Thanks to the Commonwealth Games in October 2010, Delhi, despite having 44 lakh (4.4 million) vehicles — more than those of Mumbai, Chennai and Kolkata put together — has shaken off the dubious tag of being the country’s most polluted city. Mumbai, which has less than half as many vehicles as Delhi, now tops the list in vehicular emissions because its roads are more congested, and there are fewer vehicles running on compressed natural gas (CNG).

These are the findings of a recent study by the New York-based Desert Research Institute.

In the last four years, the Delhi government has spent over Rs. 8,500 crore (Rs 850 million) to build flyovers and widen roads, another Rs. 7,000 crore (Rs 700 million) on the second phase of the Metro rail project and over Rs. 2,000 crore (Rs 200 million) for new ‘low floor’ CNG buses.

“Faster moving vehicles and better public transport have meant a lower emission footprint in Delhi,” said Sarath Guttikunda, associate professor at the institute, who led the study that compares vehicular emissions in 2008 across 20 big and small cities of India. 

In comparison, Mumbai’s infrastructure, despite the opening of the recent sealink between Bandra and Worli, has improved little. Both cities record a 10-12 per cent increase in the number of vehicles every year.

“Carbon dioxide (CO2) and particulate matter emission load from Mumbai buses, three-wheelers and taxis is more than four times that from similar vehicles in Delhi,” said Guttikunda.