In addition to the key pollutants covered in this report, we have some background information on other pollutants that affect our air quality. However, the representativeness, and in some cases, the quality, of the available data does not allow us to draw firm conclusions on the state of these pollutants at the national level.
We intend to examine these instances on a case by case basis to assess their significance to future environmental reporting. We will consult, assess, and advise ministers and councils on the costs and benefits of improving this information.
See improving environmental reporting data web page for more information.
The other pollutants are compared with the National Environmental Standards for Air Quality (NESAQ) and against the World Health Organization (WHO) guidelines where they differ. Some pollutants are compared with the Ministry for the Environment’s Ambient Air Quality Guidelines when they are not included in the NESAQ or WHO guidelines.
Because carbon monoxide and sulphur dioxide are included in the NESAQ, we discuss them first. Other pollutants follow in alphabetical order.
Carbon monoxide can interfere with the blood’s ability to carry oxygen and can aggravate heart conditions.
In 2012, no breaches of the national standard for carbon monoxide occurred at the 20 sites where it was monitored, with 17 of the 20 sites having concentrations less than half the national standard. The national short-term (eight-hour) standard is the same as the World Health Organization (WHO) short-term guideline. Many of these sites were peak sites and these results suggest that carbon monoxide concentrations elsewhere are also low.
Carbon monoxide is a gas formed by the combustion of fuels such as petrol (from motor vehicles) and wood and coal (from home heating and industry). Natural sources include wild fires.
Sulphur dioxide is associated with respiratory problems, such as bronchitis, and can aggravate the symptoms of asthma and chronic lung disease.
In 2012, none of the nine sites monitoring sulphur dioxide breached the short-term (one-hour) national standard. Of the nine sites, three peak sites exceeded the WHO short-term (daily) guideline for sulphur dioxide. These sites have large emissions from industrial or shipping activities. The two sites influenced by industry emissions (Woolston in Christchurch and Mount Maunganui) exceeded the guideline 54 and 69 times over the year respectively, and the site influenced by shipping (Auckland waterfront) did so 13 times.
The five sites that did not exceed the guideline were a mix of industrial and urban sites.
Sulphur dioxide is produced from the combustion of fossil fuels that contain sulphur, such as coal and oil (used for home heating, industry, and shipping). Industrial sources include milk powder production, thermal electricity generation, petrol refining, aluminium smelting, and steel manufacturing. Natural sources include geothermal activity and volcanoes.
Arsenic can aggravate and is associated with heart conditions, and damage nerves. Arsenic is also associated with cancer of the skin and lungs.
In 2012, annual arsenic concentrations in Wainuiomata (7.1 ng/m3 (nanograms per cubic metre of air)), near Wellington, exceeded the annual health-based guideline set out in the Ministry for the Environment’s Ambient Air Quality Guidelines (2002) of 5.5 ng/m3 by 29 percent.
Other monitoring studies that use screening methods (methods that cannot be directly compared with the annual health-based guideline, but still provide a good indication of concentrations) suggest that arsenic concentrations could exceed the annual health-based guideline in other locations. These locations are in the urban areas of Auckland, Christchurch, Napier, Hastings, Masterton, Blenheim, Nelson, and Timaru (Cavanagh, Davy, Ancelet, & Wilton, 2012).
Some councils are undergoing, or planning to start, monitoring studies to help understand arsenic concentrations in their region. Greater Wellington Regional Council and GNS Science, for example, are conducting a study which may help improve the comparability of results from arsenic monitoring using screening methods with the annual health-based guideline.
Arsenic in New Zealand’s outdoor air comes largely from burning timber treated with the preservative copper-chromate-arsenic. The timber is treated to stop rotting when it is used outdoors, for example, for decking and fencing. Offcuts from building projects are sometimes burnt for home heating. Some industrial activities also emit arsenic.
Lead can have adverse effects on the nervous system and can impair mental development in children and hearing.
Since petrol in New Zealand became lead free in 1996, lead concentrations have been well below the health-based guideline set out in the Ambient Air Quality Guidelines (2002). Because of this, the monitoring of lead has reduced. In 2012, monitoring occurred at one peak site and the results were well below the guideline. These results suggest that lead concentrations elsewhere are also low.
Lead can be emitted from some industrial discharges, such as at metal smelters, and houses or other structures where lead-based paint is being, or has been, removed without the proper safety precautions.
Benzo(a)pyrene (BaP) can irritate the eyes, nose, and throat, and is associated with lung cancer.
Monitoring of BaP has not been routinely undertaken in New Zealand but a small number of discrete studies were undertaken between 2001 and 2010. These studies used screening methods, or were done over short timeframes, so are only indicative of whether the annual health-based guideline set out in the Ministry for the Environment’s Ambient Air Quality Guidelines (2002) has been exceeded.
The limited monitoring of BaP does indicate that BaP concentrations in Christchurch in 2004 and in 2009, and in Timaru in 2007, are likely to have exceeded the annual health-based guideline. These are the only years that monitoring has occurred at these sites (Cavanagh, Davy, Ancelet, & Wilton, 2012).
Some councils are monitoring BaP to help them understand concentrations in their region. These studies will provide more information on high BaP concentrations in New Zealand.
BaP in New Zealand is largely emitted from the combustion of fuels, such as wood and coal from home heating. Vehicle emissions and some industrial processes also emit BaP.
Benzene can have adverse effects on the nervous system and is associated with cancer.
In 2012, annual benzene concentrations in one peak site in Auckland (5.1 µg/m3) exceeded the annual health-based guideline set out in the Ministry for the Environment’s Ambient Air Quality Guidelines (2002) of 3.6 µg/m3 by 42 percent. This peak site was close to busy roads and is therefore influenced by transport emissions – one of the main sources of benzene.
Other monitoring sites are a mix of peak and non-peak sites using screening methods. The results indicate the annual health-based guideline was not exceeded and suggest that only exceptional peak sites exceed the guideline. However, this cannot be confirmed due to the limited monitoring and use of screening methods.
Benzene is a volatile organic compound and motor vehicles and home heating are the main sources of emissions. There are also some industrial activities that emit benzene.