The levy will be collected by the existing toll booths at the 127 entry points to Delhi from Haryana, Uttar Pradesh and Rajasthan.

This will be the second most significant anti-pollution intervention on the part of the apex court to help improve the ambient air quality in the national capital after 1998, when it had directed conversion of the entire city transport fleet — buses, taxis, auto-rickshaws and trucks — to switch to cleaner CNG fuel.

With SC engaging with Delhi's critically high air pollution levels, seen to pose serious health concerns, amicus curiae Harish Salve presented the outline of the levy proposal to a bench of Chief Justice H L Dattu and Justices Arun Mishra and Adarsh K Goel. The proposal was arrived at after Salve held discussions with solicitor general Ranjit Kumar on behalf of the Centre and senior advocate Dushyant Dave for Delhi government.

The lawyers and the bench agreed to adopt the additional pollution levy of Rs 1,300 on big trucks and Rs 700 on LCVs, as decided by the National Green Tribunal. The bench clarified it would pass the order on suggested lines and direct its strict enforcement for four months. "We will examine its effect on the pollution front after four months and hear all parties for further improvement and fine-tuning of the order if need be," it said.

The court intends to slap the anti-pollution levy on trucks using diesel as fuel and not on those using cleaner CNG. The levy would be payable by all diesel-run trucks whether they use Delhi roads as transit routes or enter the capital to deliver goods.

The court said it would also exempt passenger buses and mini vans, emergency vehicles and those carrying essential commodities - food grains, fruits, milk, vegetables, all kinds of food stuffs and oil tankers - from the pollution levy.

The bench was worried that collection of additional levy could result in traffic snarls caused by haphazardly queued trucks at the levy collection booths. But, Salve said: "facility of collection of toll exists on all entry points into the city. Therefore, collection of environment compensation charge will not entail further delay or inconvenience or disturbance to other traffic."

The toll collecting contractors would collect the additional levy and hand over to the Delhi government on a weekly basis, preferably every Friday. "The Delhi government may use the money for augmenting public transport and improving the roads, particularly for most vulnerable users - cyclists and pedestrians," he said.

The court also accepted the suggestion that Haryana, UP and Rajasthan governments must prominently advertise for the benefit of truckers warning them of the additional levy to be paid by them if they entered Delhi and also inform them about the alternative routes to bypass Delhi.

Salve pitched for installation of radio frequency identification (RFID) mechanism at every entry point to prevent contractor from allowing entry to trucks without accounting for them on records submitted to the municipal authorities.

"This is why the MCD record shows entry of only 22,000 odd trucks every night into Delhi though independent sources put it at over 38,000. Under the contracts with the MCD, the private toll collectors are obliged to put in place RFID systems at their own cost, but it has not yet been done. A direction is necessary that RFID facility be installed across all 127-entry points," he said.

"This RFID system should be installed by November 2015 at the nine main entry points, from where 75% of the commercial traffic enters Delhi. All remaining entry points should be covered with RFID facility by January 2016. If this is not done by the stipulated deadline, then the contractors would be treated as being in breach of their obligation," Salve said.

In 1998, three years after the lawyer had filed his case and as a direct result of it, the Supreme Court published a directive that specified the date of April 2001 as deadline to replace or convert all busses, three-wheelers and taxis to CNG. In addition, the directive specified that an infrastructure of 70 CNG refuelling stations had to be made available, and asked for financial incentives for the conversion of vehicle fleets.