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Road dust kicked up by passing traffic can have a greater impact on Auckland’s air pollution than vehicle exhaust, new research has found.
The 13-year study found road dust was a significant source of PM₁₀ — tiny airborne particles linked to respiratory and cardiovascular problems.
Published in the Journal of the Royal Society of New Zealand, the research analysed air-quality data from Queen Street in central Auckland, Khyber Pass and Penrose.
Lead researcher Dr Mingyue Selena Sheng, from the University of Auckland Business School’s Energy Centre, said the findings showed vehicle exhaust was only part of road transport’s impact on air quality.
“Our findings show that road dust is, at times, a dominant and statistically significant contributor,” she said.
“Much of the focus has been on reducing what comes out of the tailpipe, but road dust and other non-exhaust emissions need our attention.”
Non-exhaust emissions come from worn brakes, tyres, clutches and road surfaces, as well as dust and debris kicked back into the air by traffic or wind.
Co-author and Business School economist Dr Le Wen said the number and type of vehicles on the road mattered because non-exhaust pollution was created as they moved.
Heavy vehicles made up only about 4 percent of traffic in the study, but were linked to higher PM₁₀ levels and played a disproportionate role in kicking up road dust.
The issue could become more important as electric vehicles become more common, as their batteries generally make them heavier.
“While electric vehicles offer a pathway to reducing tailpipe emissions, their environmental benefits may be offset by increased non-exhaust emissions, especially from heavier vehicle fleets,” Wen said.
“Moving to electric vehicles has important benefits, but it doesn’t make particulate pollution from road transport disappear. If we want cleaner urban air, non-exhaust emissions need to be a key part of the conversation.”
The researchers said reducing air pollution would require action on non-exhaust emissions as well as vehicle exhaust.
They suggested requiring vehicles carrying soil or other loose materials to contain their loads in urban areas, along with restrictions on when they can travel during peak periods.
