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Variations in quality of air throughout city

A new site could be needed for the equipment that monitors air quality in Gisborne city, the district council’s environmental planning and regulations committee was told.

The council is due to replace its current air quality regulatory monitor this financial year.

A just-completed study shows that air quality is variable thoughout the city, the committee was told.

A report from environmental risk team leader Kate Sykes said the council had gathered air quality data from the early 1990s of particulate matter from three monitoring sites established over the years.

These showed localised variations in levels of PM10 level particles but all were well within the national environmental standards for air quality.

Because of this, Tairawhiti was not required to have a gazetted airshed as defined in the standards.

Despite this, smog had been observed in residential suburbs, particularly in winter.

Smog was largely attributable to PM10 and PM 2.5 level particulates emitted from solid fuel domestic heating appliances.

Several sites in Whataupoko and between outer and inner Kaiti recorded several nights with PM10 values over the national standard of 50ug/m3 (micrograms per cubic metre of air) while on the same night the regulatory monitor at Gisborne Boys’ High School recorded no exceedances.

This discrepancy suggested the location of the reguatory monitoring site did not correspond to the highest PM10 concentrations and that there may be locations in Gisborne that require further investigation for future national standard compliance.

PM 10 levels in the city were also influenced by sea salt, dust from Poverty Bay cropping activities and sediment carried by vehicles on road networks.

Emissions from motor vehicles were a major source of nitrogen dioxide and could be a localised problem around congested or high traffic roads.

It was well documented that breathing particulate matter was harmful to human health.

Since data collection began there had been a significant increase in vehicle numbers, particularly diesel-powered ones on the roads, as well as infill housing and new housing developments, the report said.

Acting science manager Peter Hancock showed an animation that confirmed that air quality could be quite variable.

When it was really cold and still, smoke from fires hung around and that was when the worst conditions were seen, he said.

Malcolm Maclean said more information was needed on treated wood and its effect.

Environmental services and protection director Nick Zaman said treated timber was a real no-no because of the arsenic in it. Salted wood was not good for a wood burner.

People should have well-seasoned dry wood ready to use.