New Delhi: As early signs of winter emerge in North India, carmakers are dreading the revival of the debate over vehicular pollution.

With the air quality this year promising to be as bad as it was in 2015, they are anticipating trouble; last year, this took the form of a several-month-long ban on the sale of diesel vehicles with engine capacity of 2000cc or above. That ban was eventually lifted and replaced by a 1% green cess. Both the ban and the cess were ordered by the Supreme Court.

Supreme Court chief justice T.S. Thakur left two questions open then. One, restrictions or a cess on sale of diesel vehicles with an engine capacity below 2000cc; two, a higher green cess for all diesel vehicles.

The court had asked senior advocate Harish Salve, who was assisting it in the case, to come up with suggestions.

“The case is very much open and the Environment Pollution Control Authority (EPCA) is formulating its recommendations," said Usman Nasim, researcher with Delhi-based Centre for Science and Environment.

Earlier this month, EPCA officials met government officials from Punjab and Haryana to initiate steps to curb the burning of crops after harvest.

“Last year, when the pollution levels were high, the court took action. We are monitoring the situation even now and will take appropriate action when required," said a government lawyer involved in the case. A hearing on the issue is likely in mid-November.

Meanwhile, auto executives are preparing for the worst. Justice Thakur is to retire in January and they fear a tough debate on pollution in November and December.

“Vehicular pollution will be high but that needs to be seen in the context of other pollutants, which need to be controlled," Vishnu Mathur, director general of auto industry lobby Society of Indian Automobile Manufacturers, or Siam, said, referring to a 15 October report in The Times of India newspaper that cited data from NASA satellites to suggest that despite a ban and dire warnings from the Delhi high court, crop fires have started raging across Punjab and northern Haryana.

In what could be further bad news for Delhi’s air quality, the data indicates the fires may have begun early this year, compared with 2015, the newspaper said in its report.

“The issue of rising PM2.5 will get sorted out as soon as you sort out Diwali, crop burning in Punjab, Haryana and other such sources of pollutants," Mathur said. His reference is to particulate matter with a diameter of 2.5 microns.

The auto industry suffered a revenue loss of Rs4,000 crore between 16 December 2015 and 13 August when a ban prevented sale of diesel vehicles with engine capacity of 2000cc or above. The ban was in response to concerns over increasing air pollution in the national capital, blamed on emissions by diesel vehicles. It was lifted after the auto makers agreed to pay a 1% green cess on such diesel vehicles. EPCA had recommended a steep pollution tax—22% of the vehicle’s cost—on private diesel cars.

Delhi was ranked the world’s most polluted city in 2014 by the World Health Organization (WHO). This year, the city moved down the WHO ranking—to the 11th worst in terms of air quality.