Otago Regional Council (ORC) recorded 37 breaches of national air quality standards this past winter, 16 more than in 2023.

Air quality is generally worse in winter due to an increase in the use of fireplaces for home heating, ORC air quality scientist Sarah Harrison said.

Normally, warm air rises and takes pollution with it, but in winter, cold air gets stuck under the warmer air, holding the pollution near where people breathe, she said.

“Concentrations of particulate matter, an air pollutant measured by ORC, vary year to year and many Otago towns have the geography and climate that allows pollution to build up, rather than disperse.

“Exceedances of the national air quality standards are generally due to a combination of emissions, the environment they are emitted into, and the local weather situation on the day.”

The 37 breaches of ambient air quality were all publicly reported, as required under the National Environmental Standards for Air Quality (NESAQ, 2004).

The NESAQ requires ORC to measure particulate matter emitted into the air with a diameter of 10 micrometres or less (PM10) - about a fifth of the width of a human hair.

ORC is currently refreshing its approach to managing air quality, a statement from the regional council said. 

It is updating its Air Quality Strategy (which provides the overview of how ORC is working to improve air quality) and reviewing its current Regional Plan: Air (which provides the regulations to manage and improve air quality).

PHOTO: Wānaka App