Environet Limited is involved in a broad range of air quality projects including development proposals, national and regional projects, research projects and local projects including providing advice on specific discharges and activities.

From a private sector perspective Environet Limited has been involved in providing analysis on potential air quality issues for large scale subdivision proposals as well as numerous assessments of effects for air discharge resource consent applications.

From a national perspective Environet Limited has been involved in the preparation and review of a number of air quality national projects including good practice guides for preparing emission inventories, product profiles for home heating appliances in New Zealand, monitoring and data management and visibility monitoring and management.

Regional projects include preparing emission inventories, health impact studies, assessing monitoring data, source apportionment and visibility studies, evaluating monitoring networks and data requirements, planning work and technical assistance for the development of air quality plans, and providing advice and assessments for air quality management.

Environet Limited has recently completed a major project on determining the cost effectiveness of policy options to reduce PM10 from industrial boilers in Ashburton, Christchurch, Kaiapoi, Rangiora, Timaru and Washdyke. The project, funded by Environment Canterbury, involved an analysis of the costs and benefits of regulations for industrial and commercial boilers.


Case Study 1: Cost effectiveness of policy options for boilers in Ashburton, Christchurch, Kaiapoi, Rangiora, Timaru and Washdyke.


In order to reduce PM10 concentrations from industries Environment Canterbury required further information on the cost effectiveness of different management options for reducing PM10 from the industrial sector. Four policy options were provided by Environment Canterbury. The options involved requiring boiler particulate matter emissions to meet each of the following emission limits: 300 mg/m3, 250 mg/m3, 150 mg/m3 and 50 mg/m3.


In order to determine the industrial boiler profile, Environet Limited under took a survey of existing industries that used either coal boilers, wood boilers, diesel boilers or light fuel oil burners. Information was gathered on the boiler and burner make, model, and size.

Working in collaboration with Powell Fenwick Consultants Limited boiler profiles were established for each location and baseline operating costs were developed.

An evaluation was made of the different measures available to achieve the four emission standards (50, 100, 150 and 300 mg/m3) for each of the boiler classifications. The report included a discussion of the advantages, disadvantages and applicability of each of the four standards.

The capital and operating costs and PM10 emissions reduction associated with converting an average boiler for each existing method to a revised fuel or technology to meet the emissions standards were evaluated. For each site the least cost method for meeting each emission limit was then identified.

An estimate of the revised winter daily PM10 emissions (kg/day) was made for each site for each emission limit.

The cost data was then collated for each area for each emission limit and for each fuel type. An evaluation of the costs and benefits was made by fuel type, to allow for the assessment of the cost effectiveness of applying the emissions limits to specific fuels.

Project Outputs:

The project outputs were written reports for Christchurch, Rangiora, Kaiapoi, Ashburton, Washdyke and Timaru.

These reports included:

  • A description of the measures to achieve the emission limits for the range of boiler types used in each area and for those projected to be used in 2013.
  • A discussion on the practicality of implementing them under different situations.
  • Illustrations of existing boilers and new technology options.
  • An evaluation of the airshed reductions in PM10 emission associated with implementing different emission limits, overall, by scale and by fuel.
  • An evaluation of the capital and operating costs associated with implementing different emission limits, overall, by scale and by fuel.
  • A discussion on the economic life of the measures and costs.
  • A discussion on the uncertainty of the costs and benefits.

To read the full reports on cost effectiveness of policy option for boilers click here: Ashburton, Christchurch, Kaiapoi, Rangiora, Timaru, Washdyke.

Case Study 2: New Zealand Sulphur Dioxide Industrial Inventory.


The Ministry for the Environment needed to provide guidance on the application of the 2005 World Health Organisation (WHO) guidelines for sulphur dioxide (SO2) for air quality management in New Zealand. Some of the issues that had been raised by Regional Councils included inconsistency in the use of WHO guidelines across local government and uncertainties about how these guidelines could be adopted nationally. The first step was to identify industries likely to result in breaches and evaluate the extent of impact of existing SO2 concentrations from industry in New Zealand.

Environet Limited was contracted by the Ministry for the Environment to undertake an Sulphur Dioxide Industrial Emission Inventory.


