India, Dec. 28 -- Delhi's air quality deteriorated further and was on the brink of the 'severe' category on Sunday morning. Wind speeds remained low in the region, with a thick layer of fog visible across the Indo-Gangetic plains, satellite imagery showed.

The city's average air quality index (AQI) stood at 392 (very poor) at 8am on Sunday -- marginally higher than 385 (very poor) at 4pm on Saturday. It was 332 on Friday, making a steady drop on the back of an approaching western disturbance, which has slowed down winds, while also adding moisture into the air. Another western disturbance is expected from December 30 till January 1 -- keeping similar conditions in place till the New Year.

Data from the Central Pollution Control Board (C...