What causes air pollution in Waitaha Canterbury?

Improving air quality starts with understanding where pollution comes from, and which actions will make the biggest difference. In Waitaha Canterbury, winter air pollution is mainly caused by home heating, along with transport, industry and dust.

Smoke from wood burners and open fires releases fine particles into the air, including PM₁₀ and PM_2.5, which can affect people’s health. That is why home heating has been a major focus of our air quality work for many years.

Why home heating causes winter air pollution

Team Leader Climate and Air Quality Science Angie Scott said source information helps explain why some activities have been targeted more than others.

“Air pollution is often the result of lots of small sources adding up,” she said.

“One smoky chimney may not seem like a big issue on its own, but when many households are lighting fires on the same cold, still evening, the combined effect can be significant.”

Cleaner heating rules, burner replacement requirements, education campaigns and support for better burning practices have helped improve air quality across Waitaha.

“We have seen real improvements compared with the past, thanks to years of effort by households, councils and communities,” Angie said. “But winter smoke still affects air quality in some areas, so it remains an important focus.”

Other sources of air pollution (transport, dust, industry)

While home heating has been a key source of winter pollution, it’s not the only activity that affects the air we breathe.

Other sources include transport, industry, outdoor burning, road dust, construction, earthworks, agricultural activities, sea salt and wind-blown dust.

“Different places have different air quality challenges,” Angie said.

“Home heating may be the main issue on cold winter nights, while dust can be more important during dry, windy conditions. Understanding those differences helps us target the right solutions.”

Some sources of local air pollution are also linked with greenhouse gas emissions. For example, industries that burn coal can release both air pollutants and greenhouse gases. Switching to cleaner energy sources, where appropriate, can help improve local air quality and reduce emissions.

“Air quality and climate change are not the same issue, but there are important links between them,” Angie said.

“In some cases, reducing emissions can deliver more than one benefit, including cleaner air locally and lower greenhouse gas emissions.”

How weather affects air quality

Weather also helps explain why air quality can change from day to day.

Emissions are what is released directly into the air from a source, such as smoke from a chimney, exhaust from a vehicle, or particles from dust. Concentrations are what we measure in the air at a particular place and time.  These measurements include emissions from multiple sources that have dispersed and mixed with the surrounding air.

On cold, calm nights, pollution can become trapped close to the ground. On windy or unsettled days, it is more likely to disperse.

“You can have similar emissions on two different nights, but very different air quality results depending on the weather,” Angie said.

“That is why high pollution days are often linked to particular weather conditions, especially in winter.”

What is being done to improve air quality

We use air quality monitoring, emissions information and science advice to track trends and identify where action is needed.

This evidence helps inform regional planning, public education, compliance work, and collaboration with councils, industry and communities.

“Good air quality management depends on good information,” Angie said.

“By understanding where pollution comes from, and how it behaves in the air, we can focus effort where it will make the biggest difference.”

Everyone has a role to play, from using dry wood and keeping fires smoke-free, to reducing dust and supporting cleaner transport and industry. Small changes, made by many people, can add up to cleaner air for our communities.

Burn smoke-free this winter: Learn how to reduce smoke from your fire and improve air quality