Figure A1.5: Hourly NOx vs. NO₂ for all Auckland stations, 2004

Text description of figure

This figure plots hourly ambient concentrations of oxides of nitrogen (NOx) on the x-axis against hourly ambient concentrations of nitrogen dioxide (NO2) on the y-axis for eight monitoring stations in Auckland (Khyber Pass, Queen Street, Takapuna, Henderson, Penrose, Kowhai, Mt Eden, Musick Point). The plot shows a direct correlation with low NOx levels equating to low NO2 levels and vice versa. The point at which the NO2 concentration tends to achieve its conservative maximum is when the NOx is around 1,000 µg/m3 or greater, which gives rise to a maximum one-hour NO2 concentration of 200 µg/m3 – the one-hour national ambient air quality standard.