In a letter to the Environment Secretary, Mr. Hussain said though it was heartening to see that ambient air quality had improved in the past few days, pollution-control measures taken during the severe smog days earlier this month should continue the entire season.

“Various meteorological forecasts and reports indicate that this phase is temporary and ambient air quality may once again worsen in the coming weeks,” said Mr. Hussain. He said road-side spraying of water to reduce dust suspension, mechanised sweeping and crackdown on polluting and overloaded vehicles should continue. Burning of waste as well as biomass for heat by security guards at night should not be allowed, he added.

Stringent measures such as ban on construction activities and entry of trucks have been rolled back following the improvement in air quality.

However, the National Green Tribunal has ordered fines of ₹50,000 and ₹5,000 for violation of dust-control measures at construction sites and burning of waste, respectively.