PM2.5 levels were reported between 112.78 to 118.90 micrograms per cubic metre (g/m³) in Gurgaon on Sunday, while it was between 99.08 to 109.76 g/m³ on Saturday.

According to Haryana State Pollution Control Board (HSPCB) officials, a decline in wind speed and the burning of crackers during Dussehra celebrations led to an increase in the air pollution levels. "As the wind speed is declining, it is difficult for the dust particles to disperse, and they remain trapped in the lower atmosphere. It leads to a rise in the level of particulate matter. Also, firecrackers and effigy burning on Dussehra also had an impact," said a senior HSPCB official.

Experts blamed effigy burning on Dussehra, coupled with stubble burning by farmers, for the increase. "Despite Sunday being a non-working day, the city reported the highest levels of air pollution in the country. It is evident that vehicular pollution is not the only source of air pollution in the city. It is clearly a result of Dussehra celebrations. Also, stubble burning is a major contributing factor," said Niranjan Raje, former member of Environment Pollution Control Authority (EPCA).

Activists, on the other hand, held the non-compliance of construction norms responsible. "Despite tall claims, the authorities have failed to implement NGT's directions at construction sites, both private and public. There is massive air pollution in front of the MCG office itself due to construction activities," said Vivek Kamboj, a city-based environmentalist.