LAWA Air Quality - National Picture 2024

 

Published: 6 June 2024

 

Why air quality is important

Breathing good quality air is fundamental to our well-being. The health impacts of polluted air are wide-ranging and the elderly, young people, and vulnerable groups are affected the most. Good air quality is also important for ecosystem health. For example, dust on plants can hinder photosynthesis.

 

Air quality context in New Zealand

New Zealand has relatively good air quality due to its low population density and island geography.  Over the last 15 to 20 years, the air pollutant of most concern in many parts of New Zealand has been particulate matter (PM) from burning wood and coal. Concentrations of PM have been reducing in the majority of monitored places. The World Health Organization (WHO) Air quality guidelines updated in 2021 and the Health and Air Pollution in New Zealand report released in 2022 show health impacts from motor vehicle emissions (nitrogen dioxide) are more significant than previously thought.

 

What is monitored and shown on LAWA?

To help safeguard air quality in New Zealand, outdoor air is monitored for key air pollutants by regional councils and unitary authorities. Long-term monitoring sites track levels of air pollutants generated from different activities such as residential, industrial, and traffic sources.

LAWA shows air quality information from around 62 active and 84 historical monitoring sites at towns and cities throughout New Zealand's 16 regions. Many, but not all, monitoring locations focus on areas known or suspected to have poor air quality. As such the data on LAWA are not intended to be representative of overall air quality in New Zealand. They are used to inform our understanding of air quality and identify the main contributors to poor air quality at local levels. 

Most monitoring sites measure particulate matter (PM), which are airborne particles that are both naturally occurring (e.g. windblown dust, pollen and sea salt) and produced by human activities (e.g. burning of fuels). The size of PM plays an important role in how PM impacts on our health. Coarse and fine sized particles less than 10 micrometres (µm) in diameter (measured as PM₁₀) can enter our airways. The fine sized particles under 2.5 µm (PM_2.5) can go further and lodge deep into our lungs with the ultrafine particles (less than 0.1 um) entering the bloodstream.

Gas pollutants, including sulphur dioxide (SO₂), carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃) and benzene are monitored by some councils, mainly city sites where traffic and industry are often the main sources.

Air quality data are reported against standards and guidelines. The two main standards and guidelines used on LAWA are:

• National Environmental Standards for Air Quality 2004 (NES-AQ) – these regulations are made under the Resource Management Act to provide a minimum level of health protection for people in New Zealand. 

• World Health Organization Air quality guidelines 2021 (WHO 2021) – these newer guidelines are informed by recent scientific understanding on health impacts from air pollution. They are non-regulatory.

 

Particulate matter - current state (2023)

In parts of the country, many people are exposed to relatively high levels of PM in winter, produced by wood and coal burning for home heating. In these areas, PM levels can exceed national air quality standards or guidelines, usually on colder winter days and nights when there is no wind to disperse the PM.

• PM₁₀ is the most monitored air quality indicator. It tells us about the particulate matter in the air from both the coarse particles (ranging from 2.5 – 10 µm in size) and smaller fine particles (PM_2.5, with a diameter of 2.5 µm or less).  

• PM_2.5 is generated by combustion (e.g. burning wood, coal and diesel) and is likely to be more harmful to our health. The ability to measure specifically for PM_2.5 enables us to understand more about which areas pose a higher health risk compared to measuring PM₁₀ alone.

At sites that monitor both PM₁₀ and PM_2.5, results show that PM_2.5 concentrations frequently make up a large proportion of the PM₁₀ concentration when combustion sources are present.

 

Key findings

• Daily average PM₁₀ concentrations met the NES-AQ in nine of the 15 monitored regions. Just over three-quarters of all PM₁₀ monitoring sites met the daily NES-AQ (Figure 1).

• PM_2.5 was monitored in 13 regions, with only one region (Northland) meeting both the annual and daily average WHO 2021 non-regulatory guidelines. Less than a quarter of all PM_2.5 monitoring sites met the daily WHO 2021 guideline (Figure 1).

• The highest PM_2.5 concentrations were found in towns such as Tokoroa, Kaiapoi, and Timaru, where winter woodsmoke from home heating is not well dispersed due to topography and weather conditions.

 

LAWA National Air Quality State (2023)

Figure 1: Comparison of monitored sites that met or did not meet the daily PM₁₀ standard (NES-AQ) and PM_2.5 guideline (WHO 2021) in 2023. The location of sites, and whether they met the daily PM₁₀ standard or PM_2.5 guideline, are shown on the maps.

