New Delhi, Dec 14: The increasing number of diesel cars are playing havoc with the air of the capital and other major cities, as even Euro III diesel vehicles emit 7.5 times more toxic particulate matter (PM) than petrol cars.
The enormous difference in the actual emission levels of Euro III (Bharat Stage III) diesel and petrol cars has been highlighted in an analysis carried out by Delhi-based Centre for Science and Environment (CSE) on the data released by the Pune-based Automotive Research Association of India.
As per the study, one diesel car is equal to adding 7.5 petrol cars to the car fleet in terms of PM emissions and three petrol cars in terms of NOx emissions.
''This clearly reflects the flawed emission standards that allow diesel cars to emit more NOx and PM compared to petrol cars.
Total air toxics from a diesel car that are very harmful and carcinogenic are seven times higher than petrol cars,'' the CSE said.
"Delhi's pollution battle can turn very difficult if dieselisation of the car fleet is not checked right now," says Anumita Roychowdhury, head of CSE's Right to Clean Air Campaign.
Diesel cars are nearly 30 per cent of the new car sales and are expected to be 50 per cent by 2010. Other Indian cities are also at serious risk. Already, more than half of Indian cities have critical levels of particulates.
Saying that it was a myth that the diesel car technology, that was available currently in India, was clean, the CSE called for immediate policy intervention.
It has demanded introduction of 'clean' diesel technology that runs on diesel fuel with sulphur content less than 10 ppm and is fitted with advanced emissions control devices like particulate traps. Otherwise, get off the diesel route.
It also demands removal of price incentive for diesel cars. A flawed fuel tax policy that keeps diesel taxes nearly 40 per cent lower than petrol is inciting dieselisation.
The NGO pointed out that in Brazil, cars were not allowed to run on diesel because of lower taxes on diesel fuel, and in Denmark diesel cars were taxed higher to offset the lower prices of diesel fuel. Therefore, levy higher taxes on diesel fuels and cars to prevent use of cheap and poorer quality of diesel in cars, and persuade people to consider cleaner alternatives.
The CSE said that diesel-related emissions were already very high in Delhi's air. It is a matter of serious concern that the monthly average levels of tiny particulates, smaller than 2.5-micron size (PM2.5), that go deep inside lungs, have hit a dizzying height of 245 microgram per cubic metre in Delhi.
The daily peaks can be at more than 600 microgram per cubic metre.
The World Health Organisation (WHO)has said that there is no safe level for PM. Studies in the US show that even at very low concentrations and with an increase of only 10 microgram per cubic metre, PM2.5 is associated with significant increases in health risks like asthma, lung diseases, chronic bronchitis and heart damage. Long-term exposure can cause lung cancer.
What's worse, in Delhi, levels of nitrogen dioxides (NO2) are also spiraling and daily levels have hit 300 microgram per cubic metre.
Both these pollutants dominate diesel exhaust emissions.
New study and more clinching evidence prove immediate harmful effects of diesel emissions. Even as international regulatory and scientific agencies believe that diesel exhaust is of sufficient concern to merit action, more stunning evidences have come last week from a study in England.
The study 'Respiratory Effects of Exposure to Diesel Traffic in Persons with Asthma' (The New England Journal of Medicine, December 6, 2007) has specifically investigated the link between asthma and diesel exhaust. It says that diesel exhaust fumes on polluted streets have a measurable effect on people with asthma.
In the study, about 60 participants -- all asthma cases -- walked for two hours along Oxford Street in London where diesel vehicles dominate, and, on a separate occasion, through Hyde Park.
Participants had significantly higher exposure to PM and NO2 on Oxford Street than in Hyde Park. Walking on Oxford Street induced reductions in lung capacity accompanied by increases in inflammation and airway acidification.
''This is scary, when added to the evidence of acute cancer-causing potential of diesel pollutants. The International Agency for Research of Cancer (IARC), WHO, United States Environmental Protection Agency, etc have all classified diesel emissions as carcinogenic,'' the CSE said.
The CSE had commended the Delhi government's ''proactive'' move towards clearing the air in the national capital region.
The Delhi government has recently demanded -- from the Union government -- cleaner fuels and vehicle standards for the NCR, or restraints on diesel car growth in the region.