Air pollution in India's capital, New Delhi, has become so severe that some residents are struggling to commute to work.

Residents in India's northern states woke up to another day of poor air quality on Tuesday, as a layer of dense fog shrouded most of the region, and pollution in the capital Delhi remained severe.

Toxic smog engulfed much of northern India on Monday and pollution readings in New Delhi hit their highest of this pre-winter season.

Drone footage of India’s New Delhi showed the world's most polluted capital blanketed in a thick layer of toxic smog. There were similar scenes in Agra, where smog prevented tourists from snapping selfies at the Taj Mahal.

Delhi's air pollution hit "severe" levels on Wednesday as the air quality index (AQI) touched 422 at 6 am. The choking smog engulfed the city, affecting visibility at Indira Gandhi International Airport, where 79 flights were delayed, and six were cancelled, as per Flightradar data.

A thick layer of smog engulfed the national capital on Friday while the air quality index in Delhi remained in the 'very poor' category, according to the Central Pollution Control Board (CPCB). Drone visuals from the Mayur Vihar and Kalindi Kunj areas revealed the thick density of smog.

The Central Pollution Control Board data shows of the 38 monitoring stations in Delhi, nine reported AQI readings in the “severe” range.