Delhi's AQI hits a hazardous 404 with smog blanketing the city; restrictions imposed, including school closures and fines for violators.

The air quality of the national capital remained in the "severe" category on Saturday morning with the AQI settling at 407 at 9 am, according to the Sameer app that provides hourly updates of the national AQI published by the Central Pollution Control Board (CPCB).

Northern India encountered the recurring annual pre-winter event of air emergency where the Air Quality Index (AQI) readings of main pollutant PM 2.5 breached the 400-mark of “very poor” and landed the air of Delhi, Punjab and other northern cities into the “hazardous” category.

Delhi’s air quality remains ‘severe’ for the fourth consecutive day, with the national capital recording an AQI of 436 at 2pm on Saturday. An AQI score ranging between 400 and 500 is considered severe and it is said to cause serious health issues with existing diseases.

Air pollution choking New Delhi has ground outdoor work to a halt and disrupted air travel in the Indian capital.

After reaching a peak, Delhi’s AQI has remained in the ‘severe’ category for the fourth day in a row. Covered in a thick blanket of fog and pollution, the poor visibility has even caused many school to remain closed for the past few days.

The GRAP 3 curbs in Delhi include ban on demolition and construction activities, and entry of certain vehicles inside Delhi-NCR, among other curbs, to prevent further deterioration of air quality.