A blanket of smog engulfed Delhi-NCR as the region's air quality deteriorated to 'very poor' category. Air quality index (AQI) dropped to 339 in Anand Vihar while AQI was recorded at 293 at Akshardham. Videos showed a sprinkler vehicle also being used to tackle pollution. Centre's Commission for Air Quality Management has also activated Graded Response Action Plan's first stage.