New Delhi, Oct 31 (IANS): Bursting of firecrackers on Diwali night has taken pollution in Delhi and NCR on Monday to a "severe" level, showed figures recorded by air monitoring agencies.

A thick layer of smog blanketed several parts of the national capital region affecting visibility in the morning.

According to Central Pollution Control Board, the level of PM 2.5 -- a prominent pollutant -- was 431 microns (average) per cubic metre compared to a safe level of 60.

The PM 2.5 level is particulate matter with a size of less than 2.5 microns that can reach the thinnest arteries of lungs in our body.

The data recorded at the air monitoring stations at Anand Vihar, R.K. Puram, Dilshad Garden, Shadipur, Mandir Marg and Punjabi Bagh (West Delhi) revealed pollution at critically high levels.

System of Air Quality and Weather Forecasting and Research (SAFAR) of the Ministry of Earth Sciences had forecast pollution levels to reach "severe" on October 30 and at "worst" on October 31.

Its data shows that PM 10, which is slightly bigger than PM 2.5 and yet very harmful for the respiratory system, had touched 500 microns per cubic metre compared to a safe level of 100 since Sunday midnight.

Pollution in Delhi peaks to severe level during Diwali as a hazardous mix of harmful gases and pollutants hang very close to the surface. The Delhi High Court had described the capital as "gas chamber" last year.

The pollution levels in neighbouring Agra in Uttar Pradesh and Gurgaon in Haryana were also alarming, as PM 2.5 level touched the figure of 494 and 500, respectively, post Diwali.