Arsenic concentrations

  • Image, Other air pollutants that affect air quality.

    2018 air indicators are now available

    Arsenic is a toxic chemical element. Airborne arsenic is emitted mainly when timber that is treated with a preservative containing chromium, copper, and arsenic is burned for home heating. Arsenic can aggravate, and is associated with, heart, liver, kidney, and nerve damage. It is also linked to lung cancer.

    We classified Arsenic concentrations as supporting information

    Key findings

    Airborne arsenic concentrations exceeded the Ministry for the Environment’s long-term (annual) guideline at one monitoring site in 2012.

    • Annual airborne arsenic concentrations in Wainuiomata, near Wellington, exceeded the guideline (5.5 nanograms per cubic metre, ng/m3) by 29 percent in 2012 (7.1 ng/m3) but not in 2013 (5.4 ng/m3). Windy conditions and higher winter temperatures contributed to the decrease in 2013.
    • Some monitoring studies suggest arsenic concentrations were ‘likely’ to exceed the guideline in:
      • Auckland
      • Blenheim
      • Christchurch
      • Hastings
      • Masterton
      • Napier
      • Nelson
      • Timaru.

    Definition and methodology

    In New Zealand, airborne arsenic is emitted mainly from burning timber treated with copper chromium arsenic (CCA) preservative. CCA contains chromium, copper, and arsenic to stop wood rotting. Building project offcuts treated with CCA (eg decking and fencing) are sometimes burned for home heating. A 2012 Auckland study showed that 17 percent of households burn offcuts for heating that potentially have been treated with CCA (Stones-Havas, 2014).

    We compare annual concentrations of arsenic (nanograms per cubic metre, ng/m3) with the Ministry for the Environment’s 2002 Ambient Air Quality Guidelines. Exceedances occur when concentrations are above 5.5 ng/m3.

    The Ministry’s guideline recommends a level of protection against health risks from exposure to arsenic. It does not provide complete protection and adverse health effects can occur at lower concentrations.

    Except for the Wainuiomata site, results from arsenic monitoring studies cannot be compared with the guideline directly because they used less sensitive methods or were monitored over short time frames (Cavanagh et al, 2012; Mitchell, 2013). This monitoring provides a good estimate of arsenic concentrations and can indicate if the guideline is likely to be exceeded. Therefore, sometimes we report on arsenic concentrations by ‘likely’ exceedances of the guideline.

    Data quality

    We classified Arsenic concentrations as supporting information.


     This supporting information is a partial measure of the ‘Airborne metals of concern to human health’ topic.


     The accuracy of the data source is of medium quality.

    See Data quality information for more detail.


    Cavanagh, JE, Davy, P, Ancelet, T, & Wilton, E (2012). Beyond PM10: Benzo(a)pyrene and As concentrations in New Zealand air. Air Quality and Climate Change, 46(2).

    Mitchell, T (2013). Wainuiomata arsenic in air investigation, 2012. Greater Wellington Regional Council, Publication No. GW/ESCI-T-13/39. Available from

    Stones-Havas, T (2014). 2012 home heating survey results. Auckland Council technical report, TR2014/011. Available from


    Published 21 October 2015

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