8 Trends in Contaminant Concentrations in New Zealand
Figure 8.1 shows the median CO and NO2 concentrations measured at long-term air quality monitoring sites in Auckland and Christchurch. While no trends in NO2 concentrations are evident at either site, median CO concentrations at Queen Street, Auckland and Packe Street, Christchurch suggest a decrease in CO concentrations over the period 1992 to 2001. This decrease in CO concentrations is likely to represent reductions in motor vehicle CO emissions as well as possible improvements in emissions from domestic home heating in Christchurch.
Figure 8.1: Median CO and NO2 concentrations measured in Auckland and Christchurch from 1992 to 2001
See figure 8.1 at its full size (including
text description). A long-term record of one-hour average SO2 concentrations is also available for the St Albans monitoring site in Christchurch. No significant changes in the median SO2 concentration are evident in the St Albans SO2 data from 1992 to 2001. In Auckland, median SO2 concentrations are variable with higher values recorded during 1997-2000. Changes in ambient air concentrations of SO2 in most areas will depend on variations in industrial sources of SO2 or in the use of coal for domestic home heating. The latter could change with significant variations in coal type (e.g. changes in the sulphur content) or the extent of coal use.
Because only a limited amount of air quality monitoring has been carried out in New Zealand for O3, BaP and benzene it is not possible to determine trends in concentrations of these contaminants.
