Human health impacts of PM₂.₅ and NO₂

What is measured

This indicator reports on health impacts of human-made (anthropogenic) PM_2.5 (fine particulate matter less than 2.5 micrometres in diameter) and NO₂ (nitrogen dioxide) in Aotearoa New Zealand in 2016. It supersedes the previous health impacts indicator, Health impacts of PM₁₀, reflecting our improved knowledge of human-made air pollutants.

The health impacts in the indicator were calculated using the HAPINZ (Health and Air Pollution in New Zealand) 3.0 model, published July 2022. When the HAPINZ study was commissioned in 2019, 2016 was the most recent year for which suitable population, health, and air quality data was available.

Estimated health impacts include:

• premature deaths (30+ years)
• cardiovascular and respiratory hospitalisations (all ages)
• childhood asthma hospitalisations and asthma prevalence (NO₂ only) (0–18 years)
• restricted activity days (PM_2.5 only) (all ages) (restricted activity days are days on which people cannot do the things they might otherwise have done if air pollution was not present)
• exposure to poor air quality (above 2021 WHO guidelines) among total, Māori, and Pacific peoples populations (all ages).

For the base year 2016, estimated health impacts from human-made PM_2.5 are attributed to key sources in New Zealand, namely domestic fires, motor vehicles, industry, and wind-blown dust. All estimated health impacts from human-made NO₂ are attributed to motor vehicles only.

Estimated health impacts from human-made PM_2.5 and NO₂ are also presented for an earlier base year of 2006, and compared to the estimates of the 2016 base year. Data for further breakdown of health impacts by key sources was not available in 2006.

Why it is important

Clean air is vital for human health and wellbeing and is a basic human right (UN, 2022). Understanding how much air pollution people living in Aotearoa New Zealand are exposed to is important for understanding potential health impacts.

Air pollution comprises a complex mixture of gases and particles. It is not possible to measure or assess the effects of all the individual components of air pollution, so the assessment of health impacts is simplified by focusing on key contaminants. These key contaminants may be acting as proxies for the overall air pollution mixture (WHO, 2016).

NO₂ and PM_2.5 are the air pollutants of most concern in New Zealand. Breathing in NO₂ is associated with health impacts ranging from increased susceptibility to asthma and respiratory illness through to increased risk of premature death (WHO, 2021). When PM_2.5 is inhaled, it can get lodged deep in the lungs and affect our health. There is global consensus that exposure to PM_2.5 causes respiratory and cardiovascular disease, lung cancer, and increased risk of premature death (especially in vulnerable groups such as the young, the elderly, and people with respiratory illnesses) (WHO, 2013). Emerging evidence points to possible links between PM_2.5 and atherosclerosis, adverse birth outcomes, childhood respiratory disease, cognitive impairment, neurological disorders, diabetes, and systemic inflammation (WHO, 2013). 

Even though Aotearoa New Zealand has good overall air quality relative to other countries, we now know that exposure to air pollutants, even at low levels, is associated with significant health impacts. This was one of the key findings of Health and air pollution in New Zealand 2016 (HAPINZ 3.0) (Kuschel et al., 2022a) and has been confirmed in international studies (Stafoggia et al., 2022).

In New Zealand, most human-made NO₂ comes from motor vehicles and most PM_2.5 in the air results from combustion (for example, burning wood for home heating).

Key findings

In 2016:

At a national level:

• Exposure to human-made air pollution from PM_2.5 and NO₂ was associated with an estimated:
  • 3,317 premature deaths (30+ years)
  • 13,155 hospitalisations (all ages), including:
    • 4,626 cardiovascular hospitalisations and
    • 8,529 respiratory hospitalisations (including 845 hospitalisations for childhood asthma, 0–18 years)
  • 13,229 cases of childhood asthma (0–18 years)
  • 1.75 million restricted activity days (all ages).

Emissions from motor vehicles were the main source of health impacts followed by domestic fires. Of the estimated hospitalisations (all ages) attributed to exposure to human-made air pollution in 2016, an estimated:

• 71 percent (9,376 cases) were associated with exposure to motor vehicle emissions (mainly NO₂ with some contributions from PM_2.5)
• 26 percent (3,375 cases) were associated with PM_2.5 emissions from domestic fires.

