H1: Number of polluted air sheds where exceedances of air quality limits are decreasing

Why are we measuring this?

Clean air is fundamental to life and health. Outdoor air pollution is recognised as an environmental threat to human health and is linked with increased levels of heart disease and stroke, chronic obstructive pulmonary disease, acute lower respiratory infections, and lung cancer. Outdoor air pollution can be an issue in Waitaha Canterbury towns and cities, mainly during the coldest months. Pollutants tend to accumulate when the weather is stable and there is little to no wind. These conditions often occur on cold frosty mornings and cold clear evenings in the winter.

The pollutants of most concern are tiny particles that can be breathed in: particulate matter smaller than 10 microns in diameter (PM₁₀) and smaller than 2.5 microns in diameter (PM_2.5), and benzo(a)pyrene (BaP), and the gas nitrogen dioxide (NO₂).

In designated areas, called airsheds, we compare monitored concentrations of PM and NO₂ with the National Environmental Standards for Air Quality (NESAQ), targets in the Canterbury Air Regional Plan (CARP), and the World Health Organization’s (WHO) ambient air guidelines. 

Burning wood and coal for home heating is the main source of PM₁₀, PM_2.5 and BaP in seven of the eight airsheds we monitor. Air pollution from home heating has reduced as older coal and wood burners have been replaced with lower emitting, modern burners or heat pumps. We expect improvements in BaP along with improvements in PM_2.5.

Motor vehicles are the main source of NO₂. This gas has been monitored in Christchurch for many years at a roadside site (Riccarton Road) and in a residential area (St Albans) with no exceedances of the NESAQ in the last 20 years.

While managing air quality to meet the NESAQ has been our focus for more than 15 years and great progress has been made, the current international consensus is that PM_2.5, a component of PM₁₀, is the more harmful of the two. While our monitoring data show that airsheds in Waitaha Canterbury are largely NESAQ compliant for PM₁₀, improvements are needed in PM_2.5 concentrations.

How do we measure the result?

The NESAQ sets out limits for a selection of air pollutants. Waitaha Canterbury has eight designated air quality management areas (airsheds) under the NESAQ. An airshed becomes polluted if there is more than one PM₁₀ exceedance per year on average over the course of the past five years. An airshed stops being a designated polluted airshed after five years of not breaching the PM₁₀ standard. Waitaha Canterbury airsheds are all towns or cities except for Washdyke, which is an industrial area in the northern part of Timaru.

Air pollution data are collected according to internationally agreed standards and include measurements such as wind speed and direction, and temperature. Continuous data from all monitoring stations in each of the eight airsheds are logged on-site and telemetered back to Environment Canterbury. These data are available to download via Environment Canterbury’s Open data portal. When NESAQ standards are exceeded in an airshed, the public are notified. Information about which agencies monitor air quality, and the standards and guidelines that air pollutants are monitored against, are in the Land, Air, Water Aotearoa (LAWA): Monitoring air quality in New Zealand.

What work have we undertaken to contribute to this outcome?

For managing ambient air quality, there are specific obligations we have as a regional council, including services we deliver under resource management laws and our regional plans. This includes state of the environment monitoring to track whether levels of air pollutants in designated airsheds are reducing in response to New Zealand’s regulatory standards and council policies and rules designed to lower pollutant emissions. Our monitoring enables us to better understand if air quality is improving or getting worse, and/or if it’s being affected by the wind or winter weather. 

Work we have undertaken includes:

• implementing the rules and policies under the CARP to meet the requirements of the NESAQ, including ensuring only compliant wood burners are installed in homes
• helping households reduce emissions through better wood burning for home heating
• providing financial assistance for households to upgrade their home heating through subsidies
• authorising low and ultra-low emissions technology for those who want to continue to use wood for home heating
• working with key partners and stakeholders, such as Ngāi Tahu, territorial authorities, Health New Zealand/Te Whatu Ora, government agencies, suppliers of home heating and industries to support healthy air initiatives and deliver a coordinated, community-focused approach to improving air quality.

Who else plays a role?

The New Zealand government sets laws and standards for managing air quality nationally and regionally.

The Ministry for the Environment/Manatū Mō Te Taiao and Stats NZ/Tatauranga Aotearoa provide a national picture of the environment in regular reports produced under the Environmental Reporting Act 2015. See Our air 2024.

Published insights and data about New Zealand by Stats NZ/Tatauranga Aotearoa also includes environmental indicators of air quality, with some indicators being region-specific.

Check out actions everyone can take to reduce contaminant emissions in air quality in the Waitaha Canterbury region Science Snapshot Update for 2024.

Where can I find more information?

Read about air quality on the LAWA website as well as LAWA factsheets on how air quality is measured, air pollutants – particulate matter, and air pollutants – gases.