A policewoman at a Delhi junction during restrictions on private vehicles based on registration plates, on November 4, 2019. (Photo: Reuters)

Air quality in the Delhi area has dipped slightly overnight and climbing levels of dangerous particulate matter are being reported across the region on Thursday morning.

Data from the Delhi Pollution Control Commitee and the Central Pollution Control Board, published here, show that levels of PM 2.5 -- particulate matter less than 2.5 microns in diameter that lodge deep in the lungs -- have climbed to very unhealthy levels in most parts of the Delhi and the NCR.

For example, based on the most recent updates as of 9.34 am, the PM 2.5 levels in Sector 16A Faridabad and Sanjay Nagar in Ghaziabad were 278 and 275, respectively.

Air pollution in Delhi, one of the world's most polluted cities, has been the subject of intense public debate -- as it usually during the onset of winter -- and has received international attention.

On Wednesday, the Supreme Court sharply criticised both central and state governments for not doing enough to limit pollution and the burning of crop stubble in Punjab and Haryana, a factor contributing to Delhi's plight.

The court asked if the governments did not feel ashamed that flights were being diverted, and that citizens weren't safe in their homes.

Air quality has generally improved in the capital since Sunday, when it was caught in a disastrous air choke. Schools in New Delhi reopened on Wednesday after a two-day closure.

On Tuesday night, more than 1,500 people gathered at India Gate to protest high pollution levels and demand action from the central and state governments.

Inputs from IANS and Reuters