Centre and auto manufacturers have argued for a new source apportionment study to conclude the pollution contribution from large diesel cars. The application they filed questioned why diesel vehicles are being segregated when petrol vehicles also cause CO 2 emissions.

"We will not order any coercive measures today," the NGT bench said, directing state governments to file affidavits within three weeks with details of two most polluted cities in their states, total number of vehicles with break-up of diesel, petrol, heavy and light including two wheelers and three wheelers, details of industrial or mining led pollution if there is, population in the cities, and whether the states have any vehicle dismantling unit in the states.

Some states like Jharkhand, Punjab and Uttar Pradesh that had come prepared with details, mentioned Dhanbad, Amritsar and Hapur respectively to be their most polluted cities.

The ministry of heavy industries and public enterprises represented by additional solicitor general (ASG) - Pinky Anand and advocate BalenduShekhar, the society of auto-mobile manufacturers (SIAM) represented by Abhishek Singhvi on Tuesday argued that diesel was not the only source of air pollution, and that a source apportionment study needs to be done first.

Neither mentioned IIT Kanpur's source apportionment study that was made public earlier this year. "The government has a plan for air pollution which has short, medium, and long term goals. Without a scientific source apportionment study it's difficult to assess," Anand said, adding that a ban of diesel vehicles will severely impact the centre's Make in India campaign and FDI.

Their application states: "The automotive industry is the largest constituent of the manufacturing sector in the country's economy, contributing to more than 47% of the manufacturing GDP of the country. It employs over 30 million persons with a cumulative investment of Rs 143,000 crores and production of Rs 556,555 crores." It adds that a "scrapping policy" for phasing out older vehicles will be submitted shortly to the cabinet which will enable their replacement with "fuel efficient and environment friendly" vehicles.

The application lists out many other measures the government was considering. The ministry argued in the affidavit that "CO 2 is a greenhouse gas responsible for global warming, and there is international consensus on the need to control GHG emissions. Petrol emissions are higher in CO 2, CNG is high in NO x, and diesel is high in particulate matter (PM). Thus, any perception of whether a particulate fuel may be labelled as being more polluting than the another depends on the parameter being emphasized." the application stated.

Environmentalists and the SC appointed Environment Pollution Control Authority (EPCA) have however submitted to SC that diesel emissions ought to be curbed because it has been graded as a class I carcinogen by the World Health Organisation (WHO) and that the norms allow them to emit more particulate matter and NO x than petrol vehicles.

Recent tests on diesel vehicles across models by government agencies in the UK, France and Germany had also revealed that on road emissions of oxides of nitrogen (NO x) in Euro V and Euro VI diesel vehicles were far higher than prescribed standards.

The SC in December banned the registration of diesel luxury cars (more than 2000 cc) in Delhi.

Measures to control pollution suggested by Centre in its affidavit to NGT on Tuesday:

Short term measures (3 to 6 months)

A note on scrapping policy will be submitted to the Cabinet in the next three months for scrapping of old vehicles which are not meeting the emission norms.

Pollution Under Control (PUC) process reforms through checking of PUC centers and undertaking of enforcement drive to ensure 100% coverage of all vehicles plying on road

Continue diversion of non-Delhi bound commercial vehicles

Increase blending of bio-diesel in diesel

Notify regulatory standard of end of life of vehicles

E-tolling has been started on national highways, will be fully implemented in six months

Medium term measures (6 month to 2 years)

Complete eastern and western peripheral expressways

Strengthen public transport by way of fleet, use of IT in public transport

Introduce electric and hybrid vehicles in the public transportation and government fleet.

Long term measure (more than 2 years)

Implement Delhi decongestion plan. (Linking of radial roads with EPE and WPE)

Promote vehicles, which run on ethanol, bio diesel especially in public transportation. Accordingly Norms have already been notified.

Convert existing vehicles which run on older BS Norms to electric and hybrid vehicles by retrofitting.

Introduce 6-7 million electric and hybrid vehicles on road by 2020 through National Mission on Electric Mobility