New focus on air pollution
Case study will be hard-hit Timaru
One of New Zealand’s worst towns for air pollution will be the focus of a new study. While New Zealand’s air is generally clean, many cities and towns — including Timaru — are blighted by poor quality each winter as households turn to woodburners to keep warm.
The latest data showed burning coal and wood made the biggest contribution to annual levels of particulate matter (PM).
As these small pollution-borne particles hang in the air, they could be inhaled and increase the risk of illnesses.
But it wasn’t just households to blame, but factory fumes and smog from streets and highways.
Other nasties lingering in urban centres included carbon monoxide, nitrogen oxides and volatile organic compounds — which could mix to form a troubling greenhouse gas called tropospheric ozone.
The best way to drive down urban pollution, scientists say, is to first find where it’s coming from.
Air quality experts have previously done this through timeconsuming, bottom-up accounting exercises.
“There are a range of air pollution computer models that can take a prescribed emissions map for a city and simulate what the resultant pollution levels around the city would be,” explained Dr Greg Bodeker, of Alexandra-based firm Bodeker Scientific.
“While knowing the level of pollution is useful, knowing where that pollution came from is far more valuable since city officials can then act to close down, or mitigate, those sources.”
His team aimed to develop a new way to create maps of pollution sources.
“The method uses measurements of particulate matter in the air around a town or city, a state-of-the-art computer model that can simulate the distribution of air pollution for given emissions, and a smart mathematical technique to infer emissions from measured concentrations.”
Specifically, they’d use an approach called inverse modelling — which effectively ran current models backwards. This took real-world measurements of pollution and then inferred what the pollution map must have looked like, while building in the uncertainties on the maps.
The goal of the two-year project, supported with a million-dollar grant from the Ministry of Business, Innovation and Employment’s Endeavour Fund, would figure out precisely how to do this.
“Small uncertainties in transport pathways of air parcels from their sources to where they are measured can result in large uncertainties in the inferred pollution emissions fields,” Bodeker said.
“This is the first time this inverse modelling approach has been applied at a city scale and the first time that the goal has been to develop an operational capability.”
The testing ground would be Timaru, which recorded some of the highest winter-time levels of pollution in Australasia. Last year, the South Canterbury town had 48 nights where PM levels crossed the threshold set by the World Health Organisation (WHO).
“After testing and proving our new technology through this project, we will export it globally through a newly established commercial entity as a service to megacities around the world that are hampered by poor air quality,” Bodeker said.
“In this way, in addition to tackling a domestic problem of winter-time particulate matter pollution in local towns and cities, New Zealand ingenuity will be exported globally to address an increasingly urgent global problem.”
According to the WHO, air pollution causes 1.8 million deaths from lung disease and cancer every year. Unless the world tackled climate change, figures would rise by 60,000 globally by 2030 and by 260,000 by 2100.
Other groups working in the project included Niwa, Environment Canterbury, Canterbury University, Otago University, Germany’s Karlsruher Institute of Technology and Washington DC-based company Sigma Space.
Factory fumes and smog from trafficcrammed roads add to air pollution.