The government said this while releasing the comparative ambient air quality figures collated by the Delhi Pollution Control Committee on November 20 and November 22.

The figures show up to 55 per cent reduction in level of nitrogen dioxide (NO2) along one of the car-free stretches. This happened at Dwarka’s Sector 3, where level of NO2 fell from 318 micrograms to 140 micrograms per cubic metre.

Near Panchsheel Apartments, PM 2.5 fell from 315 micrograms per cubic metre on November 20 to 276 on Sunday as number of cars came down owing to car-free day. The safe limit is 60 micrograms per cubic metre.

Another Dwarka locality, the Ayushman Hospital area which also fell along a car-free stretch, saw marginal decrease in levels of PM 2.5, PM10. NO2 was reduced to 85 micrograms per cubic metre from 123, a 31 per cent decrease.

The reduction of PM 2.5 and PM10 in the air were equally slight at Sector 3. It hovered around 9 per cent. The monitoring was undertaken from 8 am to 4 pm on both days.

“The air quality results on car-free stretch highlight the need of mass awareness programmes to convince the residents of the national capital to voluntarily give up the use of their personal vehicles for some days and the positive results will be there for all to see,” an official statement said.

Monitors of the Centre for Science and Environment, a green NGO, said that there was a significant difference in pollution exposure level, “as much as 50 per cent”, between Dwarka’s car-free stretch and the heavy-traffic stretch between Dhaula Kuan and Patel Chowk on Sunday.

“During the car-free event, the PM2.5 level was 335 microgramme per cubic metre (cum) in Dwarka. This was much lower than the levels observed in the heavy traffic stretch between Dhaula Kuan and Patel Chowk where PM2.5 levels were 645 microgramme per cum,” CSE said in a statement.