On paper, it looked like a simple decision. But in practice, the implementation of a new emissions standard slashing pollution levels from diesel vehicles has left many buyers and dealers in the lurch.

According to the Motor Traders Association (MTA), the so-called Euro IV standard, which came into effect on Oct 1 last year, has seriously disrupted business, because there are simply not enough compliant models available.

The association says it supports the Euro IV initiative, but the implementation date was imposed too early for everyone to comply in time.

Europe and Japan - where most of Singapore's vehicles come from - introduced the same standard a few years ago. Manufacturers there had until this year to switch all the vehicles they are producing to the new standard.

In Japan, any new model launched from January 2005 had to comply with the new standard, but models already in production were given until September this year to comply, 11 months later than Singapore.

Europe imposed similar deadlines to minimise disruption to car manufacturers.

Although Euro IV was announced there as far back as 2000, the cut-off date for all models to switch over was this month, three months after Singapore.

As a result, several Euro IV models were not ready by the October deadline, and many still are not ready.

MTA president Chia Yong Sian said: "As Singapore is a comparatively small market (accounting for less than 0.3 per cent of worldwide sales), manufacturers will not allow their global production and inventory strategies to be dictated by it."

The National Environment Agency (NEA), which stood firm despite several appeals for an extension, implemented the early deadline because the amount of ultra-fine soot in the air here exceeds the United States Environmental Protection Agency's recommended safe level by 40 per cent.

Diesel vehicles are responsible for an estimated 50 per cent of that amount.

Known as PM2.5 - particulate matter 2.5 microns or smaller - this fine soot is a health hazard.

"High levels of PM2.5 pose health risks, as the fine particulates can penetrate deeper into the respiratory system, causing asthma and various respiratory diseases," the NEA said.

Euro IV engines emit around 90 per cent less PM2.5 than Euro II engines, which drive the majority of diesel vehicles here.

Though the NEA expects the new standard to help Singapore achieve safe PM2.5 levels by 2014, motor traders say the hurry to implement it could be counter-productive.

With the recent crash in the commercial vehicle COE premium to $1, the fee to renew certificates of entitlement on existing goods vehicles on the road has also plunged. This means large numbers of owners might extend the lives of their Euro II vehicles instead of buying new Euro IV ones, defeating the objective of early implementation.

Already, being earlier than Japan has come at a price. Before last October, commercial vehicle buyers in Singapore had a choice of 160 models across 40 brands. Between October and last month, Land Transport Authority figures showed new registrations covered only 33 models from 11 makes.

New registrations have also plunged, partly because of a rush to register new vehicles before Oct 1.

In November, six buses and 390 goods vehicles were put on the road, compared with 471 buses and 2,873 goods vehicles in September.

The bulk of models that did not make the cut-off were from Mitsubishi, Nissan, Daihatsu and Isuzu. Replacements for most makes will not start arriving until March, with most taking until the end of the year.

The NEA says the supply disruption is 'temporary' and insists that that a complete range of commercial vehicles is available, although not across every brand.

But some buyers are unwilling to change to other brands.

Fleet owners like scrap dealer Steven Goh, minibus operator Leong Kong Yew and furniture maker Chua Lian Choon told The Straits Times they want to replace their ageing Nissan trucks and buses, but the new models are not available here yet.

Toyota was the only Japanese maker able to supply a full range of Euro IV commercial vehicles in time, but it will take another year or so to get a substitute for its Toyota Crown cab to the Singapore market.

NEA chief executive Lee Yuen Hee says the agency was aware that Singapore was implementing the standard earlier than Japan and Europe, but stuck to the deadline because "we did not get a strong and clear indication that the manufacturers could not meet it".

Since the deadline was announced in early 2004, the motor industry has been appealing for a delay, even roping in the assistance of the Japan Automobile Manufacturers Association.

Even so, dealers did try their best. Mitsubishi considered sourcing vehicles in Britain and Toyota looked at a European model called the Avensis as a possible taxi, but both plans fell through.

The industry was more than a little surprised when the move to Euro IV was announced. Singapore's original plan was to ease into the stringent standard by adopting Euro III first.

Next to Hong Kong, which went Euro IV in January last year, Singapore is the only country in Asia that has embraced Euro IV. The Straits Times understands supplies of some Japanese makes in Hong Kong have also been disrupted because of the early implementation.

The Government was of the view that going the Euro III-Euro IV route would be too slow in clearing the air. Still, observers wonder if Euro IV could have been introduced more painlessly for all.

"The implementation could have been less harsh," said the distributor of a European brand with a ready supply of Euro IV models. "Even in Europe, consumers and businesses are given several years to phase into a new emission standard. Those who can do so earlier are given attractive tax breaks."

He said the five percentage point cut in tax extended to early adopters here for commercial vehicles was 'not meaningful'.

Mr A.C. Neo, marketing director of Nissan agent Tan Chong, said his company will lose sales of more than 3,000 vehicles because Nissan would not have a full range of Euro IV models until next year.

Mitsubishi agent Goldbell Engineering stands to lose about 2,000 units in sales and has taken its appeal up with the Ministry of the Environment and Water Resources.

And though Toyota agent Borneo Motors saw van and truck sales rise 40 per cent last month, its taxi sales have ground to a halt.

Managing director Mark Choong said: "Even if the implementation date was pushed back, we would have been better off because of the taxi business."

The loss of its taxi business is expected to cost Borneo Motors - part of the London-listed Inchcape plc group - revenue of about $100 million. At a conservative 10 per cent margin, that works out to be $10 million in earnings.

Ultimately, the NEA said, the cost to the car industry had to be "weighed against the more fundamental environmental and health considerations".

Nevertheless, when the time comes to adopt Euro V, Mr Lee admitted the agency will have learnt some valuable lessons.