India Gate engulfed in a layer of smog, in New Delhi. The national capital woke up to a layer of smog on Diwali morning with the city's air quality index (AQI) slipping into the 'very poor' category, as it crossed the 300-mark.

High-rise buildings engulfed in a layer of smog, in New Delhi.

Pedestrians cross a footover bridge amid hazy conditions in Delhi-NCR, in New Delhi. Smog blanketed Delhi-NCR on Diwali morning, marking a noticeable decline in air quality.

Akshardham Temple engulfed in a layer of smog, in New Delhi.

A metro train runs during a smoggy morning, in New Delhi.

A man wears a face mask as air quality deteriorates in Delhi-NCR, with India Gate seen in the background, in New Delhi. Smog blanketed Delhi-NCR on Diwali morning, marking a noticeable decline in air quality.