Of the estimated premature deaths (age 30+ years) attributed to exposure to human-made air pollution in 2016:

• 68 percent (2,247 cases) were associated with motor vehicle emissions (mainly NO₂ with some contributions from PM_2.5)
• 29 percent (962 cases) were associated with PM_2.5 emissions from domestic fires.

At territorial authority (TA) level:

• The estimated number of people who experienced health impacts from human-made PM_2.5 and NO₂ air pollution was highest in the cities with the biggest population sizes, Auckland and Christchurch City.
• However, accounting for population size, the lower South Island had higher rates of premature deaths from human-made air pollution, with the highest rate in Invercargill City (219 premature deaths per 100,000 people, 30+ years).
• Estimated health impacts attributed to vehicle emissions were higher than those attributed to domestic fires across the majority of territorial authorities in Aotearoa New Zealand. The highest premature death rate attributed to motor vehicle emissions was in Christchurch City (141 premature deaths per 100,000 people, 30+ years).
• Overall, the South Island generally had higher estimated health impacts attributed to air pollution from domestic fires, with the highest rates of premature deaths attributed to domestic fire emissions occurring in the lower South Island.

From 2006 to 2016:

The estimated number of health impacts from human-made air pollution in Aotearoa New Zealand increased, driven by an increasing population and increasing NO₂ exposure. The increase in health impacts associated with NO₂ exposure may reflect the increase in the number of diesel vehicles (MoT, 2021). Of note, estimated health impacts from PM_2.5 exposure decreased and this is likely due to improvements in domestic fire emissions (PM_2.5) over this time period (Kuschel et al., 2022a).

In both 2006 and 2016, a large proportion of Aotearoa New Zealand’s population was living in areas with poor air quality (exposure to concentrations above 2021 global guidelines published by the World Health Organization (WHO)). There were further persisting inequities for Pacific peoples, which may reflect differences in where people live as seen in these population density and diversity maps. From 2006 to 2016 the percentage of Aotearoa's population living in areas exceeding the guideline:

• increased for NO₂, from 24 percent to 31 percent, with higher rates for Pacific peoples (increased from 43 percent to 54 percent)
• decreased slightly for PM_2.5, from 85 percent to 81 percent, with higher rates for Pacific peoples (decreased from 97 percent to 94 percent).

Where this data comes from

HAPINZ 3.0, Waka Kotahi NZ Transport Agency, Regional Councils

View data tables

HAPINZ 3.0 data

You can also download a summary data set from the visualisation tool on this page. However, the data from the tool is a summary underlying the presented key findings on this page and does not contain metadata.

Related indicators

Air pollutant emissions

PM_2.5 concentrations

Nitrogen dioxide concentrations

Related content

HAPINZ 3.0

Health and air pollution in New Zealand 2016 (HAPINZ 3.0): Findings and implications

Our air 2021

National Environmental Standards for Air Quality

Why air quality matters

Land Air Water Aotearoa (LAWA)

Environment Aotearoa 2022

About the data

The presented data is based on the results of the updated Health and air pollution in New Zealand (HAPINZ 3.0) study. The study assessed selected health impacts associated with exposure to PM_2.5 (particulate matter less than 2.5 micrometres in diameter) and NO₂ (nitrogen dioxide), which are the air pollutants of most concern in Aotearoa New Zealand (Kuschel et al., 2022a and 2022b).

Health impacts presented on this page are:

Health impacts are estimated based on the air pollutant concentrations a population is exposed to, and the estimated health risks associated with these concentrations.

HAPINZ 3.0 assessed health impacts for long-term exposure (annual average concentrations of PM_2.5 and NO₂). The base year for the study was 2016, with ambient air quality and health incidence statistical data typically averaged over three years from 2015 to 2017 to reduce inter-annual variability.

