By Ashish Mishra 

New Delhi, Jan 17 (IANS): The fortnight-long odd-even campaign aimed at battling air pollution in Delhi which ended on Friday night brought down direct emissions of pollutants from cars by 30 to 40 percent, says leading environmental NGO CSE.

"During odd-even formula, direct emission of pollutants from the cars in the city was reduced by 30 to 40 percent. It happened because of fewer vehicles plying on the road," Centre for Science and Environment's air pollution control unit programme manager Vivek Chattopadhyay told IANS.

He, however, added that mixed results were observed in the ambient pollution levels.

Under the odd-even scheme, four-wheelers with odd and even registration numbers plied in Delhi - a city where cars account for nearly a third of its nine million registered vehicles - on alternate dates.

Several categories were exempt from the scheme, including a string of VIPs, women drivers, emergency services and CNG-operated transport.

Delhi Transport Minister Gopal Rai had said on Friday that a reduction in pollution by at least 20-25 per cent was witnessed.

Chattopadhyay said the biggest benefit of the odd-even rule was the restriction on diesel cars and SUVs, which are the major source of vehicular pollution in the city.

"Before this, there was no restriction on diesel cars/SUVs, but with this odd-even rule a significant number of diesel cars could not come on the road which helped in bringing down the pollution levels."

According to Chattopadhyay, a report from the London Assembly Environment Committee, 'Driving away from diesel: Reducing air pollution from diesel vehicles', says diesel exhaust is a major contributor to air pollution when compared to petrol.

"The report says that one diesel car emits an equal amount of toxic health-damaging pollutants as emitted by 27 new petrol cars. So, it becomes necessary to put a curb on the emission of pollutants that are a health hazard," he said.

He added that though the odd-even rule reduced the direct emission of pollutants in the national capital, there was a need to explore more ways than one to curb pollution and traffic in the city.

Stressing on other ways to curb pollution in Delhi Chattopadhyay said, "Odd-even is good but the government should also increase parking charges in the city to limit the number of vehicles."

"The odd-even scheme should also be implemented in the National Capital Region because a huge number of cars come to the city from there, increasing pollution," he added.