India, Dec. 18 -- Dense fog engulfed the national Capital on Thursday morning, with both flight and rail operations impacted as air quality deteriorated in the city again. The average air quality Index (AQI) stood at 358 at 9am on Thursday - up from a reading of 334 on Wednesday at 4pm.

The India Meteorological Department (IMD) said visibility dipped to 100 metres at both Safdarjung and Palam, between 5:30am and 6:30am but is not expected to drop further.

"At 2:30am, visibility at Safdarjung was 300 metres and it was 500 metres at Palam. Visibility continued to dip and touched 100 metres at both stations, but should increase in the coming hours again," said an IMD official.

To be sure, the IMD had forecast shallow to moderate fog in th...