Figure 12.1: Percentage of measured 24-hour average PM₁₀ concentrations within air quality categories in Otago

Text description of figure

There are four graphs showing 24-concentrations of PM₁₀ taken in Otago.

The first graph shows concentrations recorded in Mosgiel between 1998 and 2001, and Green Island between 2000 and 2001. Concentrations in Mosgiel varied considerably over the period. Over 30 per cent of measurements were over the guideline in 1998, whereas in 2000 less than 5 per cent of measurements were over the guideline. At Green Island concentrations were predominantly 'acceptable' or better, but 20-30 per cent of measurements were in the 'alert' category, or over the guideline.

The second graph shows concentrations recorded in South Dunedin in 1998 and 2001, and Dunedin North between 1997 and 2001.

In South Dunedin concentrations were relatively poor, with 35-55 per cent of concentrations in the 'alert' category, or above the guideline. Concentrations deteriorated slightly between the two dates. In Dunedin North concentrations were predominantly 'good' or 'acceptable' throughout the period, with the proportions of 'alert' concentrations, and concentrations over the guideline decreasing over the period.

The third graph shows concentrations measured in Milton, Arrowtown, Balclutha, Queenstown, East Taieri, Cromwell, between 1997 and 1999.

In Milton nearly 10 per cent of measurements were over the guideline, and 20 per cent of measurements were in the 'alert' category. In Arrowtown nearly 10 per cent of measurements were over the guideline, and 20 per cent of measurements were in the 'alert' category. In Balclutha five per cent of concentrations were over the guideline, and about 15 per cent were in the 'alert' category. In Queenstown most measurements were in the 'acceptable' category, with just over 5 per cent in the 'alert' category. In East Taieri over 90 per cent of concentrations were 'good'. In Cromwell over 30 per cent of concentrations were over the guideline, and another 15 per cent were in the 'alert' category. In Oamaru about 40 per cent of concentrations were in the 'good' category, 40 per cent in the 'acceptable' category, 15 per cent in the 'alert' category, and 5 per cent of concentrations were over the guideline.

The final graph shows concentrations of PM₁₀ in Alexandra between 1997 and 200. At the beginning of the period nearly 50 per cent of measurements were over the guideline. Readings improved by 1999 with only 20 per cent over the guideline, but deteriorated slightly for the rest of the period.