Cold Comfort: Ashburton’s air pollution on track for worst winter in six years

Ashburton has exceeded the high pollution standards twice this year already. Photo: Ashburton Guardian

Ashburton is on track for its worst air pollution winter in more than six years, after breaching the high-pollution threshold twice.

Ashburton has had two incidents of breaching the national air quality standards so far this winter, which already matches its worst winter in recent times, the two breaches in 2018.

The monitoring site located in a residential area on Cambridge Street recorded the breaches on 25 April and 7 June.

It had only two incidents in the five years from 2019 to 2023.

Ashburton's worst year was 2006 when it had 28 breaches but the town steadily improved to record its first year with no breaches in 2020.

In surrounding areas, Kaiapoi had six breaches and Timaru had three, while Washdyke, historically the worst offending site with 35 breaches in 2023, recorded the most with 14 days exceeding the national standards.

Environment Canterbury principal science analyst Teresa Aberkane said home heating was a major contributor to air pollution in Canterbury.

"Weather and topography also play a big part in how long woodsmoke stays in the air.

"During the winter our cold, still, frosty days mean the smoke from home heating isn't blown away overnight and gets trapped until morning when the air warms up or the wind picks up."

ECan monitors air quality at 10 sites across eight airsheds, focusing on particulate matter (PM), specifically PM10 (particles smaller than 10 micrometres in size) and PM2.5 (particles smaller than 2.5 micrometres in size).

These tiny particles are important to monitor because they are small enough to be breathed in, Aberkane said.

When breathed in, PM10 can deposit in the upper airways and cause irritation, as well as affecting the lungs and heart.

PM2.5 can lodge deep into our lungs and reach the bloodstream, potentially leading to serious respiratory, heart and lung problems.

"We've seen significant improvement in Canterbury's air quality over the last two decades, thanks in large part to the efforts of Cantabrians who have switched their smoky burners for lower emission forms of heating, such as heat pumps or ultra-low emission burners," Aberkane said.

LDR is local body journalism co-funded by RNZ and NZ On Air.