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Environment New Zealand 2007 questions and answers: Key findings - Air

Environment New Zealand 2007 publications

What are the key findings on air quality in the report?

In a nutshell

  • New Zealand has good air quality in most locations for most of the time.
  • However, air quality can be affected in about 30 locations, in which around 53 per cent of the population live. 
  • Most air quality problems stem from high winter concentrations of PM10 particulates from coal and wood used for home heating.
  • Auckland also experiences high levels of PM10 particulates from road transport. 
  • Levels of other air pollutants have generally improved or stabilised over time, probably reflecting changes to transport fuels and improved controls on industrial emissions.

Facts and figures

  • Levels of PM10 particulates appear to be falling in the main centres, although the influence of weather makes it difficult to assess trends.
  • During 2005, several airsheds, including Nelson, Timaru, Alexandra, and Christchurch, experienced a large number of exceedences of the ambient standard for PM10 particulates.
  • Home heating is the biggest source of PM10 particulates during winter in all five main centres of population.
  • Nationally, 45 per cent of households in New Zealand burn solid fuels (coal and wood) for home heating. This figure varies considerably on a regional scale, with Auckland burning 32 per cent solid fuels and greater than 75 per cent on the West Coast of the South Island.
  • Levels of other pollutants (nitrogen dioxide, carbon monoxide, sulphur dioxide and benzene) are either at acceptable levels or have decreased with a few exceptions at some individual locations.  For example, roadside and industrial sites in Auckland can experience high levels of nitrous oxide,
  • Levels of airborne lead are very low.
  • The main sources of sulphur dioxide vary across the country. An estimated 86 per cent of winter sulphur dioxide emissions in the Wellington region come from commercial shipping. In contrast the main source in Dunedin is industry, contributing 85 per cent of the emissions.
  • Sulphur dioxide levels dropped in the 1980s and are considered to be low in most parts of the country. In the mid-1990s, roadside levels of sulphur dioxide in Auckland increased, coinciding with an increase in the registration of new and imported diesel vehicles.
  • Transport is the main source of carbon monoxide in New Zealand. Estimates indicate that transport contributes 85 per cent of annual carbon monoxide emissions in Auckland and 51 per cent of winter emissions in metropolitan Christchurch.
  • Levels of carbon monoxide at the Auckland and Christchurch monitoring sites appear to have fallen over the past 10 years. Carbon monoxide levels in Hamilton and Wellington remain below the ambient standard.
  • The main source of oxides of nitrogen in all main centres of population is transport, accounting for about 80–90 per cent of emissions.
  • A significant proportion of oxides of nitrogen emissions in Wellington come from shipping. From 2001 when monitoring begun in Wellington, no exceedences of the national environmental standard for nitrogen dioxide have occured.
  • Christchurch has not exceeded the standard since 1996.
  • Exceedences occur at some Auckland sites.
  • Data indicates the main source of benzene emissions in Auckland is from motor vehicles.
  • In Christchurch, home heating is the main source (51 per cent) followed by road transport (42 per cent). However emissions factors for different sources are not well established.
  • Auckland, Hamilton and residential Christchurch sites monitored for annual levels of benzene were all below both the current ambient guideline and the much lower guideline limit that will take effect in 2010. Monitored roadside Christchurch sites were below the current ambient guideline but above the 2010 guideline limit.

What is the government doing to improve air quality?

A number of initiatives related to the findings of the Air chapter are underway and under development. Examples include:

  • National environmental standards for air quality introduced in 2004. These set health-based standards for ambient air quality for five major pollutants, prohibit the open burning of materials that release dioxins and other toxics, and ensure that methane gas generated by large landfills is flared.
  • Included in the regulations is a design standard for wood burners implemented in 2005. The government continues to work with New Zealand manufacturers to improve performance.
  • Warm Homes programme initiated in 2004. Pilot projects under this programme have seen retrofitting of clean heat into existing homes in Timaru, Tokoroa and Taumaranui. 
  • Improvements in air quality monitoring – over $800,000 assistance from the Sustainable Management Fund to purchase air quality monitoring equipment.
  • Preparation of a national inventory for sulphur dioxide.

A number of transport initiatives, aimed at improving air quality, are also underway and under development. Examples include: