New Delhi: The Supreme Court will on Monday pass an order imposing an anti-pollution cess on commercial vehicles entering the national capital, which the World Health Organization (WHO) found last year has the dirtiest air in the world.

The levy, which has been proposed as a disincentive for polluting vehicles entering the city, will be applicable for an initial four months to judge how it is implemented, a three-judge bench comprising Chief Justice H.L. Dattu and justices Arun Mishra and A.K. Goel said on Friday. The bench will pass a formal order on Monday.

The Supreme Court approved, in principle, an anti-pollution charge of Rs.700 on light commercial vehicles (LCVs) and Rs.1,300 on trucks entering Delhi.

Amicus curiae (friend of the court) Harish Salve told the court on Friday that the amounts had been agreed upon by the Delhi government and the Union environment ministry. On Thursday, the court had asked Salve, Delhi government lawyer Dushyant Dave and solicitor general Ranjit Kumar to make suggestions on the implementation of the levy.

“This should be welcomed. There are comparable examples of environmental tax and eco-development charges that are imposed by local authorities in ecologically sensitive areas such as Nilgiris, Mussoorie, etc. But levying such a charge on the scale of a place like Delhi is certainly a first of its kind,” said Sanjay Upadhyay, managing partner at environmental law firm Enviro Legal Defence Firm.

The court’s decision follows increasing concern over pollution caused by fuel-guzzling vehicles in Delhi, which a WHO study of 1,600 cities, released in May 2014, ranked as the world’s most polluted. In fact, 13 of the 20 cities with the dirtiest air were Indian. New Delhi was followed by Patna, Gwalior and Raipur in the top four spots.

New Delhi had an annual average of 153 micrograms of small particulates, known as PM 2.5, per cubic metre, more than double the 60 micrograms considered to be the safe limit.

Air pollution killed about seven million people in 2012, making it the world’s single biggest environmental health risk, according to WHO.

“This is a major victory for the fight against deadly air pollution. The issue of severe and dangerous air pollution in Delhi has been acknowledged and recognized by the Supreme Court,” said Sunita Narain, director general of the Centre for Science and Environment (CSE).

“We would like to thank the Supreme Court for the decision, and amicus curiae Harish Salve who filed an application in the court, seeking immediate measures before winter sets in,” she said, also congratulating the central and Delhi governments for agreeing to and supporting this decision.

CSE has estimated that 38,588 commercial vehicles enter the national capital through nine entry points every day. That’s far in excess of a Municipal Corporation of Delhi estimate, which put the number at 22,628. Salve said that while commercial vehicles such as trucks have alternative routes, they prefer going through Delhi to avoid toll payments.

Salve brought up the issue of increased air pollution in the winter months, when it worsens because the cold air traps pollutants. In the November-January period, PM 2.5 emissions have ranged between 150 and 270 micrograms per cubic metre in the past four years.

The Delhi government would be the nodal agency overseeing the implementation of levying and collecting the pollution cess. Governments in the neighbouring states of Uttar Pradesh, Haryana and Rajasthan would have to cooperate with the Delhi government to ensure orderly implementation.

The Delhi government will be required to supervise the process through traffic checkpoints, where CCTV cameras will be installed.

It will take the help of the municipal authorities in the city to oversee the process and inform the court about the exact number of vehicles entering the national capital.

The money collected through the levy will be used by the Delhi government to augment transport in the city. The government will furnish accounts of receipts to the Supreme Court on a weekly basis.

Passenger buses and vehicles carrying essential goods like food, and ambulances will be exempt from the levy.

Nikita Mehta contributed to this story.