found that while it was easy to detect when a woodburner was lit, it was much harder to tell when the fire had stopped burning.

There were also big differences between homes, with some people lighting and boosting fires a lot and others lighting only once a day.

Niwa air quality scientist Dr Ian Longley said the new sensor technology trialled last year had the potential to provide new and valuable information.

"This year we are planning to do some follow up testing with our existing participants as well as recruit more people in Rangiora to help us out," he said.

"What we learn this year will then enable us to progress to a much larger study, perhaps in other towns, in 2017."

Niwa has also developed the indoor state-of-the-art monitoring technology contained in small and low cost units, which contain sensors for particles (dust, smoke or soot) and carbon dioxide and can detect sudden increases in the levels of particles in the air.

The indoor data was combined with data from temporary weather stations set up around Rangiora, and from six of Niwa's experimental outdoor air quality sensors placed around the town to determine whether different parts of the town had different air quality and how that varies from day to day and place to place.

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Dr Longley said the units could make a huge difference to our understanding of what causes air quality problems.

"We suspect this could be a game changer in being able to identify problems and their causes and enable communities to work more constructively with councils on devising solutions."

Meanwhile, WHO has released an updated index that measures air pollution in hundreds of cities around the world.

New Zealand's figures, from 2012, remain largely unchanged from previously-released WHO indexes, but show Timaru as having the highest level of PM10 -- tiny particulate matter small enough to be inhaled into the deepest part of the lung -- at 28.

On average in New Zealand, PM10 levels were 11.7 micrograms per cu m, much lower than the OECD average of 20.9 micrograms per cu m and much lower than the annual guideline limit of 20 micrograms per cu m set by the World Health Organisation.

Other centres meeting or exceeding that level, according to 2012 figures, included Invercargill (24) Gore (23) Alexandra (22) Ashburton (21) Christchurch (21) Geraldine (20) and Richmond (20).

Christchurch was the worst of New Zealand's major cities, while Wellington (13) and Auckland's air (14) was found to be much cleaner.

Despite the levels, a review by Parliamentary Commissioner for the Environment Dr Jan Wright last year concluded that the state of New Zealand's air quality was generally good, as could be expected in a windswept maritime country with a small population and little heavy industry.

While air quality was poorer in some towns and cities during cold calm days in winter, even in these places air quality is high on most days, she found.

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