Airsheds that exceeded PM10 national standard in New Zealand

By number of days exceeding standard, 2006–2012, number of airsheds


Source: Regional councils of Northland, Bay of Plenty, Waikato, Hawke's Bay, Manawatu-Wanganui, Wellington, Canterbury
West Coast, Otago, Southland; District councils of Marlborough and Tasman; Nelson City Council; Auckland Council

From 2014 Air domain report for the Ministry for the Environment by Statistics New Zealand

An airshed is a geographic area used for measuring air quality standards.

Indicator: National annual average PM10 concentrations

Related topic: Concentration of particulate matter (state)

Indicator definition: A population weighted annual average PM10 concentration indicator from both natural and anthropogenic (human-made) sources.

The long-term (annual) average concentration takes into account both peak and low pollution periods and gives an indication of long-term health risks. Annual averages also represent a larger area and population than short-term (daily) measurements.

Background: Exposure to high PM10 concentrations are linked to adverse health effects such as lung and heart conditions. PM10 is the measured air pollutant that most frequently exceeds national and international thresholds in New Zealand.

Presentation of indicator components: Population weighted annual average concentration of PM10 (micrograms per cubic metre).

Methodology: The national annual average PM10 concentration is estimated using regional council and unitary authority monitoring stations data (54 sites in 2012) and Statistics NZ’s population estimates.

The national average is calculated by using the average concentration for each monitoring site, weighted by the population each site represents.

The population represented by each monitoring site is considered to be the population of the urban area the monitoring site is located in. Where multiple monitoring sites are located within an urban area, the population of the urban area is divided across each of the monitoring sites.

This approach accounts for the difference in the distribution of monitoring sites within New Zealand relative to the represented population. For example, in 2012, 40 percent of monitoring sites were in small towns but populations in small towns represent much less than 40 percent of the total population. An average of all monitoring results would be influenced more by the concentrations in small towns than the proportion of the population it represents.

Monitoring information is only included if the site achieves greater than 75 percent valid data collection and follows good practice approaches (Ministry for the Environment, 2009). This helps ensure the data is representative of the location.

See NIWA’s Indicators for Environmental Domain Reporting report for more information.

Data coverage: Approximately 75 percent of the population in 2012.

Data source: Regional council and unitary authority monitoring data. See Data files page.

Limitations to data and analysis: Rural areas and some urban areas are not included as no air quality monitoring occurs at these locations or the population at the monitoring location is unknown. These unmonitored areas are approximately 25 percent of New Zealand’s population. Currently there is no robust method to estimate air quality concentrations in these areas. This is an improvement that will be considered for future reporting.

Some of the monitoring occurs at sites expected to have the highest concentrations (eg close to road traffic or peak urban areas), and so may not be representative of the whole population it is assumed to represent.
See NIWA’s Indicators for Environmental Domain Reporting report for more information.

Additional information to understand the link between the topic and the indicator: Annual average concentration of PM10 is an indicator of long-term concentration. Short-term indicators are measured by daily concentrations. Long-term concentrations give a better indication of the impact on public health and provide greater representation of area and population than short-term (daily) measurements.

Changes to time series: The sample includes monitoring sites achieving 75 percent valid data. The sample of monitoring sites varies year to year, with additional sites being included if best practice approaches are followed, or omitted if not of adequate standard.


Detailed definitions can be found here:

Data provided by

Ministry for the Environment

Dataset name

Environmental Reporting: Air Domain Report 2014


How to find the data

At URL provided, download 'Excel files'

Import & extraction details

File as imported: Environmental Reporting: Air Domain Report 2014

From the dataset Environmental Reporting: Air Domain Report 2014, this data was extracted:

  • Sheet: Table 8
  • Range: C10:I14
  • Provided: 35 data points

This data forms the table Air Domain Report - Airsheds that exceeded the PM10 national standard on 2+ days a year 2006-2012.

Dataset originally released on:

May 16, 2014

Purpose of collection

The Ministry for the Environment and Statistics New Zealand commissioned NIWA to produce a report that provides information for New Zealand’s Environmental Reporting Series: 2014 Air domain report. This report provides the methodology and results for the national air domain indicators – on-road vehicle emissions, annual average PM10, and health impacts due to exposure to PM10. It also includes information on natural sources of pollutants, and the influence of meteorological conditions on air quality.