Delhi didn’t heed the warnings and yet again paid the price. On Monday, a day after firecrackers were burst around the city to celebrate Diwali, the festival of lights, the capital was encased in a blanket of haze and smog.

According to the Delhi Pollution Control Committee’s real-time ambient air quality data at 10.55 pm on Sunday, particulate matter 10 (particles of soot and other contaminants in the air that are 10 micrometres in diameter and smaller) was recorded at 4,273 micro grams per cubic metre. PM2.5 touched an alarming high at 748 micro grams per cubic metre at 2.30 am, Hindustan Times reported.

PM 2.5 is the pollutant of greatest concern to public health. It has been shown to cause lung cancer, cardiovascular and respiratory diseases, asthma, and a host of other health problems. The permissible limit for PM 2.5 is 60 micro grams per cubic metre.

Skymet, a private weather forecaster, had predicted that the Capital’s air would be significantly more polluted this Diwali than on the festival in the last two years.

Contradicting the information on the air quality data, Delhi Health Minister Satyendra Jain told ANI, "A huge thank you to Delhi as the firecrackers were lesser than last year." He claimed that pollution levels were high in several other cities as well.

Social media users were not amused by Jain's statement, reminding him that Delhi was still on top of the list of the most polluted cities in the world.

Press Trust of India tweeted that visibility on roads on Monday morning was recorded at 200 metres.

ANI shared images of a five-vehicle crash on the Delhi-Noida-Delhi flyover. No injuries were reported. The crash was said to have been caused by the poor visibility on the road.

In 2015, the Delhi High Court had observed that air pollution levels in the national capital had reached alarming proportions, and compared life in the city to living in a gas chamber. The High Court had also asked for an air purifier for its premises.

A report released by the United Nations Children's Fund on Monday said that almost 300 million children live with polluted outdoor air. That makes one in seven children, worldwide, vulnerable to serious physical damage, including to their developing brains.

The United Nation Children's Fund called air pollution a leading factor in child mortality. Around 6 lakh children under age five die every year – more than malaria and HIV/AIDS combined – from diseases caused by or exacerbated by outdoor and indoor air pollution, UNICEF said.