New Delhi, Dec. 22 -- As wind speeds picked up briefly, Delhi's air quality improved marginally on Sunday, bringing it down from the 'severe' down to the 'very poor'.

Delhi's 24-hour average air quality index (AQI) was 377 at 4 pm on Sunday, when the Central Pollution Control Board (CPCB) issues its daily national bulletin. It was 398 (very poor) at 4 pm on Saturday, with the AQI crossing 400 by the evening as a thick layer of fog - combined with high polluted created smog in the region.

Experts attributed this to a marginal increase in wind speed. "Winds, though not picking up significantly, were consistent at around 5-7 km/hr on Sunday morning which helped reduce fog intensity and also created some dispersion," said Mahesh Palawat, vi...