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Published: 2002-06-07 00:00:00

Air quality in the Waikato is sometimes worse than national guidelines, especially in winter.

New national air quality guidelines just released have reduced the guideline level for fine particulate matter (PM10) by more than half – from 120 to 50.

A report to this week’s Environment Waikato Environment Committee meeting says more monitoring is needed to find out the cause and what may need to be done in areas where poor air is now identified.

Air quality in the Region was generally perceived to be excellent, however some parts had poor air quality at times, the report said. This could lead to effects from odours, poor visibility, soiling and corrosion of buildings to effects on health. Health effects from fine particulates ranged from eye and throat irritation, increased bronchitis and asthma symptoms to respiratory illness and death.

Home heating was a major source of particulate emissions in urban areas and was likely to be the main source in Hamilton, Te Kuiti, Taupo and Tokoroa.

Of the monitored areas, Tokoroa had the worst fine particulate levels in both magnitude and frequency of high pollution events, most likely from home heating. The new guidelines were exceeded on about seven percent of the days monitored in 1999 and 2001, with another 16 percent last year in the alert category.

Concentrations would have to be reduced by about 33 percent to meet the air quality target, and more investigations were needed to confirm the sources of the high readings.

In Hamilton, concentrations exceeded guidelines twice last year. Domestic heating contributed more than 80 percent of particulate emissions.

However the city had low concentrations of carbon monoxide and nitrogen dioxide, and lead monitoring showed a significant decrease since the 1980s when lead was removed from petrol. In Taupo, particulate concentrations were seen to have exceeded the guideline once, although with limited monitoring it was likely to have happened more often.

It was recommended that monitoring be continued in Hamilton, Tokoroa, Te Kuiti and Taupo as intervention may be needed, especially in Tokoroa. Other small towns could also be monitored, such as Huntly, Matamata and Te Aroha.

The report also recommended monitoring nitrogen dioxide in Hamilton one year every three years and assessing ozone concentrations in the north of the Region during summer to establish any effects migrating from Auckland.

Results will be included on Environment Waikato’s website and sent to the Ministry for the Environment to be included in the national indicators programme.

Cr Steve Osborne said that it was important to use dry wood for home heating and to have small, hot fires so that less smoke was produced on cold nights.