Pollution study tells story of Rangiora's air

A pilot study conducted by researchers at NIWA may be instrumental in analysing the causes of air pollution and creating solutions. Photo / Getty Images

We are a nation close to the sea, far from other continents, and with a relatively low population density, meaning New Zealand should be an air quality oasis. The country is better off than many others, but our towns and cities still face pollution problems. Scientists at the National Institute of Water and Atmospheric Research (NIWA) are analysing data gathered from a pilot experiment in Rangiora that could help communities measure and control pollution to keep their air healthy and pure.

NIWA staff installed sensors in 14 Rangiora homes in September to detect when occupants were using their woodburners, a significant source of pollution in towns especially in homes using older models.

In addition, the researchers installed six dust sensors, called Outdoor Dust Information Nodes (ODINs), on lamp posts to test the prototype's robustness and data quality. These devices are used to measure varying air quality in different parts of town and how it changes from day to day.

Air quality scientist Dr Ian Longley said the data gathered by these devices could be instrumental in identifying pollution problems and their causes, enabling communities to work with councils to create long-lasting solutions.

"Despite a few glitches which you would expect in any pilot, our dust sensors have performed well and provided us with some consistent and valuable data," said Dr Longley. "This will enable us to further develop this project before the second field test next winter."

Temporary meteorological stations were also established around the outskirts of Rangiora to track changes in wind speed and direction and other measurements of the town's air. Overall, the researchers installed 27 temperature sensors, 11 indoor sensors and six outdoor air quality sensors.

"With the meteorological measurements we made too that's millions of datapoints to interpret," said Dr Longley.

Preliminary results so far have shown:

There is a variation in the amount of woodsmoke across Rangiora but what's causing that variation is not yet clear.

The temperature outside Rangiora's boundaries is slightly lower than in town.

When participants started their wood fires, the temperatures inside their homes rose at different rates. Some homes warmed up at 2°C per hour, while some warmed at about 10°C per hour.

About midnight the air in each house starts to cool and again there was some variation in how fast that occurred.

The trigger points for people to light their woodburners or stop using them

"Now we're moving into the next phase of the research. From these data, and with the continued help of our volunteers, we will carefully construct the story of air quality in one of our country towns to a level of detail that has never been possible before," said Dr Longley.

NIWA researchers plan to expand the pilot program to a follow-up project in Rangiora and research in larger towns for a long term goal of predicting air quality and finding options to influence and change it.