Other air pollutants

This section provides data on three air pollutants in selected New Zealand airsheds:

  • nitrogen dioxide (NO₂)
  • sulphur dioxide (SO₂) 
  • carbon  monoxide (CO)

These air pollutants can cause a range of health effects, including respiratory problems.

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Most sites were likely to meet the nitrogen dioxide guidelines in 2013

In 2013, most monitoring sites were likely to meet the World Health Organization (WHO) annual average guideline for nitrogen dioxide (40 µg/m³) (118 out of 122 sites). The monitoring sites likely to exceed the guidelines were close to state highways and busy local roads [1]. 

Council monitoring data shows nitrogen dioxide concentrations in Auckland and Wellington have generally improved over time (Figure 1).

Figure 1 Annual average nitrogen dioxide concentration (µg/m³)

Nitrogen dioxide has been linked to increases in asthma symptoms, and reduced lung development and function in children.  Nitrogen dioxide can also make people more susceptible to infections.

Daily sulphur dioxide guidelines were exceeded at some sites

In 2013, three of the eight monitoring sites for sulphur dioxide exceeded the WHO daily guideline (of 20 µg/m³):

  • Woolston in Christchurch (exceeded 65 times)
  • Auckland waterfront (exceeded 9 times)
  • Washdyke in Timaru (exceeded 1 time).

These sites are influenced by industry  emissions. The Auckland waterfront site is influenced by shipping. The five sites that met the guidelines were a mix of industrial and urban sites.

In 2013, one (Woolston, Christchurch) of the eight monitoring sites for sulphur dioxide exceeded the national short-term (1-hour) standard four times.

Monitoring sulphur dioxide is important, as it is associated with respiratory illnesses such as bronchitis. People with asthma or other chronic lung problems are particularly at risk.

No breaches of carbon monoxide in 2013

Carbon monoxide levels at all 21 monitored sites met the national short-term (8-hour) standard (of 10 µg/m³) in New Zealand in 2013.  Many of these sites were peak sites, suggesting that carbon monoxide levels are low elsewhere also.

Carbon monoxide can harm health, by reducing the blood’s ability to carry oxygen. People with certain types of heart disease are at increased risk. 

Information about the data

Nitrogen dioxide, sulphur dioxide and carbon monoxide

Source: Ministry for the Environment – New Zealand’s Environmental Reporting Series: Environment Aotearoa 2015
Definition: Number of monitoring sites exceeding the WHO long-term (annual) guidelines and national short-term standards for nitrogen dioxide, sulphur dioxide and carbon dioxide. Only selected monitoring stations measure these air pollutants.

For more information on the National Environmental Standards for Air Quality, visit the Ministry for the Environment website.


1. Ministry for the Environment & Statistics New Zealand. 2015. New Zealand's Environmental Reporting Series: Environment Aotearoa 2015. Wellington: Ministry for the Environment.