New Delhi, Dec. 20 -- The air quality index in Delhi-NCR continued to deteriorate on Saturday, 20 December, as the national capital choked on poor air quality and toxic smog, with the Central Pollution Control Board (CPCB) recording an Air Quality Index above the 400-mark.

The region witnessed a thick layer of toxic smog, significantly reducing visibility, impacting flight operations, and affecting the overall quality of life for residents of Delhi-NCR.

Delhi's AQI stood at 410 at around 9 pm, reaching the 'severe' category, according to CPCB data. In certain regions in the national capital, the AQI stood at the 'very poor' level.

An AQI between 0 and 50 is considered 'good', 51 to 100 'satisfactory', 101 to 200 'moderate', 201 to 300 ...