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Nitrogen dioxide levels in air

Photograph of vehicle emission testing.


Why we monitor nitrogen dioxide levels in air

Nitrogen dioxide (NO2) is a gas that affects lung function. It usually forms from the oxidation of nitrogen oxide (NO) in the atmosphere. The main sources of nitrogen oxide are the burning of fossil fuels (for example, coal, gas and oil) and motor vehicle emissions. In urban areas the main source of nitrogen dioxide is motor vehicle emissions. Waikato Regional Council aims to measure nitrogen dioxide levels in Hamilton at a busy traffic site about once every 3 years.

Nitrogen dioxide affects people’s lungs by aggravating asthma and by decreasing their ability to fight infection - for example, bacterial lung infections. People most sensitive to nitrogen dioxide include young children, children and adults with asthma and adults with respiratory problems.

Highest concentrations of nitrogen dioxide are likely to occur in or near urban areas.
The Waikato Regional Plan sets guideline concentrations for nitrogen dioxide at 200 µg/m3 for a one hour average and 100 µg/m3 for a 24 hour average.

What's happening?

No samples were within the ‘alert’ or ‘action’ categories for Peachgrove Road or Ohaupo Road but some samples were within the ‘alert’ or ‘action’ categories for the corner of Avalon Drive and Te Rapa Road during 2011. Data for the 24 hour average are presented relative to the national guideline of 100 µg/m3.

In 2005 the Government set national environmental standards (NES) for air quality, including a standard for NO2 of 200 µg/m3 for a one hour average. It allows nine hours per year when concentrations can be greater than 200 µg/m3.

Concentrations of NO2 were measured in Hamilton at the corner of Avalon Drive and Te Rapa Road from March 2011 to March 2012, including a three month period when roadworks increased congestion and truck movements in the area.  A total of 52 exceedences of 200 µg m-3 (hourly average) were measured.  No exceedences were measured following the completion of the road works in July 2011. No exceedanceds of the 200 µg/m3 (one hour average) standard for NO2 have been measured during 2013 at Ohaupo Road.

>>Find out more about these data and trends


More information

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When this indicator is updated

This indicator will be updated in 2019.

Contact at Waikato Regional Council

Air Quality Scientist - Science and Strategy Directorate

Last updated 9 May 2014