by GEOFF CUMMING
As more and more vehicles clog Auckland's main transport arteries, health officials are warning of the lethal effect of exhaust fumes unless congestion is tackled.
Their fears are fuelling calls for a major boost in public transport to reduce our reliance on private cars.
But that means reversing runaway increases in car use and fuel consumption. Aucklanders' vehicles guzzled nearly a billion litres of petrol and 400 million litres of diesel in 1998. Diesel use in particular is soaring, while overall consumption has risen 70 per cent since 1986.
And the city's public transport fleet hardly offers a green alternative - its ageing diesel buses and trains are themselves sources of air and noise pollution.
The atmospheric nasties causing most concern are carbon monoxide, nitrogen oxides and fine dust (particulates). At times their levels exceed safe limits set by the World Health Organisation.
While not yet a threat to the general population, they are a danger to vulnerable groups such as those with heart and respiratory diseases - and Auckland has one of the world's highest rates of asthma.
Established blackspots include Queen St, Hobson St, Khyber Pass Rd and heavily congested parts of the Southern Motorway. Auckland medical officer of health Dr Virginia Hope says limits are being breached more often and in new areas.
"People with asthma or heart disease who stay in certain areas for long enough are likely to see an effect."
Auckland Regional Council air pollution scientist Kevin Mahon says increasing congestion will compound the problem, because vehicles cough out more pollutants while idling in traffic.
Fumes are worst at congested intersections, motorway interchanges and in concrete canyons such as Queen St, where foul air can be trapped.
"With projected population growth we can see that the vehicle fleet is going to nearly double in the next 50 years," says Mr Mahon. "Unless we do something about alternatives, congestion is going to spread, so we will get more areas where health guidelines are exceeded."
At the notorious Khyber Pass Rd monitoring site near two secondary schools (Auckland Grammar and St Peter's College), carbon monoxide levels exceeded the WHO limit for eight hours' exposure on nine occasions in 1998. Mr Mahon says the one-hour level is also being breached, and he cautions against asthmatic children waiting long periods for a bus on the busy thoroughfare.
Levels of nitrogen dioxide topped the one-hour safe limit seven times in 1998 and exceeded the annual average guideline. Dominion Rd and Penrose monitoring sites have also recorded breaches of the limits for nitric oxide and nitrogen dioxide.
Carbon monoxide safe levels have been breached in Queen St, Dominion Rd, Hobson St and in parts of East Tamaki.
Levels of smog-causing fine dust (particulates) breach health guidelines near busy roads and in residential areas. While domestic fires are the main villain, diesel is another source of particulates and its use has soared with the popularity of four-wheel-drives and Japanese imports.
Diesel also produces high levels of sulphur dioxide and has been linked to thousands of cancers in the United States.
The ARC has anecdotal evidence of public concern at smoke discharges from diesel buses, vans and trucks. But Mr Mahon says the unseen emissions from petrol vehicles are just as dangerous.
Associate Professor Robert Raine, of the Auckland University energy and fuels research unit, says the pollution levels are disturbing.
"An exceedance of even 0.1 per cent has to be a concern. These levels are there as a maximum - and in a country we like to think of as clean and green."
Vehicles also add significantly to global warming through greenhouse gas emissions, particularly carbon dioxide.
The price of air pollution in Auckland, including social costs and environmental damage, has been estimated at $355 million - a cost which some argue should be sheeted home to the motorist.
Toxins traced to motor vehicles have also entered the food chain - Auckland University researchers in 1997 found heavy metals and other contaminants in shellfish growing near the Southern Motorway.
But experts say reducing pollution is not simply a matter of persuading Aucklanders to swap cars for public transport.
Transit New Zealand has used vehicle emission research to argue for extending motorways to improve traffic flows.
An emissions modelling package developed for the Ministry of Transport showed that realignment work would significantly reduce toxins affecting housing near the end of the Northwestern Motorway.
Ian Moncrieff, a consultant who worked on the package, says there is no "single shot" answer to reducing emission levels, which vary with location.
"Putting more buses on the roads is not the answer unless you can reduce the number of cars. On two-lane roads, buses can delay other traffic and cause emissions to go up."
Basic road improvements and better light-phasing can improve traffic flows and reduce emission levels. The ministry says its modelling package will help local bodies to decide the best approach in any given situation.
Jenny Dickinson, the ministry's assistant safety and environment manager, says modernisation of our vehicle fleet will reduce emissions over time.
Most new vehicles entering the country now have catalytic converters fitted to reduce emitted toxins. The ministry is working on a law change to ensure that all vehicles entering New Zealand comply with emission standards in force at the time of manufacture in their country of origin.
The Government also plans to strengthen police powers to get smoky vehicles off the roads. And a discussion paper on new air-quality guidelines, based on the WHO levels, will be released shortly by the Ministry for the Environment.
But Professor Raine and other experts argue that accelerating congestion will overtake tougher regulations and modernisation of the vehicle fleet.
"Growth in the roading network is not going to keep pace with the growth in the fleet, and only eight to 10 per cent of vehicles a year are being replaced with newer models," he says.
"It comes back to better public transport."
Yet, as Professor Raine points out, Auckland's existing public transport fleet is not an environmentally sound alternative. He is scathing about noisy diesel buses, not to mention Tranz Metro's ugly diesel railcars.
"Pollution even from public transport is a bit of a disgrace. They're hardly going to encourage people to hop on a bus if it's making a thundering noise.
"Money needs to be spent on improving the situation."
In Christchurch, which has the country's poorest air, emission-free electric buses (remember the Auckland trolley buses?) are on trial to reduce pollution from the diesel bus fleet.
Mr Mahon says the ARC is watching the trial with interest.
Public transport, he says, will not end air pollution, but it will help to reverse an unhealthy trend.
Something's in the air
Toxins from vehicle exhausts causing most concern include:
Carbon monoxide
