Traffic-related air pollution is measured at three core sites and is supplemented by a regional network of low cost nitrogen dioxide (NO2) passive diffusion tubes. (A picture of NO2 tube site can be seen here). Air pollution levels from traffic vary considerably across the region and so a larger monitoring network is needed to capture representative regional and local trends. Some sites are also part of the Waka Kotahi national monitoring network. The passive tubes are a manual monitoring method and data is only available as monthly averages after the tube has been analysed in a laboratory.
Benchmarking & Resources has more information on the guidelines and standards used for the following summary tabs.
Annual NO2 summary results are shown in the map and table. Annual averages are only reported for sites with more than 75% data capture.
Map usage: drag and scroll on the map to move and zoom in on areas of interest, hover on the site circles to see more information, and use the selection box ( ) to subset the map and table data to that area.
Table usage: click on sites in the table to highlight them on the map, and click on table headers or the arrows next to them () to sort the data by that column – holding the shift key allows sorting over multiple columns.
All values in μg/m3. Data capture (%) refers to the proportion of total hours with at least 45 minutes of data present and the proportion of total days with at least 18 hours of data present.
Graphs of daily average NO2 show days above the World Organization guideline of 25 μg/m3 in the dark blue colour band. There were no days above the regional target of 66 μg/m3 in the red colour band.
Hover over the graphed days for specific values.
Graphs of annual average NO2 show years that met the World Health Organization guideline of 10 μg/m3 in the light blue colour band.
Note only previous years with at least 75% data capture (ie, 274 days with data present) are shown.
The map shows annual average NO2 (μg/m3) from the passive tube monitoring sites across the region used to track long term trends in traffic-related air pollution.
The table shows seasonal averages based on NZTA reporting criteria for summer (January to March) and winter (July to September). NO2 levels are generally higher in winter than in summer most as the colder temperatures and lower wind speeds during winter are less favourable for dispersing vehicle emissions.
Map usage: drag and scroll on the map to move and zoom in on areas of interest, hover on the site circles to see more information, and use the selection box ( ) to subset the map and table data to that area.
Table usage: click on sites in the table to highlight them on the map, and click on table headers or the arrows next to them () to sort the data by that column – holding the shift key allows sorting over multiple columns.
All values in μg/m3. Data capture (%) refers to the proportion of total months with data present per year. Toggle between tabs to see summaries at NZTA ID (site) level or aggregated by site type. See benchmarking & resources for more information on each site type.