To determine PM_2.5 exposure, actual ambient monitoring data were used in preference to modelling estimates, with proxy monitoring (value of comparable location) used in unmonitored areas. In areas where only PM₁₀ (particulate matter less than 10 micrometres in diameter) was monitored, ratios of PM_2.5 to PM₁₀ were derived using an empirical relationship based on PM₁₀ monitoring data to estimate PM_2.5 concentrations (Davy & Trompetter, 2020). NO₂ monitoring data coverage was insufficient to undertake a robust assessment of national exposure using monitoring data, therefore NO₂ exposure assessment was based on modelled estimates from the Waka Kotahi Vehicle Emissions Mapping Tool (VEMT) and National Vehicle Emission Dataset (NVED) (Hastings, 2016).

Health data was sourced from the New Zealand Mortality collection and National Minimum Dataset (NMDS) provided by the Ministry of Health. Population data was based on the Stats NZ estimated resident population as at 30 June 2016. All data was collated and analysed by census area units (CAUs), based on the 2013 Census boundaries – this is the finest spatial disaggregation possible for national health incidence statistics. Results were aggregated by different spatial groupings, from airshed to national level (Kuschel et al., 2022b). We present HAPINZ 3.0 health impact results at territorial authority and national level.

The proportion of health outcomes attributable to air pollution was assessed by applying pollutant-specific exposure-response functions (a risk ratio showing the relative increase in health effect for every increment of air pollution) and the exposure estimates. The exposure-response functions were developed specifically for New Zealand exposure (Hales et al., 2021).

Health impacts of PM_2.5 and NO₂ - Datainfo+ provides further information.

For the 2016 assessment, HAPINZ 3.0 attributed PM_2.5 and NO₂ air pollution to key emission sources in New Zealand. The data focuses on human-made sources of air pollution because these can potentially be controlled and changed.

All impacts of NO₂ were assigned to on-road (registered) motor vehicles, as these are estimated to be responsible for approximately 90 percent of all NO₂ exposure in urban areas (Kuschel et al., 2022a; Xie et al., 2019).

PM_2.5 air pollution was attributed to the following human-made sources, based on Aotearoa New Zealand derived source apportionment ‘fingerprints’:

• domestic fires used for home heating – based on a biomass burning fingerprint (where available) or an empirical method based on PM_2.5
• motor vehicles encompassing exhaust, brake/tyre wear, and re-suspended road dust – based on a motor vehicle fingerprint
• industry – based on a local industry fingerprint (where available)
• windblown dust from sources such as construction, land use, industry, and the movement of motor vehicles (for example, road abrasion, suspension, and re-suspension of surface material) – based on a crustal material fingerprint.

To assess the change in health impacts between 2006 and 2016, the study used the HAPINZ 3.0 health effects model to estimate health impacts from all human-made PM_2.5 and NO₂ sources in 2006 (no source attribution available). The HAPINZ 3.0 methodology was applied to create a PM_2.5 exposure dataset for 2006 to fill in the gaps in the monitoring record and the model was populated with actual population and health data for 2006. NO₂ exposure in 2006 was estimated by scaling the 2016 NO₂ exposure values by a calculated factor based on the overall average change in concentration across sites. All NO₂ exposure was assumed to be human-made only.

Detailed methodology and findings of the HAPINZ 3.0 study, including history and study limitations, can be found in the following reports: Health and Air Pollution in New Zealand 2016 (HAPINZ 3.0): Volume 1 – Findings and implications  and Health and Air Pollution in New Zealand 2016 (HAPINZ 3.0): Volume 2 – Detailed methodology. The HAPINZ 3.0 health effects model and user guide can be downloaded from the HAPINZ 3.0 data and publications website.

The HAPINZ 3.0 study also estimated the social costs from human-made air pollution in New Zealand; the key findings can be viewed on the HAPINZ 3.0 website.

Data quality

The accuracy of the data source is of medium quality.

Health impacts of PM_2.5 and NO₂ are a direct measure of the ‘Impacts on public health’ topic and a partial measure of the ‘Economic impacts’ topic.

Stats NZ and the Ministry for the Environment must report on topics related to the five environmental domains: air, atmosphere and climate, fresh water, land, and marine. These topics identify key issues within each domain.

Topics for environmental reporting describe the topics for each domain.

Data quality information has more information about the criteria we use to assess data quality.

