The air quality in New Delhi this Diwali season was the cleanest in the past three years, according to a report released by the System of Air Quality and Weather Forecasting And Research. The agency, better known as Safar, said the Supreme Court-imposed ban on the sale of firecrackers in the Delhi-National Capital Region during the festive season had, indeed, had an impact.

“The ban on crackers certainly had an impact,” Safar Project Director Gufran Beig told PTI. “The days that preceded and followed Diwali saw restraint from people. Usually, crackers are set off before and after the actual night of festivities, as well. The real impact could be seen on October 20.”

The level of emissions from fireworks dropped by around 40% during Diwali compared to that in 2016, dipping nearly 50% on October 19. However, the level of particulate matter in the air shot up a day later, dipping only 25% on October 20, as against last Diwali.

Despite lower level of emissions, the air quality in the national Capital had turned “severe” the day after Diwali, for the first time in 2017. Beig, however, clarified that a drop in emissions from a source did not necessarily mean that pollution had lessened.

“Emissions slow down local wind movement as air becomes heavy,” Beig explained. “But the air cleaned up faster this time due to warmer temperature and dry conditions.”

For its report, Safar, which monitors the air quality for the central government, studied the air quality in Delhi by looking at the sources of emissions and also factored in meteorological data, such as wind speed and satellite estimates of stubble burning emissions.

A study published by Lancet on October 20 had India topping the list of pollution-related deaths in the world. Ahead of Diwali, on October 9, the Supreme Court had banned the sale of firecrackers during the festive season in NCR till November 1.

In 2016, an alarming smog after Diwali in Delhi-NCR had forced schools to remain closed for three days and the National Green Tribunal to declare an environmental emergency in Delhi, Haryana, Punjab, Rajasthan and Uttar Pradesh.