Some towns' air quality still poor
While some areas of Otago still face winter air quality exceedances, more than 70% of days across monitored sites during 2024 were classified as "Good" under the Ministry for the Environment's Environmental Performance Indicators.
The 2024 Annual Air Quality Report, recently released by the Otago Regional Council, revealed some towns continued to have challenges in managing their air quality.
ORC air quality scientist Sarah Harrison said Otago recorded 28 exceedances of the National Environmental Standards for Air Quality (NESAQ) for particulate matter with a diameter of less than 10 micrometres (PM10) during the winter months in 2024, compared with 17 exceedances in winter 2023.
The annual report shows PM10 monitoring was conducted in the Alexandra, Arrowtown, Central Dunedin and Mosgiel airsheds in 2024.
Alexandra, Arrowtown and Mosgiel recorded exceedances of the (NESAQ) during the winter months.
"Alexandra and Arrowtown recorded 11 and 16 exceedances, respectively, and Mosgiel recorded one."
PM2.5 (particulate matter with a diameter less than 2.5 micrometres) was also monitored in Arrowtown, Central Dunedin, Clyde, Cromwell, Milton, Mosgiel and Wānaka in 2024.
The sites with the highest annual averages were Clyde and Mosgiel, and the site with the highest 24-hour average was Milton.
"Otago has several towns where air quality is considered degraded during winter, namely Alexandra, Arrowtown, Clyde, Cromwell, Milton and Mosgiel.
"In Otago, the main source of PM is home heating emissions in winter.
"Long-term exposure to PM2.5 and PM10 contribute to the risks of cardiovascular and respiratory conditions," she said.
"In Otago, a lot of PM2.5 comes from burning wood for home heating, and is seen in the data for most towns."
A new PM2.5 monitoring site was installed in Frankton in late 2024, and this data would be reported in the next annual report.
Ms Harrison said black carbon was also a component of particulate matter, and monitoring of it would help improve both our understanding of PM as a product of burning, and black carbon as a health and climate pollutant.
"Monitoring smaller sizes of particulate matter (PM2.5) is a significant step forward," Ms Harrison said.
"These smaller particles pose greater health risks, and by enhancing our network, we're better equipped to inform policy and protect community wellbeing."
Upgrades to the air quality monitoring network would continue throughout 2025, including more co-location and calibration work to improve the accuracy of new instruments.
"These investments ensure the ORC remains at the forefront of air quality management, backed by reliable science and community collaboration," she said.
john.lewis@odt.co.nz
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Otago Daily Times
2 days ago
- Otago Daily Times
Effluent issue unresolved
The Shotover wastewater treatment plant has now discharged the equivalent of about 400 Olympic-sized swimming pools of effluent into the Shotover River and the consideration of its effects has yet to be assessed. The Queenstown Lakes District Council (QLDC) applied for retrospective resource consent from the Otago Regional Council (ORC) for its emergency measures, but the application has yet to be notified and no hearing date has been set. When the QLDC began its "short-term solution" on March 31 it said it was discharging about 12,000cum of wastewater a day, or the equivalent of just under five Olympic-sized swimming pools. That was 81 days ago. The ORC has said under the Resource Management Act its staff need to confirm the application is complete, decide if further information is needed and make a formal notification decision, despite the QLDC's request the application be publicly notified. Regular sampling is done so any impacts on the Shotover and Kawarau Rivers can be monitored and the data is publicly available. But the ORC website confirms "questions have been raised about the impact of the discharge on the Shotover and Kawarau Rivers and what role dilution plays". "Any decision on if this discharge is appropriate and on effects moving forward will be assessed through any consents and compliance processes." University of Otago freshwater scientist Associate Prof Marc Schallenberg said the issues raised were interesting, but warned as well the discharge was "risky business". "This is a very interesting topic," Prof Schallenberg said. "One of the reasons it is interesting is that almost nothing is known about the ecological health of large rivers like the Kawarau. "Because it is so difficult to sample large and fast-flowing rivers, we know very little about them." Typically, assessments were based on water quality without any understanding about the effects on periphyton, invertebrates, or fish. In a river such as the Kawarau, it seemed these ecological components were of little perceived value due to the nature of the river. "However, in terms of downstream drinking water use and recreation, the water quality (especially faecal contamination, pharmaceuticals, etc) is quite important." He said the issue was outside his personal area of expertise, but he supposed the mixing, or dilution, that was happening in the river would be quite rapid and thorough not far downstream from the Shotover confluence. "I guess that by the time it gets to AJ Hackett [Bungy Centre], the sewage will be quite diluted. "But the final concentration of contaminants will depend on the concentrations in the effluent and the amount of water available for dilution. "It's all a messy, risky business where there are downstream users."
