Major Survey Into Motorway Pollution


NIWA scientists working with Auckland and Canterbury University are researching how dangerous Auckland’s motorway pollution is.

Using a late model Ford Falcon and getting a student to live in an Otahuhu flat near the motorway, they now have data which will be analysed and a report ready by 2012.

The data gathered will be used to evaluate and improve on the air quality models which are currently used in planning major new roads, such as the Waterview Connection.

The NIWA team are also planning follow-up studies with public health researchers to apply the findings across the country to find out how the risk from living near traffic compares to other public health risks, such as damp homes and smoking.

From the Auckland experiments, they are analysing emissions from the motorway, their dispersion downwind, and the penetration of outdoor air into the indoor environment. Emissions from other sources (local roads and domestic woodburning) were monitored upwind of the motorway.

The scientists gathered their outdoor air-quality data by:

  • Designing and mounting a mobile air-quality system in a late model Ford Falcon
  • Using a quarter-century-old bike with a basket on the front containing measuring equipment
  • Positioning sampling tubes on lampposts
  • Using 3 air-quality monitoring stations,  strategically positioned within the one square kilometre study area.

NIWA designed and mounted a mobile air-quality system in a late model Ford Falcon.

On one side of the car there was a false window that allowed outside air to be drawn through a tube and into the car. Inside the car were two instruments: an aethomemeter and a particle counter. These instruments measured black carbon and gave a time-series chart of the particles, updated second-by-second, as they entered the instruments.

“We chose a 1 kilometre radius site in Otahuhu. It’s a flat neighbourhood which allows us to concentrate on the effects of dispersion, and it’s a very typical New Zealand layout, with small sections and low density houses – it means that we can apply our results to other locations across New Zealand,” says NIWA air quality scientist, Dr Ian Longley.

Woody Pattinson, a Canterbury University PhD student, became part of this living, breathing reality, experiment as he rented a house in the area and monitored the outdoor and indoor air quality of his surroundings.

One of the aims of this work is to find out how we might reduce the number of people exposed to health-endangering concentrations of air pollution close to motorways. International research shows that the impact of major roads is significant up to one or two hundred metres distance and possibly further.

During the measurement phase, Woody was following a rigorous daily schedule.

He started his day in the house rented for the study by making sure all the instruments are running. Then, using a bike his grandfather gave him, he conducted up to three trips a day around a grid-like area, travelling at different distances from the motorway. This allowed the instruments on his bike to gather data on the levels of pollutants from the motorway. Woody even did a late bike run each night, gathering readings of smoke from wood fires.

Woody’s quarter century old bike had a basket on the front containing his measuring equipment. The cellphone in the basket logged the GPS coordinates to record where he had been, took a photo every three seconds and recorded voice logs of what he saw as he travelled. A dust monitor logged background concentrations of wood smoke, and a condensation-particle counter logged ultra-fine particles representative of fresh vehicle emissions, especially diesels.

The basket also contained a weather-tracking instrument that recorded temperature and humidity, and a carbon monoxide sensor.

While Woody was out on his bike he checked the 30 sampling tubes. These little glass flasks with filters in them were discreetly positioned on lampposts, a couple of meters off the ground, at different distances from the motorway. They gathered information that is being used to analyse the different pollutant levels away from the motorway, specifically nitrogen dioxide. Woody changed the tubes every two weeks.

The house, like a lot of New Zealand houses, was relatively draughty and not well insulated. The indoor instruments measured the same contaminants as the outdoor air-quality monitoring stations.

Most people spend most of their time indoors, especially at night and when there is wood smoke in the area.

“The choice of three-month research period, from April to June 2010, was deliberate,” says Dr Longley. “It’s the start of the wood-burning season in winter. The scientists investigated indoor air quality and the indoor exposure of local residents to car emissions, and to wood smoke. In the early stages of the experiment we were confident that most of the contaminants were due to the motorway and the traffic. As the experiment progressed we could see more and more people lighting fires, so we could contrast the difference that had on air quality.”

There are other ways to get a draught while on the Sthn motorway

The indoor instruments gathered data every minute and at the end of every week this ‘indoor’ data was sent back to the office at NIWA in Auckland. The data could then be compared with data from outside the house.

“We were trying to map air quality, street-by-street, almost metre-by-metre. So second-by-second we can see how air quality varies across our study area. The logging system was designed, created, and built entirely by NIWA staff,” says Dr Longley.

The system is sensitive enough to record the response of individual vehicles.

An Auckland Regional Council study in 2007 showed 400 people die prematurely each year because of health effects related to air pollution, much of which came from diesel.

It said that poor air quality is responsible for more than 750 000 ‘restricted activity days’ every year. Air pollution has the greatest affect on the young and the elderly, and people with heart disease, respiratory disease, asthma and bronchitis. The associated costs for the Auckland Region are estimated to be in excess of NZ$1.3 billion per year.





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