Carbon monoxide concentrations

  • Image, Carbon monoxide concentrations.

    2018 air indicators are now available

    Carbon monoxide is a gas formed by incomplete combustion of fuels, in particular from road motor vehicles and burning wood and coal for home heating. It also occurs naturally, for example, from wild fires. Carbon monoxide can affect human health by interfering with the blood’s ability to carry oxygen and by aggravating heart conditions.

    We classified Carbon monoxide concentrations as a case study

    Key findings

    In 2013, all 21 monitoring sites around the country were within the national short-term standard for carbon monoxide concentrations.

    • Between 2005 and 2013, annual concentrations decreased significantly in 44 percent of monitoring sites (7 of 16) where trend assessments could be conducted. The trend of the remaining nine sites is indeterminate – showing neither a significant increasing or decreasing trend.
    • In 2013, 18 sites had concentrations less than half the standard.
    • Annual average concentrations at selected transport sites (Queen St, Auckland and central Wellington) decreased significantly since 2008.
    • Concentrations at selected urban sites (Glen Eden, Auckland and Upper Hutt, greater Wellington) have remained relatively constant but lower than those at transport sites.
    Note: The four locations show concentrations at different site types – transport (1) and urban (2). They have a continuous and relatively long time series. Results do not necessarily represent the whole location. No health guideline exists for annual average carbon monoxide concentrations. Carbon monoxide concentrations are in milligrams per cubic metre of air (mg/m3).

    Definition and methodology

    The four main human-made sources of key pollutants in New Zealand are burning wood or coal for home heating, road motor vehicle use, industry, and household outdoor burning.

    See Relative contribution of key human-made emissions for more details on emission rates for each key source.

    This case study reports the rolling eight-hour average and annual average concentrations of carbon monoxide, in milligrams per cubic metre (mg/m3). We compare the rolling eight-hour average concentrations with the National Environmental Standards for Air Quality short-term standard. Exceedances occur when concentrations are above 10 mg/m3.

    The standard sets a level of protection against health risks from exposure to carbon monoxide. However, it does not provide complete protection, and adverse health effects can occur at concentrations below the standard.

    Data quality

    We classified Carbon monoxide concentrations as a case study


     This case study is a partial measure of the ‘Airborne gases of concern to human health’ topic.


     The accuracy of the data source is of high quality.

    See Data quality information for more detail.


    Published 21 October 2015

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