4 days ago
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.
