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Air quality

Air quality

Updated 2 July 2018 12:06pm

Air quality in our region

Although outdoor air quality in our region is generally very good, there are times when it may be poor, for example

  • On calm, cold winter nights in areas where many people use fires for home heating, levels of fine particles from wood smoke can build up to unhealthy levels
  • Near busy congested roads levels of traffic-related air pollutants can be much higher than streets with free-flowing traffic
  • In areas where treated timber is burnt in home fires levels of arsenic may fail to meet health guidelines

See Our Environment at a glance (2014/15) for an overview of air quality in the region.

Where air quality is measured

Greater Wellington measures air quality at several sites across the region within designated airsheds. We have permanent monitoring stations at the following locations:

  • Wellington central (corner of Willis Street and the urban motorway)
  • Lower Hutt (Phil Evans Reserve)
  • Wainuiomata (Moohan Street)
  • Upper Hutt (Savage Park)
  • Masterton (West) and Masterton (East)
Wainuiomata Air Quality Monitoring Station



Air quality monitoring station in Wainuiomata

What we measure

We measure levels of key air quality containments and compare these to the national standards for air quality and other health guidelines.

At most of our air quality sites, we also measure meteorological information such as wind speed/direction, air temperature, relative humidity and barometric pressure.

We also carry out specific air quality investigations from time to time so we can better understand air quality in other locations or monitor for other pollutants such as metals.

Traffic related air quality monitoring

We have a network of micro air quality sites around roadsides in our region that measure monthly levels of nitrogen dioxide using passive diffusion tubes. Results from this monitoring are used to track trends in the impact of traffic emissions on air quality.

Fine particles


Fine particles arise from wood burning, vehicles and other combustion sources. There are also natural sources of particles, such as sea spray and windblown dusts.

Health impacts

Health impacts from breathing in particles can affect a large number of people through restricted activity days and lead to earlier deaths for a small number of people with underlying heart and lung conditions. Health researchers have not established a "safe" level for long term exposure to particles so it is important to keep measuring particle levels, even when the national environmental standards are being met.

A national health and air pollution study (HAPINZ) estimated the total social costs of human-caused air pollution (PM10) across our region as $275.7 million per year from the following sources:

  • 56.9 per cent due to domestic fires
  • 17.4 per cent due to motor vehicles
  • 0.1 per cent due to industry
  • 25.6 per cent due to open burning

Meeting the national environmental standard for PM10

Winter air quality in the Masterton Urban Airshed fails to meet the national environmental air quality standard which only allows one day per year where PM10 levels are above 50 micrograms per cubic metre of air. The number of exceedances varies by year depending on how windy and cold the winter was. The national standard requires the number of exceedances per year to be no more than 3 by 2016 and no more than 1 by 2020. A targeted rates scheme is available to help Masterton residents upgrade their older burners to lower emitting modern burners or clean heating appliances, such as heat pumps.

Number of PM10 exceedance days per year recorded at Masterton monitoring sites. Note monitoring at Masterton East started in 2013.

Masterton wood smoke

Masterton wood smoke

Rules about woodburners and open fireplaces

Greater Wellington doesn’t have any rules about emissions from domestic fires, other than a ban on burning specified materials, such as treated timber, painted or varnished wood, plastics or rubber materials. These types of materials release harmful toxins into the air when burnt.

New woodburners installed on properties less than two hectares in size must meet the national environmental standard’s woodburner performance requirements for emissions and efficiency. Further details and a list of authorised woodburners can be found on the Ministry for the Environment’s webpages.

Under the national environmental standard no new open fireplaces can be installed in the Masterton urban area due to winter air pollution levels.

Nitrogen dioxide

Sources and health effects

Motor vehicles, especially those using diesel, are the main source of nitrogen dioxide (NO2). The health effects of nitrogen dioxide include lung irritation and increased susceptibility to asthma and respiratory infections. Long term exposure to low levels of nitrogen dioxide can affect lung growth in children. In our region we measure NO2 in Wellington central, Upper Hutt and in Masterton. The New Zealand Transport Agency (NZTA) also measure monthly levels of nitrogen dioxide using small tubes at sites around the region as part of their national monitoring programme. Over the past few years our monitoring sites show declining levels of NO2.

Air quality results

Every year we produce a summary report of air quality results that show how air quality measured at our monitoring sites compares to the national air quality standards and guidelines that are designed to provide a set level of health protection for communities.

Real-time air quality data

Air quality measurements are collected every 10 minutes at the monitoring stations and can be viewed on our website. The latest data have not usually been quality checked and therefore are 'raw' or provisional until they have been through the full checking process.

View air quality data:

Wellington central

Lower Hutt


Upper Hutt

Masterton (West)

Masterton (East)

What you can do to improve air quality

The combustion process of petrol and diesel in vehicles releases gases and particulates into the air, which is harmful to those breathing it. Driving an electric vehicle helps improve air quality

For a warm healthy home that produces less air pollution:

To reduce air pollution from our roads:

  • Tune and service your vehicle regularly, especially if it is smoky - a visual check is included as part of your vehicle warrant of fitness
  • Drive more efficiently by smoother driving within the speed limit and removing roof racks and roof boxes when they're not being used. Find out how fuel efficient your driving is using the EECA energywise online calculator
  • Use sustainable transport options