Toxic killers threaten to engulf city

It's Auckland's invisible assassin. Soot particles, so tiny that five can fit on the width of a human hair, are triggering strokes and heart attacks by clogging the bloodstream.

Last year, Auckland breached national health guidelines for air safety on 40 different days - sometimes at twice the safe level of toxicity.

Ever-increasing traffic and household fires are blamed for the pollution.

Now drastic measures are being considered by local authorities to clear the air to meet a national deadline of 2013.

The Auckland Regional Council estimates 400 people die prematurely from bad air each year.

The annual health cost is a staggering $1.3 billion.

More than 250 people die from vehicle exhaust emissions alone - twice the number killed by passive smoking or road accidents.

A brown haze, which hangs on the Auckland skyline when the winds are calm, is the only visible warning sign of the growing danger.

But the fine dust unseen by the naked eye is more insidious, say air pollution experts.

Queen St, Khyber Pass, the Bell Reserve in Pakuranga and Westlake Girls High School in Takapuna were the worst hit by the invisible soot and nitrogen dioxide.

More than 4900 tonnes of pollution goes into the air each year.

This is a figure which Auckland must halve by 2013 to meet national safety guidelines.

"People see a smokey diesel truck and worry about it. But the invisible particles are the stuff that will kill you," said air quality scientist Gerda Kuschel. "The problem is 'killed by smoke' is not stamped on the death certificate."

These fine particles, or PM10, are a by-product of burnt wood, coal, petrol, diesel or backyard waste.

The suspended soot particles are so small they evade the body's naturalfilter systems - the nose and throat - and get lodged in the lungs.

Wheezing, bronchitis and asthma attacks are common side-effects but, in more serious cases, the particles enter the bloodstream and trigger heart attacks or strokes.

The ARC has strictly monitored the soot since 1999, and records show the pollution peaked at nearly double the safe level of 50mcg per cubic metre of air.

What's worse, is that the levels of PM10 and nitrogen dioxide are both tipped to breach international guidelines in the next six months.

Mostly emitted by traffic and trapped in Queen St's narrow confines by the tall buildings, nitrogen dioxide can cause lung problems, provoke or worsen asthma and lower resistance to the flu.

Auckland breached the National Environmental Standards 22 times last year - and at least 21 times each year since 1999.

More than half the particles are from vehicle exhausts, with only 8 per cent from businesses, and 41 per cent from 140,000 fires in homes.

Ms Kuschel said drastic measures must be taken if the ARC is to meet the safety benchmark in seven years' time.

A ban on all open fires and coal burning in Auckland is among the more extreme recommendations to the regional politicians.

The council may also follow the lead of two of the worst affected regions, Canterbury and Nelson, and offer poorer families loans or subsidies to replace open fires with gas or electric heaters.

A recent presentation to the ARC also suggested lobbying the Government to impose stricter emission controls on imported second-hand cars. Central government has already clamped down on smokey vehicles, with a 10-second smoke rule for cars to pass warrant of fitness likely to be enforced by the end of the year.

Even with petrol prices rising and motorists buying smaller-engined cars and driving less, the positive effects of that trend are unlikely to be seen for another 15 to 20 years.

In 2004, the Environment Ministry banned the burning of tyres and imposed 13 other rules in a bid to clear the air by the self-imposed 2013 deadline.

New wood-burners must not emit more than 1.5 grams of soot per kilogram of fuel burned.