Particles are classified by their size with PM10 referring to inhalable particles smaller than 10 microns (μm) in diameter. Of the inhalable particles, those smaller than 2.5 microns (PM2.5) can penetrate more deeply into the respiratory system and therefore pose the greatest risk to health (see diagram of particle sizes).
Benchmarking & Resources has more information on the guidelines and standards used for the following summary tabs.
Annual PM10 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 days per year with at least 18 hours data present.
Graphs of daily average PM10 are shown with colour bands representing a percentage of the national standard of 50 μg/m3. High pollution days (exceedances above 50 μg/m3) are shown in the red colour band and days that met the regional target (33 μg/m3) are shown in the light blue colour band. Hover over the graphed days to see specific values. Note the high value for Lower Hutt in January 2023 was due to nearby demolition works.
Graphs of annual average PM10 show years above the World Health Organization guideline (15 μg/m3) in the red colour band and years that met the regional target (13 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. Results for years marked with * have been adjusted to account for a change in monitoring instrument.
This table shows the number of PM10 high pollution days per year (exceedances) above the national standard limit of 50 μg/m3. The standard allows one day per year to be above this limit. Blank lines are shown where there was no monitoring data.
Annual PM2.5 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 days per year with at least 18 hours data present.
Graphs of daily average PM2.5 show days above the regional target of 17 μg/m3 in the dark blue and red colour bands and days that met the World Health organization guideline of 15 μg/m3 in the light blue colour band.
Graphs of annual average PM2.5 show years above the regional target of 7 μg/m3 in the light blue and red colour bands and days that met the World Health Organization guideline of 5 μg/m3 in the light blue colour band. Only years with at least 75% data capture are shown.
This table shows the number of high PM2.5 pollution days per year, where daily averages were above the World Health Organization guideline of 15 μg/m3. The guideline allows three day per year to be above this limit. Blank lines are shown where there was no monitoring data.