Busy Rd Breaches Air Quality

Since March this year, the regional council has been measuring the amount of nitrogen dioxide (NO₂) in the air at the intersection of Te Rapa Road and Avalon Drive.

The national environmental standard is breached when in one hour average NO₂ levels exceed 200 micrograms per cubic metre (μg/m³) of air 10 or more times in a 12 month period.

Between March an1 d  May 23 NO₂ levels exceeded 200 μg/m³ more than 50 times. At its highest, levels reached 556 μg/m³ between 7am and 8am on March 30.

There have been no further breaches since May 20 but this is the first we have heard about it.

Council air quality scientist Dr Nick Kim said analysis of the results has found a possible link with road works in the vicinity over summer and autumn.

“Until late May, there were more heavy trucks than usual travelling through the Te Rapa Road and Avalon Drive intersection, and these would have added to the already high base-load.

“The last exceedances coincide with the winding down of roading works for the winter, and there have been no further breaches in more than five weeks of ongoing monitoring,” Dr Kim said.

“The majority of exceedances occurred on weekdays during the morning peak and when there was little wind to disperse emissions.

“Almost all nitrogen dioxide near busy intersections like this one comes from motor vehicles, and especially from diesel vehicles. The greatest amounts of NO₂ are produced when engines are under load, such as pulling away from traffic lights, so NO₂ levels tend to be higher on busy roads that have a lot of heavy vehicles.

“A large heavy vehicle such as a truck can emit around 10 times more NO₂ than a petrol car. Even a small diesel car can emit four times more NO₂ than a petrol-run car.”

Dr Kim said people are exposed to NO₂ by breathing in air. Previous research by the former Auckland Regional Council showed that NO₂ contributions from a motorway can remain elevated up to at least 300 metres away from the roadside.

It can irritate eyes, nose, throat, and lungs, possibly causing coughing, shortness of breath, tiredness, and nausea.

The national environmental standard requires regional councils to monitor the air in cases where national standards are likely to be breached, and undertake this monitoring in the part of an airshed where exceedances are greatest or most frequent.

Waikato Regional Council believes that in the Hamilton airshed, exceedances of the national environmental standard for NO₂ are the greatest and most frequent at the Te Rapa Road and Avalon Drive intersection. Monitoring will continue until the exceedances no longer occur.

Hamilton's air polluted roads

Policy and transport group manager Vaughan Payne said the Te Rapa and Ngaruawahia sections of the Waikato Expressway, due for completion in 2013/14, are expected to ease congestion in northern Hamilton.

“The council’s Regional Land Transport Strategy supports construction of nationally and regionally significant traffic corridors, such as these two sections of the Expressway, which will channel long distance vehicles off local roads and onto major arterial roads.

“Although this will continue to be a busy intersection, the completion of the Expressway sections are likely to result in a reduction in NO₂ emissions,” Mr Payne said.

The council will continue to notify the public of any further breaches of NO₂ at this site on a monthly basis.