Air quality and health

Exposure to air pollution has multiple negative impacts on health and is well-researched globally. There are five common pollutants in New Zealand:

  • Particulate matter
  • Nitrogen dioxide
  • Sulfur dioxide
  • Carbon monoxide
  • Ozone

In Otago, our biggest problem is particulate matter, PM10 and PM2.5. Particulate matter is harmful to human health when inhaled and contributes to causing and exacerbating respiratory and cardio-vascular illnesses. The most vulnerable groups are young children, elderly people, pregnant women, and those with pre-existing conditions.

The World Health Organisation updated their air quality guidelines in 2021, which have reduced the acceptable limits for both PM10 and PM2.5, supporting global research that particulate matter is more harmful at lower concentrations than previously thought.

You can read more about particulate matter on the Ministry for the Environment website, and the modelled impact on health in New Zealand by district.

In Otago, ORC has worked with Southern District Health Board (SDHB) to show that hospital admission rates increased in areas with greater numbers of high pollution days for PM10. More recently, the SDHB has refined this work to show that higher PM10 concentrations increased the risk of acute respiratory infections, highlighting the short-term impact of particulate exposure. Further, higher densities of wood burners lead to increasing this risk.

Find out what we can do about improving air quality in Otago.



In 2019 ORC spoke with Public Health South about possible research into links between wood burning and health risks at a local level in Otago, as air quality monitoring shows domestic heating emissions are still prevalent. 

A 2021 study by Public Health South looked at 812 GP visits from May to August 2014-2018 and found that for some groups, acute respiratory infection risk rose with increasing woodsmoke pollution.  

Also, areas with a higher density of wood burners per hectare had higher rates of GP visits for acute respiratory infections.  

Woodsmoke pollution can be reduced when residents burn only dry wood and keep their fire hot and not smouldering. Further reductions in woodsmoke pollution could potentially be made through thermally efficient homes with good insulation. 

Replacement of older wood burners with no emission appliances or ultra-low emission wood burners will also help improve air quality, are kinder to our air, and to people’s health. 

The study was conducted by the Southern District Health Board and has been published in the New Zealand Medical Journal. 

From an initial analysis of 1870 General Practitioner (GP) visits for acute respiratory infections (ARI) from May to August 2014-2018, 812 visits were selected for the study based on the fact the residents lived within a 1km radius of one of Otago Regional Council’s monitoring sites. 

This information, coupled with air pollution data provided by ORC, was the foundation for the study. 

While impacts of air pollution on health have been well-researched globally, there has never been a study about the effects on an Otago town. As the first of its kind, it will enable the ORC to improve the dialogue between science and monitoring, policy, and physical outcomes.  

The research will also give us good, and importantly, local data as ORC work begins on a new Air Plan.

During summer the air quality we enjoy in Otago is excellent. However, in winter some Otago towns exceed the acceptable level of air pollution under National Environmental Standards for Air Quality (NESAQ) 

Air quality often degrades during winter due to increased domestic heating emissions, cold and calm weather, and the occurrence of inversion layers. For this reason, we have monitoring sites in seven Otago towns: Milton, Mosgiel, Dunedin, Alexandra, Clyde, Cromwell and Arrowtown.  

These monitoring sites measure particulate matter (PM10) concentrations in the air. PM10 are solid or liquid particles in the air, smaller than 10 micrometres, and although they include vehicle and industry emissions, and natural sources such as dust and pollen, the main source in Otago is from home heating emissions. 

ORC is currently upgrading several monitoring sites to monitor for PM2.5 continuously through the year. PM2.5 (particles smaller than 2.5 micrometres) is a more direct indicator of the smaller sizes of particulate matter that are emitted during combustion. 

See the closest monitoring site on our air quality data map to view the latest data.

A hot fire using dry wood should produce very little smoke. If you see dirty smoke coming from your chimney, it is a sign your fire isn’t burning efficiently, or you are burning something toxic. Both result in releasing pollutants into the air we all breathe. 

Burning dry wood means your fire can get hotter more efficiently. You’ll get more heat from each log of dry wood, warming your home faster. It also burns hotter, meaning less pollution from your chimney, which is better for your health and our environment. Find out more at our Burn Dry Breathe Easy page. 

We require consents for wood burners, and depending on where you live, there are different rules for which burners are allowed to be installed.

Find out more about compliant wood burners


Further information

2021 Southern District Health Board study on link between woodsmoke and acute respiratory infections

2007 Southern District Health Board study on hospital admission rates

Health effects of air pollution in New Zealand - Enviro Health Intelligence New Zealand

Particulate matter pollution - Ministry for the Environment

World Health Organisation factsheet on air pollution

World Health Organisation FAQs on new air quality guidelines 2021

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