According to data released by HSPCB (Haryana State Pollution Control Board), nitrogen dioxide was recorded at its lowest level of 22.87 mg/m3 (microgram per cubic metre) on Thursday from 29.77 on April 12. Carbon monoxide, on the other hand, was also recorded at its lowest level of 0.56 mg/m3 (milligram per cubic metre) on Thursday from 1.03 on April 12. The level of PM2.5, however, fluctuated over the last 10 days.

While some experts credit the odd-even scheme in Delhi with bringing down the level of pollutants in Gurgaon, HSPCB officials said increased windspeed was responsible for the phenomenon.

"The air pollution level recorded by the monitoring system of HSPCB doesn't give a clear picture of the pollution in the entire city as the system can only record pollution in a radius of 4km. However, their data itself shows a trend that concentration of pollutants in the air is going down since April 15. Even though the decrease is marginal, there is a need to learn from Delhi and replicate the model in the city too," said Dr Debjani Ghosh, an environmental engineer.

HSPCB officials, on the other hand, said the odd-even scheme could not have an immediate impact on the air quality of the city. "The windspeed has increased in the past couple of days. That helps in scattering of pollutants in the air. Also, air pollution in Gurgaon is majorly owing to dust pollution. Air pollution in Delhi, therefore, has a negligible impact on the air quality of the city," said an official of HSPCB, requesting anonymity.

NiranjanRaje, a member of the Environment Pollution (Prevention and Control) Authority (EPCA) and former director of Indian Oil Corporation, said, "We live in one of the world's most polluted cities. There is already a high concentration of pollutants in the atmosphere. I noticed that the number of vehicles in the city has come down during the odd-even scheme, which might have led to reduction in the pollutants. However, we can't directly relate it to the odd-even scheme in Delhi."