 

The World Health Organization (WHO 2021) guidelines are more stringent than the previously reported WHO 2005 guidelines. Consequently, there are more PM_2.5 results in exceedance of the new guidelines than when we reported against the previous guidelines – the change in reporting is based on improved understanding of the health impact of breathing fine particles. The WHO advises the vast majority of the world’s population breathes air that exceeds the guidelines for PM_2.5. While many councils monitor and report on PM_2.5, it is not a current regulatory requirement in New Zealand.  Note: The Ministry for the Environment is considering how best to include PM_2.5 in New Zealand’s outdoor air quality regulations. We expect, in time, PM_2.5 will be monitored at more sites, and these sites will be displayed on LAWA.

 

How has air quality (particulate matter) changed over time?

 

Key findings

• Most monitored towns and cities show improved air quality over the last ten years (2014–2023). Almost three-quarters of the 45 monitoring sites where there was enough data for trend analysis showed improving air quality (Figure 2).

• Eight sites had an indeterminate trend. This means there is not enough statistical certainty to determine if the air quality is improving nor degrading.  

 

LAWA National Air Quality PM₁₀ 10-year Trends (2014-2023)

Figure 2. Ten-year trend results at sites monitored for PM₁₀ using data from 2014–2023. The location of these sites and trend result is shown on the map. Thirteen sites did not have enough data available to calculate a 10-year trend and are not included in the results above. This happens when monitoring started after 2014, there are large data gaps, or there were changes to the monitoring instruments.

 

Of the 46 monitoring sites that met the national standards (NES-AQ) for PM₁₀ in 2023, 26 sites (or 57%) have had improving air quality, three sites (or 7%) had declining air quality and seven sites (15%) had indeterminate trends. The remaining 10 sites did not have enough data available to calculate a trend.    

Of the 12 monitoring sites that did not meet the NES-AQ for PM₁₀ in 2023, seven sites (or 58%) have had improving air quality, and one site had declining air quality over the last 10 years. The trend was indeterminate at one site and three sites did not have enough data to determine a trend. 

 

Gas pollutants

Gas pollutants are monitored mainly at city sites in New Zealand where traffic and industry are often the main sources. The levels of gas pollutants typically meet the national standard (NES-AQ). However, levels of nitrogen dioxide (NO₂) are usually higher and do not meet the WHO 2021 guidelines at larger city sites close to busy transport corridors. Nitrogen dioxide monitoring results can be found at sites in Auckland, Wellington, Masterton, Christchurch and Hamilton.

The NZ Transport Agency Waka Kotahi has an extensive monitoring network on highways around New Zealand. More information can be found here.

 

Air quality monitoring and reporting

Monitoring data are used by scientists and decision-makers to assess the state of air quality, identify what impacts it, and understand how it is changing over time.  This informs the policies and actions needed to improve air quality and benefit people's health.  When PM₁₀ standards are exceeded, councils notify the public and work towards improving the air quality.

 

Explore more on LAWA

Click on the Regions tab to explore summary information for each region. Then click the Towns tab to find out about the main contributors of air pollutants and how air quality changes over the seasons.  Access monitoring site information either by clicking on a site dot on the map to the left of the LAWA main screen (desktop and tablet users), or by navigating menus to the region, then town, and then site of interest.  The organisation responsible for monitoring an individual site can provide further context to the results shown here.

 

National environmental reporting on air quality

The Ministry for the Environment and Stats NZ provide a national picture of the environment in regular reports produced under the Environmental Reporting Act 2015.  Our air 2021 was published on 10 December 2021.

Our air 2024

 

Stats NZ collect information to publish insights and data about New Zealand, including environmental indicators of air quality.

Stats NZ: Air indicators

 

The HAPINZ 3.0 report was released by Ministry for the Environment, Ministry of Health, Ministry of Transport, and NZ Transport Agency Waka Kotahi on 6 July 2022. HAPINZ 3.0 is the latest update of this report series and assesses the air pollution health impacts experienced by New Zealanders for 2016.

A significant finding was that of the more than 3,300 deaths associated with anthropogenic air pollution, more than 60% were associated with nitrogen dioxide (NO₂) pollution – largely from motor vehicles, while the other 40% were associated with fine particulate (PM_2.5) pollution – largely from home wood burning. The report acknowledged the overall improvements in particulate matter concentrations and the increase in regional and unitary council monitoring of PM since the previous HAPINZ 2.0 report.

HAPINZ 3.0 report

 

What can I do?

We all have a role to play in the quality of our air:

• Use clean heating

• Burn smokefree

• Reduce outdoor burning

• Reduce transport emissions

• Report pollution to your local council