Cromwell has made national news this week as one of the “most polluted towns” in New Zealand, having exceeded the National Environmental Standard for air quality more than 20 times in 2021. 

Cromwell, along with Clyde, Alexandra and many other towns across the district are known for smoke during winter months as residential log burners work overtime. 

National Institute of Water and Atmospheric Research air quality scientist Dr Ian Longley explains the Otago Regional Council (ORC) are responsible for routing monitoring of air quality. 

He says the total number of times Cromwell, Milton and Arrowtown together exceeded acceptable standards is almost in total of every other town across New Zealand combined. 

“Data from 2020 showed Arrowtown, Milton and Cromwell were the top 3 most polluted towns in NZ with, collectively, 71 exceedences of the National Environmental Standard, compared to 93 for all other towns across the country. 

“2021 looks like it’s not going to be much different.”

If Clyde and Alexandra were to have their data collected, it could paint a bleak picture for the health of Central Otago’s lungs. 

Ian says the history of persistent poor air quality is why NIWA selected Arrowtown and Cromwell for its “Community Air” project. 

“In this project we are trialling the use of new technologies to allow community members to participate in a more detailed assessment of their town’s air quality. 

“At least 20 outdoor monitors are placed around the town, whilst local residents have air quality monitored in their homes. 

“The project is currently in its first year in Cromwell with over 80 children from Cromwell Primary School and Cromwell College taking monitor home and helping to analyse the data. 

“In Arrowtown the project is now in its third year and is focussing on finding ways to improve air quality in some of the most impacted homes. 

“We will start feeding back results to participants and the wider community from late September.”

Ian says NIWA’s work confirms that overwhelmingly the poor air quality – which is almost completely restricted to cold winter nights and mornings - is caused by residential wood burning. 

“Smoke that is coming out of chimneys is easily able to penetrate into most homes.”

As for the winter farm green waste burnoffs of nearby farming properties, NIWA says it does not have any data specifically focusing on that area. 

The Central App has received a number of complaints to do with large-scale green waste burnoffs, which particularly impacted on Clyde and Cromwell, as well as Alexandra.

“This has not been the focus of our studies to date,” Ian says. 

“However, whereas such burnoffs can be highly visible in some areas, they are generally much further away from most residences and usually occur in the daytime when monitoring data shows air quality in these locations is mostly very good.”

Central Otago District mayor Tim Cadogan says “there are a number of issues at play”.  

“Firstly, is where the air quality standards sit alongside the imperatives of our cold climate?  

“Where does the sweet spot sit between risks associated with air quality and risks associated with losing wood burners. And how will the tests being conducted by NIWA differentiate between smoke caused by woodburners and burnoffs?  

“We really need to get clear science on how much smoke in the towns is contributed to by burn offs.  

“I have little doubt that they are a significant factor, so that issue needs to be dealt with before domestic woodburners are even considered for removal. 

“I was in Clyde last year in minus 10 degrees when the power went out and stayed out and I visited elderly people in homes heated by electricity.  

“It was a dangerous and unsustainable situation, so what will happen if we go 100% electric and the alpine fault goes in winter?

“I also have concerns that organisations such as the Salvation Army supply a lot of firewood to low income families, something that will not be available should log burners be taken away.”

NIWA will release their findings in September.