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[NEW DELHI] In 2016, the local government of Delhi state, experimented with allowing private cars to ply on the roads only on alternate days, according to odd or even registration numbers. The scheme attracted a lot of interest, but it was never clear if the scheme succeeded in improving air quality in Delhi.
A recent study says that the ‘odd-even’ scheme did have a positive impact. However, the gains from halving the number of private cars on the roads were offset by emissions from heavy goods vehicles that were allowed to ply during night hours, according to the study carried out by researchers from the University of Surrey and the University of Birmingham in the UK and the Indian Institute of Technology and the National Environmental Engineering and Research Centre that are based in New Delhi.  

“One way out is to use cleaner fuel and technology for all vehicles.”

Ashish Verma, Indian Institute of Science, Bangalore


The results show that cutting down air pollution requires much more planning than simply reducing the number of vehicles on the road. “Restricting the night hours during which lorries (trucks) are allowed into Delhi would help reduce pollution levels, as it would give pollutants time to disperse,” says Prashanth Kumar, lead author of the study and professor at the University of Surrey.  
“However, the issue of heavy goods vehicles is a difficult one to address since it is essential for economic activity,” says Ashish Verma, associate professor at the Indian Institute of Science, Bangalore. “One way out is to use cleaner fuel and technology for all vehicles.”
Vehicle exhaust, emissions from industries, biomass burning, and the burning of agricultural waste in the northern plains together make Delhi’s air highly polluted. The suspended particulate matter concentration in Delhi and in many other Indian towns and cities, far exceeds WHO guidelines [1].
While the use of public transport can reduce traffic congestion and air pollution, Indian cities lack a public transport system that provides end-to-end connectivity, says Ashish Verma, associate professor at the Indian Institute of Science, Bangalore. “A complementary set of policies like congestion charges, parking restrictions, priority for public transport, pedestrianisation and incentives for clean transport modes are also required,” Verma says. Kumar believes that while improving the fuel quality could pay dividends as it cut emissions at the source, “a more sustainable solution lies in strengthening public transport and introducing electric and hydrogen-fuel vehicles”.
This piece was produced by SciDev.Net’s Asia & Pacific desk.