Otago Daily Times
12-06-2025
- Otago Daily Times
Air quality, pollution awareness key
The mobile version of ORC's air quality monitor has its PM2.5 sensor in the small box halfway up the mast and its meteorological sensor at the end to measure temperature, humidity, wind speed and direction, and atmospheric pressure to help analyse PM2.5 data. PHOTO: SUPPLIED Otago Regional Council has expanded air quality monitoring, as winter heating challenges continue. The council has also released its Annual Air Quality Report for 2024, highlighting monitoring technology and community engagement in "Otago's commitment to cleaner air and healthier communities". Milton was among several towns in Otago where air quality was considered degraded during winter, along with Alexandra, Arrowtown, Clyde, Cromwell and Mosgiel. The report included data from seven locations monitoring fine air particulate matter (PM) with a diameter of less than 2.5 micrometres (PM2.5), which posed greater health risks to communities. Otago recorded 28 exceedances of the National Environmental Standards for Air Quality for PM10 during the winter months in 2024, compared with 17 exceedances in winter 2023. While those areas still faced winter air quality exceedances, the annual report also showed more than 70% of days at monitored sites were classified as "good" under environmental performance indicators. Long-term exposure to PM2.5 and PM10 contribute to the risks of cardiovascular and respiratory conditions. The main source of PM in Otago came from home-heating emissions in winter. "Monitoring smaller sizes of particulate matter (PM2.5) is a significant step forward," the council's air quality scientist Sarah Harrison said. "These smaller particles pose greater health risks ... we're better equipped to inform policy and protect community wellbeing." Towns including Milton have permanent air quality monitors, but the recent studies have been assisted with the council's new mobile air quality trailer which can be quickly deployed to environmental events including wildfires or reports to the pollution hotline. While winter emissions continue to be a challenge where home heating is the main source of particulate matter, Ms Harrison said the seasonal patterns proved the importance of raising awareness about cleaner burning for heat.
Otago Daily Times
12-06-2025
- Otago Daily Times
Hazards mapped
Balclutha on the edge in 2020. A new Regional Council study has estimated numbers of people and buildings inside Otago's natural hazard hotspots. PHOTO: RICHARD DAVISON A new Otago Regional Council report has mapped out which parts of Otago are most exposed to natural hazards, including floods, earthquakes, landslides and tsunami. River and lake flooding events and liquefaction presented the highest risk across the region, and more than 30,000 people and buildings were potentially exposed. Tsunami and storm-surge disasters remain a risk for large areas containing communities close to the Taieri, Tokomairaro, Clutha-Mata Au, Catlins and Tahakopa rivers and estuaries, where population was a factor in estimating a lower exposure of about 500 people and 1100 buildings. Exposure means a person or building is located in an area where a hazard process might occur — not that they are guaranteed to be affected. The Otago Region Natural Hazards Exposure Analysis was the first to cover the entire Otago region. The analysis assessed exposure to nine key natural hazard types, using regional-scale mapping and modelling to estimate the number of people, buildings, and critical facilities such as hospitals and emergency services were located in areas potentially exposed to natural hazards. The report identified 90 critical community facilities across the region. Dunedin City had the highest overall exposure to flooding, liquefaction and seismic hazards, and joined Queenstown and Wanaka's urban areas with a relatively high exposure to landslides and alluvial fans. "This work is not about predicting when an event might happen," the council's natural hazards manager, Dr Jean-Luc Payan said. "It's about identifying where exposure exists so we can make smarter decisions about resilience, planning and investment." The findings provide a critical foundation for the council's natural hazards prioritisation programme, scheduled to begin in 2025-26 and will help guide long-term planning and land-use decisions, emergency management, regional policy development, Infrastructure and resilience-building projects. While no new hazard mapping was done, the report is based on years of the council's existing hazard data, available through their natural hazards portal. The council will now use the report to identify and prioritise the most at-risk areas for further study and risk reduction work. The natural hazards prioritisation workstream is scheduled to conclude by mid-2026.
