What is PM₂.₅?
Fine particulate matter (PM2.5) is very small particles in the air, less than 2.5 micrometres in diameter. The main human-made sources of PM2.5 in New Zealand are domestic fires (wood and coal fires for home heating). Other sources include motor vehicles, wind-blown dust, and industry.
When people breathe in PM2.5, it can get lodged deep in their lungs and affect their health. Health impacts from PM2.5 include premature death, hospitalisations (for cardiovascular and respiratory diseases), and restricted activity days.
Almost 1,300 deaths from human-made PM₂.₅ in 2016
In 2016, human-made (anthropogenic) PM2.5 air pollution in New Zealand caused an estimated:
- 1,292 premature deaths (in people aged 30+ years)
- 4,626 hospitalisations for cardiovascular and respiratory disease
- about 1.75 million restricted activity days (days on which people could not do the things they might otherwise have done if air pollution had not been present).
If there was no PM2.5 from human-made sources in New Zealand, then almost 1,300 deaths would have been avoided in 2016.
The 1,292 premature deaths included 118 deaths among Māori, and 46 deaths among Pacific peoples.
Domestic fires were the largest contributor to health impacts from PM₂.₅
Domestic fires were the largest contributor to PM2.5 health impacts in New Zealand in 2016 (Figure 1). Motor vehicles were the second largest contributor.
Figure 1: Number of premature deaths due to PM₂.₅ air pollution in New Zealand in 2016, by source of air pollution (people aged 30+ years)
Largest health impacts of PM₂.₅ were in Auckland and Christchurch
In 2016, the territorial authorities (TAs) with the highest number of premature deaths due to human-made PM2.5 were Auckland City (255 deaths) and Christchurch City (175 deaths) (Figure 2).
Other TAs with high numbers of premature deaths from PM2.5 air pollution included Dunedin City (47 deaths) and Invercargill City (42 deaths).
Figure 2: Number of premature deaths due to PM2.5 air pollution (among people aged 30+ years), by territorial authority (TA), 2016
The lower South Island had higher rates of premature deaths from PM₂.₅
Accounting for population size, territorial authorities in the lower South Island had higher rates of premature deaths from PM2.5 air pollution (Figure 3).
The highest rates of premature deaths from air pollution were in Waitaki District (136 per 100,000 people aged 30+ years), Invercargill City (124 per 100,000), and Timaru District (114 per 100,000).
Figure 3: Premature deaths due to PM2.5 air pollution, rate per 100,000 people aged 30+ years, by territorial authority (TA), 2016
Health impacts from PM₂.₅ have dropped since 2006
From 2006 to 2016, the health impacts from PM2.5 air pollution decreased in New Zealand (Table 1). This included a decrease in the number of deaths, hospitalisations and social costs due to PM2.5. These decreases remained even after accounting for changes in population size.
These results may reflect the considerable improvements in domestic fire emissions that have occurred since 2006.
Table 1: Changes in health impacts from human-made PM2.5 air pollution in New Zealand, 2006 to 2016 (numbers and rates)
Most New Zealanders are exposed to PM₂.₅ above recommended levels
Higher levels of annual average PM2.5 concentrations can impact on people’s health. The World Health Organization (WHO) recommends that annual average PM2.5 levels do not exceed 5µg/m3, in their 2021 air quality guidelines.
In 2016, 81.0% of New Zealanders lived in areas with PM2.5 levels exceeding the WHO 2021 guideline level (Figure 4). The proportion was slightly lower among Māori (77.6%), but much higher among Pacific peoples (94.4%), reflecting differences in where they live.
Figure 4: Percentage of population living in areas with PM2.5 higher than the WHO 2021 guidelines (5µg/m3), total population and by ethnic group, 2006 and 2016
For more information on exposure to PM2.5, see Exposure to poor air quality.