Council undertook a targeted monitoring programme between 2019 - 2023 to better understand if there are air quality issues in the Motueka, Riwaka and Brooklyn areas.
This programme spanned several years and involved temporary monitoring of PM10 and/or PM2.5 over late autumn and winter. This was to understand if there are air quality issues associated with home heating and/or outdoor rural burning in the wider area, which may require permanent monitoring and a need to introduce management tools. The results of these studies are summarised below.
The National Environmental Standards for Air Quality (Air Quality NES) only requires the identification and monitoring of airsheds where air quality standards are likely to be breached. Council has undertaken winter-time monitoring in Motueka in 2006, 2014, and consecutively between 2018 and 2023 (inclusive) for PM10 and/or PM2.5. This monitoring has included a full year of PM2.5 data in 2022. The results have shown that PM10 is not likely to be breached which is the current Air Quality NES standard.
On this basis, the Council has concluded this temporary monitoring work programme of PM in Motueka until such time that a new standard for PM2.5 is introduced. In the meantime, Council’s focus will be on non-regulatory programmes such as education and best practice advice to support the community to reduce smoke pollution.
For more information on this monitoring programme, please contact Anna MacKenzie (Resource Scientist - Contaminants) or Diana Worthy (Team Leader - Natural Resources Policy).
The NES-AQ has been under review for several years. There is a standard for PM10 (particulate matter), but there are currently no standards or guidelines in New Zealand for PM2.5. More recent international investigations suggest that greater focus should be placed on the management of smaller particles, PM2.5, as these are typically more harmful and are more controllable, given their greater apportionment to anthropogenic sources relative to PM10. For this reason, Council’s surveillance air quality monitoring programme is focusing on PM2.5, in anticipation of future legislative requirements to monitor and manage PM2.5. In the interim, Council is using the World Health Organisation’s PM2.5 guidelines as a comparison.
Council completed temporary winter monitoring of PM2.5 at Ledger Goodman Park, Motueka, to continue building our baseline of air quality monitoring data. The monitoring instruments included a Partisol gravimetric air quality sampler (Thermoscientific 2025i) which is a reference monitoring instrument co-located with a dustmote sensor (ES-642).
The PM2.5 exceeded the 2021 WHO daily guideline value of 15 µg/m3 a total of at least 22 days (based on the dustmote sensor). The 2023 winter maximum PM2.5 concentration for Motueka was 21.8 µg/m3 on 10 August. Council’s Partisol instrument had similar results, with a total of at least 15 days exceeding the guideline (using a 1 in 3 day sampling regime).
This study ran concurrently with an air quality study in Murchison.
Read the full report: Murchison and Motueka PM (pdf 989 KB)2.5 monitoring network – May to September 2023
Council also commissioned an emissions inventory and a source apportionment study to better understand the sources of air pollution in Motueka, which will be used to help inform future management tools (if these may be required).
Read the reports:
Motueka
Council undertook a PM 2.5monitoring programme at Ledger Goodman Park, Motueka, to gather 1 year of continuous data using a reference gravimetric monitoring instrument (Partisol 2025) (from 1 January 2022 – 31 December 2022). There were six periods of no data captured due to various mechanical issues and a potential noise complaint. It is noted that three of these gaps were during the winter months, so there was an incomplete dataset over the 2022 winter period.
The PM2.5 exceeded the 2021 WHO daily guideline value of 15 µg/m3 a total of at least 21 days. Given the significant period of missing data over winter, additional PM2.5 exceedances were likely to have occurred. The data for 2022 shows the typical seasonal pattern, with peak PM concentrations occurring in winter which is associated with the use of wood for home heating. The 2022 winter (May-August) average PM2.5 concentration for Motueka was 11.6 µg/m3, with the highest daily value being 25 µg/m3.
Riwaka
Temporary winter PM2.5 monitoring in Riwaka East using a dustmote sensor (ES-642) was completed as part of ongoing surveillance monitoring in this area. The results of the 2022 monitoring indicate that air quality at the Riwaka East location complied with 2021 WHO daily guideline of 15 µg/m3. A comparison of the PM2.5 data found that the peak daily (24-hour) and average concentrations between 2022 and 2021 were very similar. These results suggest that the 2021 and 2022 PM2.5 concentrations were comparable and that the findings from the 2021 investigation are valid.
Read the full report: Riwaka PM2.5 Study winter 2022 Final.pdf (pdf 664 KB)
Council undertook temporary monitoring in Motueka at Ledger Goodman Park using a NES-AQ approved monitoring instrument, monitoring PM10. The highest daily PM10 concentration measured was 32 µg/m3, with a winter average of PM10 of 15 µg/m3.
Council also commissioned Mote Limited to undertake research monitoring at several locations in Riwaka and Brooklyn, using ‘dustmote’ sensors (PM2.5) and monitor meteorological conditions. Sensors monitoring PM2.5 and PM10 were also co-located at Ledger Goodman Park, Motueka. The results of monitoring indicate:
Read the full report: Riwaka, Brooklyn and Motueka PM (pdf 1.5 MB)2.5 Monitoring Network 2021
Council undertook temporary monitoring in Motueka at Ledger Goodman Park using a NES-AQ approved monitoring instrument, monitoring PM10. The highest PM10 concentration measured was 56 µg/m3 on 16 June 2020, with a winter average PM10 of 20 µg/m3.
Council commissioned the National Institute of Water and Atmospheric Research (NIWA) to monitor air quality in Motueka, Riwaka and Brooklyn during May to August 2019. This was to monitor smoke emissions (particulate matter, PM10 and PM2.5) associated with wood burning, traffic and fires.
A network of 22 outdoor air quality sensors – called ODINs (outdoor dust information node) – were installed on street lights and power poles around the area. NIWA used weather station data to track daily air movement and temperatures. The collected data enabled NIWA’s air quality scientists to analyse how much pollution residents are exposed to.
The results of the monitoring indicate:
Read the Full Report: Spatial Variation of PM in Motueka - Winter 2019. (pdf 1.4 MB)
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