The supreme court today banned the registration of diesel SUVs and cars above 2000cc in the national capital till March 31. The court also said the decision will not affect the common man.  Around 23 per cent of the cars registered in Delhi are diesel. Diesel cars can legally emit 7.5 times more particulate matter than the petrol versions and produce more toxic nitrogen dioxide.

On Tuesday, the court had agreed to ban the entry of trucks registered before 2005 in the national capital region and increase the green tax for trucks entering the national capital.

On the Delhi government's plan to allow cars with odd and even registration numbers on alternate days from January 1 to check pollution, the court said it wasn't sure if it would help. "You can implement it if it is going to help.  We haven't stopped you."

The court had asked the state and central government to come up with a solution to clean Delhi's air. "You formulate the norms, prescribe the regime. Why don't you do it?  You take the credit for cleaning Delhi. Why do you let the opportunity go?" it said.

The court also indicated to the Delhi government, MCD and toll contractors that it would double the environment compensation charge from the existing Rs 700 to Rs 1,400 for light vehicles and from Rs 1, 300 to Rs 2,600 for two-axle trucks, three-axle trucks and four-axle trucks that enter Delhi and spew poisonous fumes.

Though the toll contractors and MCD said the present charges have resulted in 30 per cent decrease in the entry of non-destined trucks to Delhi, the judges were of the view that the fine would be a "proper deterrent" only if it was doubled.

The bench said the government shall use the money to improve the environment, augment public transport, improve roads and make extra facilities for pedestrians and cyclists as was mentioned in its earlier order.

"Trucks take alternate routes when entering Delhi just to save toll tax. In the process, pollution caused by such traffic inflicts heavy cost on the health of the residents of Delhi. If you are not destined for Delhi, then don't come. If you come, be ready to pay the heavy tax", the bench said.

The court was acting on detailed recommendations submitted by amicus curiae (senior advocate assisting the court on an issue) Harish Salve and NGO Centre for Science and Environment represented by its Director General Sunita Narain. The court was also hearing a PIL filed by Arvind Gupta, an economist who sought complete ban on diesel vehicles in Delhi.

In his petition, Gupta said: "The data available from WHO shows that Indian cities are almost 10 times more polluted than the other cities of the world, which is a serious infraction of the fundamental rights of the citizens of India. The WHO estimates that more than two million people die every year from breathing in tiny particles present indoors and outdoors due to air pollution.

PM10 particles, (particles of 10 micrometers or less) can penetrate into the lungs and may enter the bloodstream. They can cause heart disease, lung cancer, asthma, and acute lower respiratory infections."