Auckland Council has published a report on long-term trends in Auckland’s air quality for the years 2006 – 2018.
The good news is that in most locations, both short-term and long-term PM10 and PM2.5 concentrations have decreased (Figure 1).
Similarly, nitrogen dioxide (NO2) shows marked decreases in concentration over the long-term. However, short-term trends in NO2 are starting to show increases in concentration at several sites near major roads.
Full report here.
Figure 1 Theil-sen deseasonalised trends for PM10 at Takapuna (2006-2018)