References

Davy, P. K., & Trompetter, W. J. (2020). An empirical model for attributing sources of particulate matter. Supplementary report prepared for HAPINZ 3.0 by GNS Science, GNS Science consultancy report 2020/33, Institute of Geological and Nuclear Sciences, NZ, November 2020.

Hales, S., Atkinson, J., Metcalfe, J., Kuschel, G., & Woodward, A. (2021). Long term exposure to air pollution, mortality and morbidity in New Zealand: Cohort study. Science of the Total Environment.  801:149660. https://doi.org/10.1016/j.scitotenv.2021.149660

Hastings, K. (2016). Local Authority Vehicle Emission GIS Mapping, Prototype Development for Four Local Authorities. Prepared for Waka Kotahi NZ Transport Agency, 26 September 2016. Jacobs New Zealand Limited. 

Kuschel, G., Metcalfe, J., Sridhar, S., Davy, P., Hastings, K., Mason, K., Denne, T., Berentson-Shaw, J., Bell, S., Hales, S., Atkinson, J., & Woodward, A. (2022a). Health and air pollution in New Zealand 2016 (HAPINZ 3.0): Volume 1 – Finding and implications. Report prepared for Ministry for the Environment, Ministry of Health, Te Manatū Waka Ministry of Transport and Waka Kotahi NZ Transport Agency, March 2022. https://environment.govt.nz/assets/publications/HAPINZ/HAPINZ-3.0-Findings-and-implications.pdf 

Kuschel, G., Metcalfe, J., Sridhar, S., Davy, P., Hastings, K., Mason, K., Denne, T., Berentson-Shaw, J., Bell, S., Hales, S., Atkinson, J., & Woodward, A. (2022b). Health and air pollution in New Zealand 2016 (HAPINZ 3.0): Volume 2 – Detailed methodology. Report prepared for Ministry for the Environment, Ministry of Health, Te Manatū Waka Ministry of Transport and Waka Kotahi NZ Transport Agency, March 2022. https://environment.govt.nz/assets/publications/HAPINZ/HAPINZ-3.0-Detailed-methodology.pdf

MoT (2021). Te tatauranga rāngai waka a tau 2020 | Annual fleet statistics 2020. Te Manatū Waka Ministry of Transport, Wellington, NZ, December 2021. https://www.transport.govt.nz/statistics-and-insights/fleet-statistics/sheet/2020-annual-fleet-statistics

Stafoggia, M., Oftedal, B., Chen, J., Rodopoulou, S., Renzi, M., Atkinson, R.W., Bauwelinck, M., Klompmaker, J.O., Mehta, A., Vienneau, D., Andersen, Z.J., Bellander, T., Brandt, J., Cesaroni, G., de Hoogh, K., Fecht, D., Gulliver, J., Hertel, O., Hoffmann, B., Hvidtfeldt, U.A., … Janssen, N. A. H. (2022). Long-term exposure to low ambient air pollution concentrations and mortality among 28 million people: results from seven large European cohorts within the ELAPSE project. The Lancet Planetary Health., 6 (1), e9-e18. https://doi.org/10.1016/s2542-5196(21)00277-1

United Nations (2022). The human right to a clean, healthy and sustainable environment: resolution / adopted by the General Assembly. 76^th Session: 2021-2022. 26 July. [Online: https://digitallibrary.un.org/record/3983329?ln=en]

WHO (2013). Review of evidence on health aspects of air pollution: REVIHAAP project: technical report. WHO Regional Office for Europe. https://www.who.int/europe/publications/i/item/WHO-EURO-2013-4101-43860-61757

WHO (2016).  Health risk assessment of air pollution – general principles.  World Health Organization, 2016.  https://apps.who.int/iris/handle/10665/329677

World Health Organization (2021). WHO global air quality guidelines. Particulate matter (PM_2.5 and PM₁₀), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. https://www.who.int/publications/i/item/9789240034228

Xie, S., Crimmins, P., Metcalfe, J., Sridhar, S., Wickham, L., & Peeters, S. (2019). Auckland air emissions inventory 2016. Auckland Council technical report, TR2019/024. https://knowledgeauckland.org.nz/media/1558/tr2019-024-auckland-air-emissions-inventory-2016.pdf

Archived pages

Archived February 2023:

Health impacts of PM₁₀ – published October 2018