Monitoring and Research
Air pollution trends
Annual average trends are a good indicator of whether air quality is improving over the longer term. Now that monitoring has been carried out for many years in Auckland, we can see how concentrations have changed over time.
The following graphs show annual averages for five key pollutants in the Auckland region. Guideline values displayed are for shorter time periods and are discussed in the air pollutants section.
Fine particles (PM10)
The graph below shows how PM10 have changed over the last few years. Concentrations of PM10 have exceeded both the National Environmental Standards (NES) and Ambient Air Quality Guidelines (AAQG) at urban monitoring sites measured around Auckland.
Nitrogen dioxide (NO2)
NO2 concentrations in Auckland have increased over the past decade due to an increase in motor vehicles on the roads. NO2 concentrations are generally less than 66% of the NES at urban monitoring sites in the region but exceed the standards at roadside monitoring sites.
Carbon monoxide (CO)
CO levels have dropped significantly over recent years, but may still exceed ambient air quality guidelines. Maximum CO concentrations are generally less than the NES at urban monitoring sites in the region.
Ozone (O3)
Maximum ozone concentrations are close to the NES at ambient air quality monitoring sites within the region.
Sulphur dioxide (SO2)
SO2 levels decreased in the 70s and 80s due to reduction in coal use in industrial sites. It started to increase again with the influx of used diesel vehicles and decreased with improved fuel standards. However, concentrations are rising again with the increase in diesel vehicle numbers. Concentrations of SO2 measured at monitoring sites across the region are typically less than the NES1.
1 Recent changes to the World Health Organisation ambient air quality guidelines mean that some New Zealand guidelines and standards are now out of date.
For more information view our Airfacts 4: State of the Region's Air Quality
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