A new winter air quality monitoring site in Alexandra is needed in the town, after a recent report found the existing one had 23 per cent lower concentrations, giving inconsistent data.

Otago Regional Council air quality scientist Sarah Harrison said, in her report to the Environmental Science and Policy Committee last week, current guidance states that air quality monitoring for regulatory purposes should be conducted at the most polluted location within an airshed.

But, it had only recently been feasible to conduct highly spatially detailed monitoring, and the work revealed how localised the area of peak concentrations in Alexandra was.

While the current site was representative of median or average concentrations across the town, both the current, and the previous site 720m away in Ventry St both under-represent the maximum concentrations in the town, as required by current guidance. 

Sarah recommended that the council relocate their monitoring station again, closer to the ‘hot spot’ area of the town, which included between Ashworth St and Simmonds St.

The State of the Environment (SOE) monitoring for air quality for the year 2023 showed Alexandra, Arrowtown and Mosgiel recorded 17 PM10 exceedances during the last winter. This was consistent with previous years.

Under the Resource Management Act (RMA), regional councils are required to monitor air quality, and to improve it where necessary. The main pollutant of concern is particulate matter (PM), which is a product of combustion.

Long term exposure to PM10 and PM2.5 contribute to the risks of developing and exacerbating existing cardiovascular and respiratory conditions.

Arrowtown had the most exceedances, with 10, as well as the highest maximum daily concentration of 81 micrograms per cubic meter of air (µg/m³). The highest annual mean occurred at Mosgiel, followed by Alexandra with 17 and 16 µg/m³ respectively.