Westport spatial study of PM2.5 and continuous PM10 winter 2023
In winter 2023 we undertook a survey of the spatial distribution of PM 2.5 in Westport, following on from an initial survey in winter 2022 . PM 2.5 are fine particles in the air less than 2.5 microns which can be harmful to human health. The results of the 2022 survey showed areas of elevated PM 2.5 around Westport that may exceed standards. Repeating the survey over another winter established a better understanding of air quality in Westport and will help determine whether further work is required.
These spatial surveys are NOT for evaluating the performance of individual households and discharges. But they help us identify areas where air quality is poorest and may require further monitoring.
In winter 2023 we added three extra monitoring locations to the spatial survey to help provide more robust data for modelling (a total of 18 sites around the town). We also set up a temporary continuous monitor in Westport measuring PM 10 and PM 2.5. Alongside this we ran two reference samplers collecting particulate on filters which are lab analysed. The reference machines allow us to check data collected by other instruments to provide the most accurate results.
The current air quality standard in New Zealand is a PM 10 daily average limit of 50 micrograms/m3. The National Environmental Standard for Air Quality (NESAQ) is currently under review and it is proposed to change the national standard to a PM 2.5 daily average. Collecting both PM 10 and PM 2.5 data enables us to compare Westport air quality results to both the current and possible future standards.
Overall Westport PM appears reasonable. Monitoring is continuing at one location in the town at present. An evaluation of particulate collected on filters showed a significant part of the coarse fraction to be from biomass burning with contributions from natural sources such as sea salt and soil also.
Westport spatial PM survey winter 2022
PM sources and contribution Westport
Westport and Greymouth winter 2023 PM survey evaluation
Westport and Reefton SO2 and NO2 winter 2022
Sulphur dioxide (SO2) and nitrogen dioxide (NO2) surveys in Westport and Reefton were undertaken during winter 2022
NO2 and SO2 are products of combustion – such as solid-fuel burning for domestic fires and industrial processes or from vehicle emissions and they can have effects on human health, such as respiratory illnesses.
Some SO2 data was collected in Westport and Reefton in the early 2000’s. NO2 had not been monitored previously on the West Coast.
The NO2 / SO2 survey ran over two months during winter 2022. Passive sample collection tubes such as those shown below were installed at 16 locations around Westport and 15 locations around Reefton.
Results of this monitoring showed that levels of NO2 and SO2 were well below any guideline levels.
