Simon Kingham: Urban environment specialist on air pollutants causing premature deaths in NZ

Two air pollutants are quietly contributing to thousands of premature deaths in New Zealand every year, shows a new analysis that’s prompted fresh calls for tougher regulations. While New Zealand’s air quality is generally considered good by international standards, Stats NZ’s newly updated indicator has linked pollution from vehicles and fireplaces to around nine times more early deaths than last year’s road toll. The indicator data was calculated using the latest Health and Air Pollution in New Zealand (HAPINZ) model, which was published in 2022 and used 2006 and 2016 as base years. It focused on two human-made pollutants associated with health risks: PM2.5 - or fine particulate matter measuring fewer than 2.5 micrometres in diameter - and nitrogen dioxide (NO2). While NO2 was mostly linked to traffic pollution, PM2.5 also stemmed from other sources of fossil fuel combustion, such as people burning wood and coal for home heating over winter. In 2016 – the most recent year for which suitable population, health, and air quality data was available – the pollutants were linked to an estimated 13,155 hospitalisations and 3,317 premature deaths. “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,” Stats NZ’s environmental and agricultural statistics senior manager Michele Lloyd said. These ranged from childhood asthma to people needing hospital care for heart and respiratory problems. Source / Stats NZ Of those hospitalisations in 2016, 71 per cent were linked to vehicle emissions, mainly through NO2 exposure, while around a quarter were linked with PM2.5, stemming from home heating. More than two thirds of the premature deaths were also linked to traffic pollution, with another 29 per cent associated with people lighting fires in homes. Across the board, the data showed how much of our population was living in areas with poor air quality, relative to recently-updated World Health Organisation (WHO) guidelines. Between 2006 and 2016, the percentage of our population living in areas where those guidelines had been exceeded rose from 24 to 31 per cent for NO2, while falling from 85 to 81 per cent for PM2.5.   People lighting fires is continuing to drive higher levels of air pollutant PM2.5 over winter in New Zealand. Photo / Warren Buckland Stats NZ insights analyst David Harris said a jump in estimated health impacts from pollution was likely driven by an increasing population, but also rising NO2 exposure – perhaps owing to higher numbers of diesel vehicles on our roads. The data also showed a markedly higher risk for Pacific peoples, likely due to location. The highest numbers of people harmed by the two pollutants could be found in our biggest centres, with some 939 premature deaths and 4633 hospitalisations reported in Auckland alone. Yet, relative to population size, areas in the lower South Island had out-sized impacts: notably the 219 pollution-linked premature deaths per 100,000 people older than 30 in Invercargill, versus Auckland’s rate of 104 per 100,000. Source / Stats NZ Harris pointed out that air pollution itself was made up of a complex mix of gases and particles. But, because it wasn’t possible to individually capture the health impacts of each one, assessments like this were simplified by focusing on key contaminants like NO2. University of Auckland aerosol chemist Dr Joel Rindelaub said the findings were “very much in line with what we already know: air pollution is a major threat to human health. “Over 3,300 premature deaths per year are related to air pollution in Aotearoa New Zealand, that’s more than melanoma, diabetes, colon cancer, and road accidents combined. “Without a serious effort to address the causes of air pollution... these trends are likely to continue.” He saw an urgent need to set a national standard for PM2.5 pollution, something in which our country lagged “way behind” the rest of the world. “Many other countries have acknowledged the harm this pollution can do and have been regulating it for decades,” he said. “In fact, China has been regulating PM2.5 since 2013.” “We could literally be making ourselves dumber by not addressing poor air quality," University of Auckland aerosol chemist Dr Joel Rindelaub says. Photo / Michael Craig Importantly, studies were increasingly suggesting that air pollution could affect our brains, as well as our heart and lungs. “We could literally be making ourselves dumber by not addressing poor air quality.” As well, there was a big need to better understand the health impacts of air pollution indoors, where people spent about 90 per cent of their time on average. While the Stats NZ data was entirely based on outdoor monitoring, Niwa air quality scientist Dr Ian Longley noted that roughly half of the air pollution within our homes and buildings happened to come from outside, with the rest from sources like indoor smoking and cooking. “Covid-19 has not yet changed how we assess outdoor air quality, although the lockdowns and changes to travel patterns have indicated how valuable ongoing monitoring is in times of change and uncertainty,” Longley said. The pandemic had also brought a growth in interest in monitoring indoor air quality, most notably in schools, he said. “This may be fading away now as our Covid amnesia sets in, but it is the growth in indoor monitoring that will allow indoor air, and Covid, to be included in future Stats NZ reporting like this.” - Jamie Morton, NZHSee omnystudio.com/listener for privacy information.