Executive summary

Air quality is a major environmental issue in urban centres worldwide, with adverse effects on both human health and local visibility. The repercussions of compromised air quality span from functional impairments to a spectrum of health symptoms, leading to reduced life expectancy and death. Globally, air pollution causes over seven million deaths annually. In New Zealand, the societal costs attributed to anthropogenic air pollution in 2016 amounted to $15.6 billion. In Auckland, air pollution was responsible for an estimated 939 premature deaths in 2016, and the associated social cost of PM_2.5 and NO₂ air pollution was estimated at $4.45 billion. Air pollution has a detrimental impact on the atmosphere and climate, as some pollutants have warming and cooling properties, contributing to climate change.

Auckland is located on an isthmus between the Tasman Sea and the South Pacific Ocean, benefiting from a relatively clean and dependable airflow due to the absence of any nearby landmasses to the east or west of the city. However, despite these favourable conditions, certain human activities in Auckland still contribute to air pollution levels that exceed national and international standards, posing a threat to public health. 

Transportation, residential home heating, and industrial emissions are the primary sources of anthropogenic air pollutants in Auckland. The Auckland Council is responsible for managing air quality in the region, as mandated by the Resource Management Act 1991 and the National Environmental Standards for Air Quality (NESAQ). To achieve this, the council conducts continuous air quality monitoring, enabling it to assess compliance, develop policies, and evaluate their effectiveness. The council's data collection efforts help to quantify ambient air quality across the region, including spatial and temporal variations. The key air pollutants monitored in Auckland include particulate matter (PM₁₀ and PM_2.5), black carbon, carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), sulphur dioxide (SO₂), and volatile organic compounds.

Data and information from the Auckland air quality monitoring network is reported in multiple ways. Monthly reports are regularly published on the Knowledge Auckland website, www.knowledgeauckland.org.nz. Data is available on the council’s Environmental Data Portal, www.environmentauckland.org.nz and technical reports are produced in specific reporting years. This is the annual data report for 2023 data and its assessment against the NESAQ, Auckland Unitary Plan air quality target, and the 2021 WHO air quality guidelines.

Key findings:

• The annual average PM₁₀ concentration of Auckland in 2023 increased by 1.8% compared to 2022. However, this increase did not exceed the 2021 WHO air quality guideline of 15 μg/m³. It is worth noting that on the individual sites level, Queen Street exceeded the WHO guideline by 37.1%. On 27th July 2023, the Queen Street site recorded one exceedance of NESAQ for PM₁₀ (24-hour average). Our investigation indicated that this exceedance was likely due to the construction activities in the city centre.
• The annual average PM_2.5 concentration of Auckland in 2023 increased by 1.6% compared to 2022. This increase was 26% over the 2021 WHO air quality guideline of 5 μg/m³. The annual PM_2.5 averages for Penrose, Patumahoe, Takapuna and Queen Street sites were higher than the more stringent WHO air quality guideline. The Auckland Unitary Plan ambient air quality targets of 25 μg/m³ for the 24-hour average and 10 μg/m³ for the annual average of PM_2.5 were not exceeded.
• In general, Auckland’s annual mean concentration of NO₂ in 2023 decreased by 8.4% compared to 2022. This is statistically significant (P<0.05). As expected, the highest NO₂ concentrations were measured at the city centre sites. There were no NO₂ national standard exceedance in Auckland. However, on 27 occasions (7%), the 24-hour average NO₂ concentrations exceeded the 2021 WHO air quality guideline of 25 μg/m³.
• The average SO₂ concentration of Auckland in 2023 marginally increased by 0.7% compared to 2022. As found in 2022, the annual SO₂ mean concentration at Customs Street was higher than at the Penrose site. This could be attributed to the higher traffic volume on Customs Street and its proximity to the Port of Auckland, where shipping emissions are likely to be a contributing factor. There was no exceedance of NESAQ and the 2021 WHO air quality guideline for SO₂.
• The average CO concentration at the Khyber Pass Road site increased by 3.5% compared to 2022. This increase is likely due to the 2% increase in traffic volume on Khyber Pass Road. There was no exceedance of NESAQ and the 2021 WHO air quality guideline for CO.
• The average ground level O₃ concentration at Patumahoe in 2023 decreased by 1.7% compared to 2022. Though there were occasional hourly spikes in O₃ mean concentrations, none was above the NESAQ and the 2021 WHO air quality guidelines for O₃.
• In 2023, Penrose's Total Suspended Particulate (TSP) mean decreased by 24.2% compared to 2022, accompanied by a slight reduction in Pb levels, while benzene levels at Khyber Pass Rd and Penrose remained undetectable, and the Crowhurst St site recorded an annual average benzene concentration below the Auckland Unitary Plan threshold, with traces of various VOCs detected at some sites.
• In general, most air pollutants peaked in the morning and late afternoon due to traffic, with the increase between 7am and 9am, and 5pm and 9pm.
• All key air pollutants were highest in winter, most likely due to domestic fires.
• Overall, weekday air pollutants concentrations were slightly higher than weekends due to increased traffic and activities.

Auckland Council technical report, TR2024/11

December 2024

See also

Auckland air quality – 2022 annual data report

Auckland air quality – 2021 annual data report