Polluted air is finding its way inside homes in Invercargill, new research shows.
A Niwa study has mapped outdoor air quality for Invercargill and Alexandra and researchers found outdoor air in the most polluted locations contained three times as much particulate matter — from smoke and other pollutants — as the air in the least polluted areas.
Environment Southland has contributed funds for the study in July where 44 air quality clarity instruments monitoring levels of inhalable pollutants were installed within a 2km grid in south Invercargill. Then in mid-August half of the sensors were moved to cover the rest of the city.
Environment Southland air and terrestrial science team leader Nick Talbot said the information gathered showed a broader picture of pollution levels across Invercargill.
This was due to where the wind blew, he said.
"Although south Invercargill has the highest concentrations, not all the pollutants have come from that area.
"Instead the data shows on cold, still nights the pollutants from other parts of Invercargill will accumulate in south Invercargill due to the airflow pushing them from north to south."
Home heating remained the area where people could make the biggest difference to air quality, he said.
"Our message continues to be to burn dry wood hot and bright, don’t bank your fires overnight and make sure to get your chimney cleaned regularly."
The second part of Niwa’s study looked at how much of the recorded pollution was getting into people’s houses by monitoring the air in houses of six volunteers.
Niwa’s principal scientist for air quality Dr Ian Longley said this enabled scientists to work out whether indoor air was being contaminated from inside or outside of the home, or both.
"Even though our homes feel generally secure from the outside world, we found that at least half of the polluted air is finding its way in, whether that be through doors, floorboards, or small gaps in the walls."
They trialled air filtration units in the homes and were able to reduce pollution levels by 50%-90%, he said.
Niwa hoped the study would help councils to better understand how air quality varies in towns and cities and there were plans to replicate it across the country.
The study used Otago Regional Council’s (ORC) air-quality data from Alexandra.
The council data found there were 21 breaches of national air quality standards this winter in Otago including three in Alexandra, four in Mosgiel and 14 in Arrowtown.
ORC air quality scientist Sarah Harrison said Arrowtown had shown the most improvement in reducing the number of air quality exceedances, but there was still room for improvement.
ORC staff were currently reviewing a regional Air Plan and would be consulting on changes to the plan in 2024 and 2025.
The staff were considering whether more rigorous rules were needed to improve air quality in urban areas and would discuss options next year.