Slideshow ( 3 images )

NEW DELHI (Reuters) - Air quality has been deteriorating over recent weeks in India’s capital New Delhi as farmers burn crop residue in neighboring states and the smoke combines with industrial and vehicular emissions.

The festival of Diwali on Wednesday, when revelers set off firecrackers late into the night, pushed pollution to levels that federal government agencies call “very poor” or “severe”, and hazardous to health.

Reuters set up a camera on top of the Delhi bureau to capture the deterioration in air quality over the past few weeks in the city of 20 million, described the World Health Organisation as the sixth-most polluted city in the world.

The photographs, taken with a fixed camera, are matched with air quality data to illustrate the scale of the problem. Another series of photographs shows air quality at 11 a.m. each day from Oct 20 to Nov 8.

To see the interactive graphic click on tmsnrt.rs/2PiM0Ut