E-buses would help improve Auckland’s air quality

A newly released report on Auckland’s transport emissions and air quality during the COVID-19 lockdown shows continuing use of buses and trucks meant some pollution didn’t decline that much.

University of Auckland researchers recorded levels of the five main pollutants – fine and coarse particulate (PM2.5 and PM10), black carbon (BC), ozone (O3) and nitrogen dioxide (NO2).

Associate professor Jenny Salmond and doctoral candidate Hamesh Patel compiled readings from central Auckland at Queen St and Customs St, suburban Henderson and rural Patumahoe.

They also compared meteorological conditions during the month to past years and found wind levels to be similar, although rainfall was historically low for Auckland, the NZ Herald

reports.

During alert level 4, light vehicle traffic volume declined an average of 80% daily compared to the previous year.

The number of heavy vehicles (diesel buses and trucks) fell 60%, but NO2 levels dropped less than most, especially in Auckland central, as buses kept running and trucks were still accessing the Ports of Auckland.

Overall, the researchers found a marked reduction in recorded levels of ambient air pollution during lockdown.

NO2 levels, mostly from the combustion of fossil fuels from motor vehicles, fell by 34.1% in central Auckland, 56.9% at Henderson and 35.6% at Patumahoe.

Salmond says this shows it matters which type of vehicles are taken off the roads.

“Although we reduced traffic by up to 80%, pollution wasn’t cut by the same amount and that’s because buses and trucks account for a higher proportion of NO2 emissions,” she says.

“This is important when make decisions about how to manage air quality in urban areas. If lockdown showed us one thing, it was that we can make significant improvements in air quality by reducing traffic flows.

“But these results suggest that gains in air quality can also be made by opting for electric buses and lower-emission buses and trucks.”

Patel says the research also highlights a lack of detail in previous emissions inventories, with some pollutant and emissions sources potentially misrepresented or under-reported.

“Increased monitoring of the ambient air is therefore crucial in improving our knowledge and understanding and so regulators can make better informed decisions to provide safer and healthier air for us all to breathe.”

Auckland and Wellington have both begun introducing electric buses, the latest in Auckland including the scheduled arrival of e-buses on Waiheke Island in November.

Electric and lower emission trucks are also increasing in New Zealand.