Our air 2024

Improvements to the motor vehicle fleet are helping to reduce air pollutant emissions in Aotearoa New Zealand.

That is one of the findings of the Ministry for the Environment (MfE) and Stats NZ’s latest three-yearly update about air quality in Aotearoa.

MfE’s Deputy Secretary – Strategy, Stewardship and Performance, Natasha Lewis, says emissions from motor vehicles (as well as aviation, shipping and rail) were lower in 2019 than in 2012 for all monitored pollutants, except sulphur dioxide.

“Air pollutants from motor vehicle exhaust emissions are reducing per kilometre as a result of vehicle emissions standards, lower-emissions vehicles and improvements in engine technology and fuel quality.”

However, the nation’s vehicle fleet reached its largest size to date in 2022. Annual kilometres travelled by motorists have increased over recent decades.

Road vehicles contribute significantly to different types of air pollution and were the largest source of nitrogen oxides (39 percent) in 2019.

Another main contributor to air pollution is burning wood for home heating, which continues to be a major source of PM_2.5 even though heat pump use has increased.

“Poor air quality in some South Island cities is mainly caused by emissions from home fires. Harmful pollutants from these emissions can be trapped at ground level in valleys and flat areas when there is no wind.”

Our air 2024 shows that air pollution from motor vehicles is still associated with a high number of hospitalisations, premature deaths and substantial social costs. The burden of health impacts caused by air pollution is also greater for some areas and population groups than for others.

“Children, the elderly, pregnant people and people with cardiovascular or respiratory disease are more vulnerable to the impacts of pollution than others.”

Our air 2024 notes that current air quality monitoring doesn’t provide a complete picture of air quality in Aotearoa.

“Councils generally monitor air pollutants in areas that we know are at risk of poor air quality and where people are exposed.”

Our air 2024 also looks at how natural pressures on air quality may change as our climate changes.

“Areas with drier conditions could experience worsening air quality due to higher fire risks and more windblown dust.”

Warmer temperatures and higher carbon dioxide concentrations could increase the suitable growing areas of major pollen-producing species and enable plants to produce more pollen for longer.

“Hay fever affects more than a third of people aged 20-44 years and the number of people affected is increasing.”

Updated indicators

Our air 2024 includes six air quality indicators which Stats NZ updated on 26 September:

• Carbon monoxide concentrations: Data to 2023
• Ground-level ozone concentrations: Data to 2023
• Nitrogen dioxide concentrations: Data to 2023
• PM₁₀ concentrations: Data to 2023
• PM_2.5 concentrations: Data to 2023
• Sulphur dioxide concentrations: Data to 2023

The report also includes two indicators which Stats NZ updated in 2021 and 2023:

• Air pollutant emissions (last updated on 14 October 2021).
• Human health impacts of PM_2.5 and nitrogen dioxide (last updated 23 February 2023).

Pressures on our air

• Air pollutants can be in the form of gases or particulate matter
• Road transport continues to be the main source of nitrogen oxides in Aotearoa
• Burning wood for home heating continues to be a major source of PM_2.5 in Aotearoa
• Human activities – including agriculture, construction and industry – emit a range of air pollutants
• Natural sources of particulate matter in Aotearoa are influenced by climate conditions including wind patterns
• Aotearoa faces growing pressure from light and noise pollution, and the potential intensification of some nuisance odours.

State of our air

• PM₁₀ concentrations continue to improve at many sites, but 66 percent of sites were above the 24-hour WHO guideline between 2020 and 2023
• PM_2.5 concentrations continue to improve at most sites, but all sites were above the 24-hour WHO guideline between 2020 and 2023
• Nitrogen dioxide (NO₂) concentrations continue to improve at most sites, but 60 percent of sites were above the 24-hour WHO guideline between 2020 and 2023
• Sulphur dioxide (SO₂) concentrations continue to improve at most sites, but two of nine sites were above the 24-hour WHO guideline between 2020 and 2023
• Ground-level ozone (O₃) continues to be within WHO guidelines at Patumāhoe (Auckland) and Wellington Central between 2020 and 2023
• Carbon monoxide (CO) concentrations continue to improve at one of three sites, with no sites above the WHO guidelines between 2020 and 2023
• Artificial light at night is increasing in both extent and brightness in Aotearoa, despite the growing number of certified dark sky places.

 Impacts on people and nature

• The impacts of air pollution from motor vehicles are much higher than previously understood, causing health issues for thousands of people each year along with substantial socio-economic costs
• The burden of the health impacts of air pollution is greater for some areas and population groups than for others
• Light, odour and noise pollution can be a major nuisance, cause risks to health and reduce quality of life
• Air and light pollution can harm the health of plants and animals, but we have limited data and evidence on these impacts in Aotearoa.

The outlook for our air quality

• It's highly likely that air pollutants from vehicle exhaust emissions will reduce, while other non-exhaust air pollutant emissions (tyre and road wear) will continue to increase. How air pollution from transport will evolve and impact public health is uncertain (moderate confidence)
• Although use of electric heating is likely to increase, the resulting improvement in air quality will be gradual because people will continue to use the existing stock of wood burners for many years (moderate confidence)
• It's highly likely that some natural particulate matter and aeroallergens will increase because of climate change (moderate confidence).