Reports & publications- Air Quality
West Coast Air Quality report April 2026
Poor air quality is a winter problem on the West Coast, caused mainly by burning of solid fuel for domestic home heating. Fine airborne particulate matter (PM) is the main contaminant of concern. This report draws together air quality monitoring undertaken by the West Coast Regional Council over more than three decades: the long continuous record for the Reefton airshed, and the investigative monitoring carried out at Westport, Greymouth and Hokitika as part of the wider West Coast monitoring programme from 2022 to 2025.
It reviews that work alongside historic monitoring of 1994 to 2003, sets out what is now known about the state of air quality in each town, and makes recommendations for future monitoring.
2024 Greymouth and Westport Review
This report compares PM2.5 monitoring data to National Environmental Standards and the WHO (2021) guidelines and evaluates the reliability of the monitoring site in light of 2023 spatial monitoring. Data is considered in conjunction with meteorology to evaluate future monitoring needs for Westport.
It also assesses emissions from key sources of particles in Greymouth and evaluates these to identify hot spots where concentrations might be highest. Data is considered in conjunction with existing spatial monitoring data carried out in 2023 and meteorology to identify priority areas for the establishment of a long-term monitoring site for PM2.5 in Greymouth should further monitoring be necessary.
2024 PM Source ID GNS Westport
This report presents results of an analysis of particulate matter concentrations and composition from a winter PM2.5 and PM10 sampling campaign at Westport. Particulate matter samples were collected from May-September 2023 as part of a PM2.5 and PM10 airborne particle sampling programme at Westport.
The sample set formed the basis of a study of particulate matter composition and the attribution of sources contributing to particulate matter concentrations. The particulate matter elemental composition data showed black carbon, a product from combustion sources, was a dominant contributor to PM2.5 concentrations. For PM10, black carbon, sodium and chlorine were also important components which indicate the primary influence of the PM2.5 combustion sources along with coarse particle marine aerosol (sea salt) sources.
