Lack of options

Lack of options

Recent studies show that neither using clean diesel fuel nor improving the quality of the engine help in solving the threat of particulate matter in diesel emissions. So banning the manufacture of diesel cars may be the only option to counter the threats posed by particulate matter.

Fuel quality A recent study conducted in California comparing emissions from a new diesel engine running on older diesel fuel, and on a reformulated diesel fuel, revealed that the newer fuel only slightly reduced emissions of nox and particulates.

A report in the leading monthly review of worldwide developments in automobile technology, Automotive Environment Analyst, published in February 1999, goes on to state, "Contrary to most current thinking, switching to ultra-low sulphur fuel, so-called 'city-diesel', might affect exhaust emissions in such a way as to worsen, rather than ease respiratory health problems." The conclusion was put forward at an Institution of Mechanical Engineers' seminar held recently in London on "Diesel Engines -- Particulate Control" by Omar Hayat, managing director of ChemEcol (uk) Ltd, who conducted studies on diesel engines.

Why does Hayat say so? He says so because he found in his studies that while the total quantity of particles went down, the number of smaller particles increased. The greater the number of particles in the emissions, the smaller is their average size and more deeply they are able to penetrate the respiratory tract.

He concluded: "On aggregate, switching from regular to ultra-low sulphur fuel reduced average particle size significantly." This shows that even improving the diesel fuel quality does not help reduce the threat to human health. The cleaner the diesel, the tinier the particulate matter, increasing its toxic potential.

Engine quality
In India, it is not just diesel quality that is inferior. Diesel engine standards to be enforced in India from 2000 are the ones applied in Europe in 1992. Automobile manufacturers' only bemoan the fact that the diesel is of a very poor quality. But the fact remains that diesel engines currently produced and proposed to be produced in India are also extremely outdated and highly polluting.

The mass emission norms to be enforced in India in June 1, 1999 are the Euro i (1992) norms. Europe moved onto Euro ii norms in 1996 and will be enforcing Euro iii norms in 2000. (see table: Indian standards vs Western standards).

Amid growing evidence that even improving emission norms for diesel vehicles and improving diesel quality will not solve the problem of toxic particulate emissions, India is going to apply Europe's 1992 standards in the year 2000, though the recent Supreme Court has order has changed this for Delhi (see article: Applying the brakes, pg 13).

European norms themselves are very poor by world standards. The strictest standards for diesel engines in the world are in California which are even more stringent than the standards prevailing in the rest of usa. us standards, in turn, are much higher than European standards. These standards are low presumably because one of the world's biggest manufacturers of diesel engines, Puegeot, is a French conglomerate (see box: Paris: What diesel can do).

The Indian automobile industry says European countries have allowed the proliferation of diesel cars, but emerging evidence shows that other countries are also beginning to re-evaluate their diesel policies (see box: A wrong notion).

But will diesel engines become cleaner in the future? If we compare the standards that are being set in Europe for the years 2000 and 2005 for diesel and petrol cars, we find that even Europe has not effectively come to grips with the problem of particulate matter and nox emissions from diesel vehicles. This is evident from the fact that the limits set for these emissions are several times higher than the levels allowed to petrol vehicles. European proposals applicable from 2000 show that even in Europe, with the best of technology, diesel vehicles will emit 3.3 times more nox than petrol vehicles. At the same time, diesel vehicles have been set a particulate matter standard of 0.05 gm/km whereas no standard has been set for petrol cars because petrol cars have very small particulate emissions. In other words, particle emissions will be 10-100 times more in diesel than petrol cars.

Moreover, diesel engine manufacturers, too, are yet to resolve the problem of lowering both nox and spm emissions from diesel engines. Changes needed in the engine to reduce nox emissions tend to increase particulate emissions and vice versa, says a 1996 World Bank study. Therefore, a manufacturer who designs diesel engines has to choose between high nox or high spm emissions.

When efforts were made to design diesel engines to reduce the total quantity of particulate matter in the exhaust, the particles became smaller and their numbers went up dramatically. According to the Scientific Review Panel of carb, despite a substantial reduction in the weight of the total particulate matter in emissions, the total number of particles emitted from a 1991 model engine was 15 to 35 times greater than the number of particles emitted from a 1988 model engine, when both the engines were operated without emission devices.

After recognising diesel as a toxic air contaminant and a carcinogen in August 1998, the California government has adopted a plan making it mandatory for petrol and diesel-powered light duty vehicles to meet tighter emission standards beginning in 2004.

Emission control devices for diesel vehicles are still not commercially viable and their effectiveness is still to be proved. To reduce particulate matter, a device called a particulate trap is needed, but they are still in the experimental stage.

The only option
Thus latest scientific evidence suggests that neither improving the diesel fuel quality nor tightening the engine quality helps in averting the acute cancer-causing potential of diesel emissions, particularly particulate matter. Thus, it is necessary to ban the registration of new diesel-driven private vehicle fleet immediately because of increasing evidence of the cancer-causing potential of diesel emissions. And this ban should stay in place till the West has found a way to control the deadly particle emissions from diesel exhaust (see diagram: Are there any options but to ban diesel cars?).

Even if the government initiates measures to set new standards for diesel cars or equalise diesel and petrol prices, these measures will take time during which manufacturers will have increased their investments and many diesel cars would have already been purchased by consumers putting at stake the lives of about 250 million urban Indians.

In the Vellore Citizens Welfare Forum versus the Union of India (1996) 5 scc 647, the Supreme Court had stressed on the importance of the "precautionary" principles and the "polluter pays" principle. To protect the environment, the "precautionary principles" should be given priority over the "polluter pays" principle. Otherwise, polluters would be free to increase pollution on payment of large sums of money.

A ban on the registration of diesel driven private vehicles fits well with the precautionary principle.

(The article is based on a monograph prepared by Anil Agarwal, director, Centre for Science and Environment, New Delhi)