In New Zealand, air pollution kills thousands of people a year – and it’s not a health burden that is distributed evenly. So why are our national air quality standards so out of sync with the WHO?
Air pollution is, by its very nature, hard to see. Catch a glimpse of oily grey exhaust bouncing out of the bus parked in front of you at the traffic lights, watch the drift of grey smoke trickle out of chimneys on your evening walk, smell, briefly, a tangy burning where a truck was a moment ago. Now, multiply: how many wood burners? How many cars and buses and trucks and motorbikes?
Inevitably, at some point during this multiplication, you will have to breathe in, and when you do, the pollution will be inside you. The two pollutants most commonly tracked around the world are PM10 and PM2.5, standing for “particulate matter”. PM10 are 10 micrometres wide; it would take five to occupy the width of a human hair. “They’re tiny, but they’re relatively large – PM2.5 are four times smaller, they’re the particles that have the most health impacts,” says Paul Hopwood, an implementation advisor for air quality at Environment Canterbury. The PM2.5 particles are so tiny that they can sidle through the lungs and into the blood. When your blood is filled with small particles, not oxygen, your heart has to work harder to keep up – cardiovascular disease is dramatically worsened by air pollution.
“When we breathe in stuff that isn’t oxygen, these things attach to our blood, making it harder to pump around our body and get the oxygen we need,” explains Lucy Telfar-Barnard, a senior research fellow at the University of Otago who has studied the impact of poor indoor and outdoor air quality on health, and advises the New Zealand Asthma and Respiratory Foundation.
Exposure to high levels of air pollution can cause respiratory issues, heart issues and lung cancer. However, it’s not just the obvious respiratory and circulatory system that is affected: as pollution travels through the bloodstream, it can be found throughout the body. Studies have shown that higher pollution levels correlate with students getting lower test scores, and have been linked to severe forms of dementia.
The impacts are wide reaching: according to a first-of-its-kind study from 2022, air pollution from cars causes more than 3,000 premature deaths in New Zealand a year. Research undertaken by councils and the Ministry for the Environment put more hard numbers on it: in 2016, the year with the most recent research, 13,155 hospitalisations for cardiovascular and respiratory disease, 13,229 cases of childhood asthma and approximately 1.75 million days of restricted activity.
Of course, there are rules and guidelines about air pollution, to limit its impact. The WHO publishes air quality guidelines: the latest ones recommend that each year, people are not exposed to more than 5 micrograms of PM2.5 particles, 15 micrograms of PM10 particles and 10 micrograms of nitrogen dioxide, which is mainly produced by vehicles; PM2.5 and PM10 particles come mostly from burning fuel in cars, wood in fireplaces, and industrial sources. In 2016, 81% of New Zealanders lived in areas where these guidelines were surpassed most of the time.
Where air pollution is, and who it affects most
While many stereotypes of polluted cities are in Asian cities with huge industrial hubs that produce goods for much of the world – real-time air quality monitors currently show areas of Delhi, Hong Kong and Jakarta with PM2.5 levels in the 100s – air pollution in New Zealand largely comes from cars and fires, Telfar-Barnard says. “All these different sources have their signatures, so we can tell what types of pollution are high in what areas,” she says.
Air pollution monitoring in New Zealand is done by regional councils, with the data gathered by Land Air Water Aotearoa. Monitors are usually stationary; they look like a big concrete box, and are filled with machines that can detect different contaminants and automatically update monitors around. “It’s like a small shed filled with monitors,” says Hopwood. Commuters in Wellington might be familiar with the monitoring station at the motorway exit on Willis Street; in Christchurch, there is a station on high-traffic Riccarton Road, and others in residential area St Albans and industrial hub Woolston.
That regional data draws a picture of the variety, and inequality, of air pollution in New Zealand. Every single air pollution monitor in the South Island is red, showing that air quality standards for the dangerous PM2.5 have been breached more than four times this year, while the North Island has only a few bright red dots.
There’s one obvious reason for this: the South Island is colder, so people light fires more. “If you’re not burning the wood efficiently, you produce more of these small particles, which can be inhaled deep into the lungs and into the bloodstream,” Hopwood says. Firewood that hasn’t been fully dried, or is being burned in less efficient, older wood burners, is a particular culprit, and it’s the impact of this smoke that the monitoring stations particularly pick up in residential areas. In general, air pollution is worse in winter, as the lower temperature also makes air more dense.
Other causes of uneven distribution of air pollution are due to topography. “Christchurch has an inversion layer, which means all that stuff from wood burners and diesel cars doesn’t dissipate,” Telfar-Barnard explains. An inversion layer is a band of cold air that sits over a place and is trapped by warmer air above it, meaning smoke and particles can’t disperse as normal. “Christchurch had really bad smog, visible air pollution, which is no longer there,” Hopwood says. Moving towards cleaner home heating, as well as improving insulation and installing catalytic converters on cars, has made a difference.
Nelson can also have an inversion layer, with the city bracketed by hills that prevent air moving, and some homes Invercargill and Alexandra (also in an inversion-creating basin) can have pollution three times as much as houses in other parts of town. Wellington, by contrast, with its brisk winds, has better air quality, with particles whisked away from the air above the city.
Because air pollution can dissipate quickly into the expanse of the atmosphere, its effects are localised. Telfar-Barnard has studied indoor air pollution, too: gas stoves and poor-quality wood burners that leak smoke are culprits, but these can be replaced with electric or convection stoves and heat pumps. But since no one lives in a perfectly sealed house, there’s less you can do about outdoor air pollution as an individual.
