The national environmental indicator for ambient air quality reports on the number of exceedances of the national environmental standards and peak levels and annual averages for PM10, carbon monoxide, nitrogen dioxide, sulphur dioxide and ozone. This report card reports on this indicator for carbon monoxide, nitrogen dioxide, sulphur dioxide and ozone.
The maximum levels of these four pollutants are reported against the national environmental standards and guidelines in areas where monitoring occurs. For some pollutants, supporting information is provided by reporting the maximum levels of these pollutants against relevant international guidelines (eg, WHO global air quality guidelines). This only occurs for pollutants where international guidelines differ to the national environmental standards or national guidelines. Information is also presented for annual averages as they take into account both peak and low pollution periods, giving an important long-term picture of air quality.
Results for selected monitoring sites are presented in figures throughout this report card. The selected sites are primarily urban, reflecting where people live and potential exposure to pollutants. The locations for the monitoring results presented are discussed in the key findings section for each pollutant. At least one site is presented for each region where regular monitoring occurs.
It is important to note that the weather has a strong influence on air quality and normal meteorological fluctuations that occur from year-to-year, can significantly affect monitoring results. For example, some weather conditions trap pollutants near ground level, having adverse effects on air quality. Conversely, particularly windy and unsettled weather can quickly disperse pollutants, having a beneficial effect on air quality.