The health impacts of traffic pollution are worse than previously reported. Photo: 123RF
Air pollution is slowly getting better in most places, as New Zealanders gradually switch to cleaner cars and heat pumps.
But the air we breathe is still regularly exceeding World Health Organisation guidelines, and contributing to thousands of premature deaths a year.
The Our Air 2024 report is the first major update to national air quality data since 2021.
Twenty years after national air quality standards were adopted, all sites monitored by a national network of researchers still tested above World Health Organisation guidelines for fine-airborne particles called PM2.5 between 2020 and 2023, the report says.
These fine, airborne particles are small enough to be inhaled and enter the bloodstream, posing health risks.
The 2024 report says the health impacts of traffic pollution are worse than previously reported, because researchers have a better understanding of how nitrogen dioxides and other tiny airborne particles affect people's health, and are monitoring more sites than they were.
It says diesel-powered vehicles have an outsized impact on pollution levels from traffic, and both traffic and pollution from home fires remains a major factor in many urban areas.
Air quality experts who've seen the report said New Zealand's remote, windy location meant it should have some of the best air quality in the world, but gains were slow and at current rates it would be decades before parts of the country met world health guidelines.
Independent specialists Dr Ian Longley and Dr Guy Coulson also said there were wins worth celebrating - such as a significant drop in nitrogen dioxide (from traffic) levels in Auckland's Queen Street due to the substantial reduction in traffic along the busy street where they said many people were exposed to polluted air.
The report says human-made air pollution is contributing to thousands of deaths a year with the main contributors being vehicles and home fires for heating.
However, monitoring focuses on urban areas where most people live and pollution is more likely, meaning there'll be places where air is cleaner that don't feature in reports.
The report at a glance:
More monitoring than before shows worse health impacts
The report says since 2021 "our understanding of the health impacts of fine particulate matter (PM2.5) and nitrogen dioxide has increased. As a result, concentrations of PM2.5 and nitrogen dioxide have been monitored at more sites."
"Evidence in recent years has shown that air pollution has greater health impacts in Aotearoa than previously thought. The health impacts in this report are therefore much higher than those reported in Our air 2021, largely due to an increase in our understanding of nitrogen dioxide exposure," it says.
It notes thousands of premature deaths are related to air pollution every year and more than ten thousand hospitalisations: "Children, the elderly, pregnant people and people with cardiovascular or respiratory disease are more vulnerable to the impacts of pollution than others."
Most sites improving
Particulate matter (PM10 and PM2.5), nitrogen dioxide, and sulphur dioxide concentrations continue to improve at most monitoring sites, the report says. However, many sites have still been reaching levels above World Health Organisation guidelines.
"The report shows that air pollutant levels have decreased at most monitoring sites over the last eight years. However, some sites showed worsening air quality, while pollutant levels at sites where air quality improved were at times above levels in World Health Organisation guidelines," it says.
Cars
Vehicle emissions remain a large source of air pollutants, including PM2.5 (the smallest particles monitored, PM10 being the bigger ones) and nitrogen dioxide.
"Motor vehicle engine and fuel improvements continue to contribute to reductions...despite increases in the total number of kilometres travelled in a year, vehicle fleet numbers, and proportion of diesel vehicles," the report says.
The report says vehicle emissions standards, lower-emissions vehicles and improvements in engine technology and fuel quality all contributed to air improvements, although the increase in the proportion of diesel vehicles would have worsened air quality.
Home heating
The report says burning wood for home heating also continues to be a major source of PM2.5, although there was a 32 percent increase in the sales of heat pumps from 2020 to 2021 and further increases in 2022 and 2023.
South Island cities with little wind - such as Christchurch - are especially affected by poor air quality from home fires, and turnover of home heating appliances is slow, the report notes.