Media release

Media release: Otago-wide improvements to air quality monitoring - ORC

Tuesday 26 September 2023

In response to new air quality guidelines across the country, ORC has recently been upgrading its monitoring network throughout Otago.

Land, Air, Water Aotearoa (LAWA) announced in June it was updating how it monitored New Zealand’s air quality, by comparing data collected by regional and unitary councils across the country, not only to National Environmental Standards for Air Quality (NESAQ) as has been done since 2005, but now also to World Health Organisation (WHO’s) stricter standards.

ORC’s Scientist – Air Quality, Sarah Harrison, says “With a change in guidelines like this, the air in some Otago towns could be seen as worse, but is not necessarily the case. These new guidelines will simply give Otago a better understanding of potential risks connected to air pollution at lower levels.

"If we can learn more about air pollution through further research and increased efforts, we’ll be better equipped to reduce it across Otago and Aotearoa,” Ms Harrison says.


Particulate Matter

The monitoring focus is on small, airborne solid or liquid particles, known as PM10 and PM2.5; particles with a diameter smaller than 10 and 2.5 micrometres, respectively. The NESAQ currently has a limit for PM10 as the monitoring standard but has signalled a future limit for PM2.5 which will set ORC up well for future NESAQ requirements.

The main difference between PM10 and PM2.5 is that the larger particle sizes in PM10 can originate from natural sources such as pollen and sea salt, or mechanical processes that produce dust.

Ms Harrison says an increase in air quality studies, monitoring sites, and upgrades of instruments are all part of a move to better monitor the finer PM2.5 and focus on combustion-related sources of particulate matter.

There have been many monitoring network upgrades over the last few years, with new instruments now installed at six of seven monitoring sites including Mosgiel and Central Dunedin, the latter both now able to monitor PM10 and PM2.5.

Ms Harrison says, “Previous instruments only monitored PM10; which is mostly from home heating emissions.

“Combustion-related particulate matter is more harmful to peoples’ health as smaller particles can enter the bloodstream after inhalation into their lungs.”


Work being carried out across the region



ORC's air quality team has recently been monitoring wintertime air quality in Ōamaru.

A total of 16 small air quality sensors were temporarily placed on streetlights and power poles for one month to measure particulate matter.

The PM2.5 particles being measured come from combustion-related sources, such as wood burners, industry, and traffic.

While the results of this study are still being processed, they will eventually give a better idea of where PM2.5 concentrations are highest and at what time of the day the peak concentrations occur.

“Staff can then investigate the possible sources of PM2.5 and consider ways to reduce these levels to help improve air quality”, she says.

This study will also be used to assess whether a more permanent air quality monitoring programme is required in Ōamaru.

Temporary air quality sensor being installed in Ōamaru.

Temporary air quality sensor being installed in Oamaru. 



A spatial study, similar to Oamaru’s, was recently completed in South Dunedin. “The information from these studies will help ORC determine future possible monitoring sites,” Ms Harrison says.

Following a recent Health and Air Pollution in New Zealand (HAPINZ) study that found that nitrogen dioxide (NO2) from motor vehicles accounts for over half the health and social costs associated with air pollution, ORC has conducted its own study on nitrogen dioxide and sulphur dioxide, with a short-term monitoring project at the Central Dunedin air quality monitoring site over the winter months in 2022.

Ms Harrison says NO2 is a known traffic pollutant and has health impacts roughly equal to that of PM10 in Otago, however, the extent to which it is harmful was more than expected, and it had not been assessed before in New Zealand.

Health and air pollution in New Zealand 2016 (HAPINZ 3.0): Findings and implications

The study helps inform knowledge around the risk of Central Dunedin exceeding national standards for either pollutant. Results indicated that NO2 concentrations have the potential to exceed the World Health Organization guideline limit, which is a much lower limit than the National Environmental Standard for Air Quality (NESAQ).

Below is a report detailing the results of two air quality projects undertaken during 2022: Nitrogen Dioxide (NO2) and Sulphur Dioxide (SO2) monitoring in Central Dunedin and Ultra-Low Emission Burner (ULEB) testing in Arrowtown.

2022 Air Quality Projects – NO2 & SO2 Monitoring and ULEB testing

Dunedin monitoring site on Clyde Street.

Dunedin monitoring site on Clyde Street.



In Arrowtown during 2022, ORC undertook the Ultra-Low Emission Burner (ULEB) project, to test   burners in seven homes in Arrowtown, to accurately record the emissions from real-life use of these burners.

This information contributed towards national knowledge of the factors that influence emissions and efficiency of wood burners. “Results showed that emissions are very dependent on burning behaviour – which is why it is important to control air flow and to burn dry wood,” Ms Harrison says.

2022 Air Quality Projects – NO2 & SO2 Monitoring and ULEB testing

For the first time, ORC has also been monitoring black carbon in Arrowtown with winter data having recently been collected. “Black carbon is an ultra-fine component of particulate matter and is also a climate change pollutant, as well as a human health hazard,” she says.



A recent spatial study was run with the National Institute of Water and Atmospheric Research (NIWA) in Alexandra to understand more about the movement of particulate matter in Alexandra and compare ORC’s existing monitoring site location with its previous location. Monitoring, using 42 temporary sensors, was completed in July with most of these sensors active from mid-May.

The data collected has helped establish a relationship between the two sites and provided information that can be used for long-term trend analysis. The data will also help to identify a potential future location for full time monitoring.

The move between sites was due to the sale of the property on which the monitoring station was installed. While it can be quite hard to secure the perfect site, and fulfil all requirements, such as keeping a certain distance from buildings and trees, changing of sites is unfortunate and can impact the data record.



Ranfurly, Hawea, Luggate and Kingston have been identified as four locations for spatial studies and monitoring is currently underway in these areas using small temporary air quality sensors on streetlights and power poles to measure particulate matter. The results will give a better idea of where PM2.5 concentrations are highest, at what time of the day the peak concentrations occur, and whether a more permanent air quality monitoring programme is required in these locations.


National monitoring

Since the introduction of the National Environmental Standards for Air Quality (NESAQ) in 2005, monitoring data from regional and unitary councils has revealed air quality in New Zealand to be improving. A recent change to how Land, Air, Water Aotearoa (LAWA) compares monitoring data, now comparing against World Health Organisation’s lower, stricter guidelines, shows there is the potential to reduce health risks more by further combatting air pollution.