Environet Limited undertook a survey of over 245 industries throughout New Zealand that had been identified by Regional Councils as having potential SO2 impacts. These included large scale coal-fired boilers, asphalt plants, steel works, power stations and fertiliser manufacturers as well as large scale light fuel oil fired boilers and large-scale waste oil-fired boilers. Emissions calculations were then made to determine daily and annual SO2 concentration from each industry. A list of industry with the potential for significant SO2 discharges in New Zealand was developed. A report was then produced that identified annual and daily SO2 emissions in from the industrial sector in New Zealand.

Project Outputs:

The project outputs included:

  • A spreadsheet with emissions information available at an individual boiler level, collated by region, and nationally with daily SO2 emission estimates by season. Daily data was collated by season to provide an annual emission estimate.
  • A map that indicated the location of the industry in New Zealand with a visual illustration of emissions data (categorised and colour coded e.g., red = 50-60 kg/day).
  • A brief report of inventory that included an analysis of health effects, details of methodology, key findings, and maps.

To read the full report on New Zealand Sulphur Dioxide Industrial Emission Inventory click here.


Air quality monitoring in Nelson showed concentrations of PM10 in excess of ambient air quality guidelines. The 24-hour average guideline of 50 µgm-3 was exceeded on 81 days during winter of 2001. The maximum recorded PM10 concentrations was 165 µgm-3 (24-hour average).

Site evaluation:

Nelson is very conducive to elevated air pollution in some areas. The topography is largely varied with hills and valleys that drain to flatter areas with high density, largely single story housing. Calm still days are common during the winter months.


An emission inventory was carried out to determine sources of PM10 and other contaminants in Nelson. The area of Nelson was broken down into five airsheds and emissions were evaluated for each area.

Air quality management:

Although Environet was the primary author and contributor to the emission inventory assessment, our key role in the project was the evaluation of management options to improve air quality in Nelson. This involved an analysis of existing trends in emission sources as well as detailed modeling of different management scenarios. Management measures include a 10% reduction in industrial emissions, a ban on outdoor burning, a new emissions standard for solid fuel burners (1.5 g/kg), a ban on the use of open fires and no solid fuel burners allowed in new houses or existing houses currently using other heating methods. A detailed description of the air quality problem and method of evaluation of potential solutions is provided in the Environet report on air quality management for Nelson.

In 2009 an evaluation of the long term (2001 - 2008) trends in PM10 concentrations in Nelson showed that the management options adopted by Nelson City Council have been effective in reducing PM10 emissions and concentrations in Nelson's airshed. Nelson City Council is currently on target to meet its Airshed A air quality goals as defined by the straight line path and the 2013 NES. This work is described in an Environet and NIWA report titled 'Assessing long-term trends in PM10 emissions and concentrations in Nelson'.

To read the full report on trends in PM10 in Nelson click here.

To find out more about Nelson City Council visit www.ncc.govt.nz


Southland Regional Council identified a need to develop an air quality monitoring programme for the region.


Environet was contracted to develop an air quality monitoring programme for the region. The following steps were used to develop a robust monitoring programme from which to assess air quality:

  • Urban areas with high-density housing and critical mass were identified.
  • Meteorology and topography were examined for air pollution potential.
  • Local authorities and health professionals were contacted for observations relating to air quality.
  • Estimates of emissions were made for each area based on census heating data, industry information from the Southland Regional Council and population based estimates of VKTs.
  • Emission estimates for different areas were compared based on total quantity of emissions and emission density (e.g., grams per hectare).
  • Urban areas in the region were ranked based on their potential for air quality impacts.
  • Air quality monitoring data for other areas of New Zealand were examined to identify most likely issues for the Southland Region.
  • An initial four-year air quality monitoring programme was designed for the region based on the top four urban areas with the potential for poor air quality.
  • Monitoring methods were evaluated to determine the most suitable and cost-effective method and compliance with national
  • Options were evaluated for purchase versus hire and quotes were obtained and recommendation made.
  • Potential sites were selected within the priority areas based on evaluations of wind direction on days of low wind speed and site compliance with standards e.g., AS 2922.
  • A monitoring regime was established consistent with national specifications.
  • Procedures were established for data collection and provision to Environet for checking.
  • Quality assurance requirements were documented and spreadsheets developed for data analysis.
  • Procedures were developed for data analysis and reporting.

To find out more about Environment Southland visit www.es.govt.nz