A Newspaper has printed a story about cars being to blame for higher pollution levels in Auckland than in a Japanese city, without a shred of an attempt at balance.
The study, published in the journal Atmospheric Pollution Research, analysed a measure of fine particulate matter, called PM2.5, for two toxic compounds that stemmed from the burning of fuel – polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives (NPAHs).
The compounds, which could be absorbed by the lungs and into the bloodstream, have been shown to affect the respiratory, central nervous and cardiovascular system.
They were also of concern for their cancer-causing and gene-changing properties.
AUT PhD student Egide Kalisa compared PAH and NPAH levels in Auckland, and at Tapora north of the city, with those recorded at seaside Kanazawa in Japan’s Ishikawa Prefecture, and at rural Wajima nearby.
Kalisa chose to compare the sites as both had similar geographic characteristics, along with prevailing westerly winds.
Pollution levels were much higher at urban sites than the rural ones. […]
Further, his data revealed cars to be the main source of NPAHs, which were found to be at higher concentrations in Auckland, measuring 48.2 picograms per cubic metre of air (pg/m3), than in Kanazawa (33.45pg/m3).
So let’s compare some numbers that may be more useful than the fact that both cities had westerly winds.
- Kanazawa has a population of 520,000, Auckland has 1,525,000. (Data)
- Japan has car ownership of 615/1000 people, NZ has 860/1000
- Assuming these cities follow the national average and multiplying that out gives Kanazawa 320,000 cars and Auckland 1,312,000 cars, roughly 4 times as many.
With, possibly, four times as many cars the measured Auckland pollution from cars was only 1.44 times worse than Kanazawa.
And remember, Japan exports the old less efficient, more polluting, cars to New Zealand where Jap imports make up a sizeable proportion of our vehicle fleet.
