Health impacts of exposure to human air pollution

Ōtautahi – Emerging evidence shows exposure to two human-made air pollutants is associated with significant health impacts, StatsNZ said today.

The indicator Human health impacts of PM_2.5 and NO₂ reports on the health impacts associated with exposure to PM_2.5 (fine particulate matter less than 2.5 micrometres in diameter) and nitrogen dioxide from human-made air pollution. It supersedes the previous health impacts indicator, Health impacts of PM₁₀.

The new indicator:

• focuses on PM_2.5 (particulate matter 2.5) and NO₂ (nitrogen dioxide), the air pollutants now known to be of most concern in Aotearoa

• expands the list of health impacts to cover estimated childhood asthma prevalence and hospitalisations associated with exposure to human-made NO₂ air pollution

• presents health impact data at the territorial authority and national levels.

The health impacts in the indicator were calculated using the HAPINZ (Health and Air Pollution in New Zealand) 3.0 model, published in July 2022, which uses base years of 2006 and 2016.

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.

“Clean, healthy air is vital for human health and wellbeing,” StatsNZ environmental and agricultural statistics senior manager Michele Lloyd said.

“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.”

Impacts on human health from human-made air pollution can include premature death, cardiovascular and respiratory hospitalisations, childhood asthma hospitalisations and asthma prevalence, and restricted activity days on which people cannot do the things they might otherwise have done if air pollution was not present.

The two human-made air pollutants of most concern, NO₂ (mainly from vehicle emissions) and PM_2.5 (mainly from combustion), were linked to an estimated 13,155 hospitalisations and an estimated 3317 premature deaths in New Zealand in 2016.

Of the estimated hospitalisations (all ages) attributed to exposure to human-made air pollution in 2016:

an estimated 71 percent (9376 cases) were associated with motor vehicle emissions (mainly NO₂ with some PM_2.5)

26 percent (3375 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:

an estimated 68 percent (2247 cases) were associated with motor vehicle emissions (mainly NO₂ with some PM_2.5)

29 percent (962 cases) were associated with PM_2.5 emissions from domestic fires.

As might be expected, 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:

Auckland – 939 premature deaths (age 30+ years) and 4633 hospitalisations (all ages) and

Christchurch– 462 premature deaths (age 30+ years) and 1448 hospitalisations (all ages).

However, accounting for population size, territorial authorities in the lower South Island had higher rates of premature deaths from human-made air pollution, with Invercargill having the highest rate in the country.