To Telfar-Barnard, that makes it more urgent for authorities to consider air pollution when making decisions. “Schools and ECE centres should definitely be zoned to be further away from major roads, you can see ECE centres from the motorway in Wellington,” she says. Children and old people are among the demographics most vulnerable to air pollution, so keeping them away from the invisible particles lingering over busy roads is vital. The impacts fall unequally in other ways, too: people working outside – building roads or in construction – are exposed to higher levels of air pollution. Areas with fewer trees and parks, which often means more roads, carparks, factories and air pollution, are usually poorer communities.
Air pollution in New Zealand has reduced – but there’s still a long way to go
While we now know more than ever before about the devastating damage of air pollution, it’s also improved significantly in some ways. In 1972, the Clean Air Act was passed, which led to more information about air pollution being gathered, and limited efforts to reduce industrial pollution. As cars became widespread throughout the second half of the 20th century, the lead used in petrol was a major source of pollution, which had been phased out by the late 90s. Switching away from burning coal as a home heat source (although coal is still used in industrial applications, like making milk powder and electricity) has made a big difference, as has the adoption of emission standards for imported cars, and the shift away from heavy manufacturing in most parts of the country.
Today, there are many policies that could help New Zealand’s air pollution be more in sync with the WHO standards. “Diesel fumes are particularly bad – so any alternatives that get diesel cars off the road is a good start,” Telfar-Barnard says. Electric vehicles produce much less air pollution (there are still some particles produced by the friction of tyres on roads as the vehicles are heavier). A discount provided by the government promoted take-up of EVs, but that has reduced since the subsidy was ended in 2023. Public transport, which moves many more people per vehicle, also reduces air pollution, as does active transport like walking and cycling. (In the short term, though, cyclists and walkers may be exposed to more pollution than those in sealed vehicles, although other health benefits tend to outweigh this effect.)
Another idea that could be implemented more quickly than waiting for mass adoption of electric vehicles is cellphone alerts providing information about when there is higher pollution in your area. This has been trialled in some areas of the UK, Telfar-Barnard says, and allows people to know when a period of high pollution is coming, so they can try to take steps to avoid it.
In this respect, air pollution is unlike water pollution, which is also extensively monitored around the country. When water is contaminated (also sadly common in New Zealand), there is a straightforward action people can take: not going swimming or gathering food. Many people are used to checking sites like Can I swim here? to make a decision about whether to swim or not. But air is harder to avoid, and while it may be possible to change your commute time or route, the best way to respond to poor air quality is harder to determine – especially because the damage is done over time, and won’t necessarily be as obvious as a bout of water-borne diarrhoea three days later.
It helps, then, that local councils are using other tactics to reduce air pollution as a whole. “Christchurch has a big population, and lots of people using wood as a fuel,” Hopwood explains. So reducing air pollution from wood has been essential, something Environment Canterbury has tackled from several angles. It’s accredited trusted “Good Wood Merchants” who provide drier, less smoky fuel. It’s worked with manufacturers to design more efficient wood burners; according to the regional air plan, new burners must meet strict efficiency standards.
Lower-income households can also receive subsidies of up to $5,000 for new wood burners or heat pumps – although this doesn’t apply to tenanted households, although healthy homes standards require landlords to install fixed heating devices such as heat pumps. These changes have been accompanied by the Warmer Cheaper education campaign, which runs each winter, and Hopwood notes that better insulation helps too. “These schemes are beneficial to health – as a council, we have to apply the rules and enable people to keep warm in an affordable way,” Hopwood says. Canterbury has made good progress, but the council can’t do as much about the widespread use of cars, the other source of air pollution.
Ultimately, air pollution is a political question, Telfar-Barnard says. “There are things that can be done, but they all cost money. It’s easy to say ‘you should do this’ but it always requires a budget.” In the meantime, with areas breaching health standards in many major New Zealand cities, people will have to take steps to protect themselves. “If you know you’re in an area with higher risk, if you know you’re someone with health conditions that make you more vulnerable, it makes sense to pay attention to air pollution levels.”
Finally, there are the national air pollution standards. On August 1 this year, Gore recorded a 24-hour average PM10 concentration of 51.43 micrograms. That breached New Zealand’s standards of 50 micrograms, and was further outside more up-to-date WHO guidelines of 45 micrograms. Councils refer to the standards to develop their air pollution plans; ours were last updated in 2011. Since then, research has shown that there is no level of exposure to air pollution that can guarantee that there will be no health effects, and New Zealand is totally out of sync with updated recommendations from the WHO.
Newsroom reported in June that the government employed only one person to work full-time on air quality at the Ministry for the Environment, which is responsible for the national air pollution regulations. The ministry knows levels are out of step; it consulted on changes in 2020, but said it was waiting on the WHO’s revised standards in 2021 and a new health and air pollution report in 2022 before making changes. Two years later, the slow process of waiting for new evidence goes on: last week, the ministry released a report looking at background levels of air pollution from natural sources (like sea salt spray and sulphur dioxide from volcanoes) to consider whether the WHO’s lower thresholds were attainable.
There’s some interest from the government in making these changes. Penny Simmonds, the minister for the environment, told The Spinoff that she had requested further information about the latest evidence on air quality from the ministry. “I will make decisions about the priority of this work after I have received and reviewed this information,” she said in a written statement. Meanwhile, we all have to keep breathing in.
This piece was amended at 4.15 pm on August 12 to clarify the WHO’s standards for PM10. The recommendations are not to exceed 45 micrograms in any 24-hour period. Averaged out over a year, the levels should not exceed 15 micrograms per 24 hours.