The Supreme Court asked the Delhi government on Saturday about the steps taken by it to control air pollution in the national capital and sought to know if the smog towers installed by it were working.

"The Delhi government has said it has installed smog towers. Are these working?" a bench headed by Chief Justice N V Ramana asked senior advocate Rahul Mehra, who appeared in the court on behalf of the city government.

Mehra told the bench that the smog towers are working.

"The AQI was 84 on September 30 and now it has become 474. We have increased to 390 points. It is like smoking 20 cigarettes a day even if you are a non-smoker. While this court will look into various other factors, it is probably the stubble burning. If PUSA people can look into it...", he told the bench, also comprising justices D Y Chandrachud and Surya Kant.

Mehra said he will place on record a detailed affidavit about the steps taken by the Aam Aadmi Party (AAP) government.

The top court, however, said, "Affidavits and arguments are okay but the people want that the air pollution should be reduced."

It also said it has become a fashion to blame the farmers for air pollution.

The apex court was hearing a plea filed by environmental activist Aditya Dubey and law student Aman Banka, who sought directions to provide stubble-removing machines to small and marginal farmers for free.

Delhi Chief Minister Arvind Kejriwal recently inaugurated the "country's first smog tower" at Connaught Place and said it will prove to be a milestone and many such structures can be installed in the city if the pilot project yields results.

He had said the concentration of PM2.5 had reduced from 150 micrograms per cubic metre to 100 micrograms per cubic metre and that of PM10 from 300 micrograms per cubic metre to 150 micrograms per cubic metre in the national capital since 2014 due to the efforts made in the last few years.

PM2.5 refers to fine particles that penetrate deep into the body and fuel inflammation in the lungs and the respiratory tract, leading to the risk of cardiovascular and respiratory problems, including a weak immune system.

"This is the first such smog tower in the country. It is a new technology. We have imported it from the US. The structure will suck polluted air from above and release clean air from below. It will purify 1,000 cubic metres of air per second," Kejriwal had told reporters.