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National air quality (NO2) monitoring network

Published: | Category: Nationwide statistics , Statistics & surveys | Audience: Local & regional government

The state highway system accounts for about 12% of New Zealand’s roads and around half of the 40 billion vehicle kilometres New Zealanders travel each year. Motor vehicles travelling on roads emit an array of air pollutants which can contribute to harmful effects on human health and smog formation.

The Transport Agency is committed to being socially and environmentally responsible and has specific objectives in its state highway environmental plan for improving air quality, including:

  1. Understand the contribution of vehicle traffic to air quality.

  2. Ensure new state highway projects do not directly cause national environmental standards for ambient air quality to be exceeded.

  3. Contribute to reducing emissions where the state highway network is a significant source of exceedances of national ambient air quality standards.

In 2007, the Transport Agency began a national monitoring programme to determine relative levels of vehicle pollution across the state highway network. Passive samplers are now located at more than 120 sites across New Zealand to measure nitrogen dioxide (NO2) as a proxy for vehicle-related air pollution. The overall aim is to see a decreasing trend in NO2 concentrations measured at these sites. This aligns with the government’s desired long-term impact which seeks a ‘reduction in adverse environmental (air quality) effects from land transport’ as stated in the Government Policy Statement for Land Transport.(external link)

The annual report summarises the data measured at the national network sites since 2007. It is complemented by a metadata report, which provides details for each site in the network, and an operating manual which outlines how the network is operated.

The following annual reports are available on request from It should be noted that data contained withing these reports, for the 2013 year, has been found to include errors (affecting 2013 annual and seasonal averages). 

Ambient air quality monitoring network 

  • 2007-2014 annual report
  • 2007-2015 annual report
  • 2007-2016 annual report

Publication details

  • Author:
  • Published: October 2016
  • ISBN/ISSN: ISBN 978-0-9941397-7-1
  • Contact:
  • Also known as: NO2 Monitoring Report