In New Zealand, nitrogen dioxide (NO2) mostly comes from motor vehicles and can cause health issues including respiratory problems. The highest concentrations are usually found near busy roads in urban areas.
Monitoring in Richmond has been undertaken by NZ Transport Agency Waka Kotahi near the Richmond deviation, as part of the national air quality (NO2) monitoring network, but until recently there has been no urban monitoring in residential areas of Richmond or Motueka townships.
In 2021 the World Health Organization (WHO) substantially revised its guidelines, setting much lower values for many pollutants including NO2. The Health and Air Pollution in New Zealand(external link) 2022 (HAPINZ) report highlighted that nationally NO2 from traffic emissions has a much larger contribution to air pollution health impacts and associated social costs than previously thought.
For these reasons, the Council undertook a NO2 surveillance study in Richmond and Motueka during winter 2025. The objective of the study was to gather monthly urban background NO2 information to understand if there was an issue that required further investigation.
A network of NO2 diffusion tubes were set up in Richmond (14 sites) and Motueka (5 sites), monitoring between 23 June and 24 September 2025. Each monitoring location consisted of triplicate diffusion tubes set 2m-3m above ground level, and the tubes were replaced monthly. This low-cost surveillance method provides a very useful technique of evaluating spatial variations in longer term concentrations (e.g. monthly).
Monthly NO2 concentrations varied from 4.1 µg/m3 at Motueka Port to 21.5 µg/m3at McGlashen Ave near the junction with SH6 in Richmond.
As there are no monthly NO2 concentration standards or guidelines to compare the results to, the monthly results were compared to the WHO 24-hour mean guideline of 25 µg/m3. Four sites in Richmond and one site in Motueka had average monthly concentrations that exceeded 18 µg/m3. Given that at least 30% of days experienced higher wind speeds which would have substantially reduced NO2 concentrations on these days, it is likely that sites with peak monthly concentrations more than 18 µg/m3 could have occasional daily concentrations which could reach or exceed the WHO daily guideline.
Read the full report: Richmond Motueka NO2 Survey Final.pdf (pdf 2 MB)
The results suggest that there is a potential issue that we should investigate further, with the report recommending a short-term winter NO2 monitoring campaign at a representative site in Richmond and Motueka. This would enable direct comparison of NO2 concentrations with current National Environmental Standard for Air Quality (200 micrograms µg/m3 for 1-hour). Staff are seeking budget for this study through the 2027 Long Term Plan process.
We can all help to reduce NO2 emissions, as the main source of NO2 in urban areas is motor vehicles. So next time you plan your local journey – whether that’s to the shops, park, school or work – can you walk, bike, car share or take the bus instead of using your car? Small changes like this can make a difference when we collectively try. Walking or biking is both good for you and the environment, with health benefits from exercising and reducing air pollution.
More information on sustainable transport options can be found here:
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