New Delhi: A day after millions celebrated Diwali across the country, pollution levels in Delhi and its neighbouring areas soared as people defied the ban on firecrackers.

Sparklers were seen lighting up the night sky while crackers went off on the ground in various areas.

The air quality in the national capital plunged to "severe category", worsening the pollution caused by burning farm waste in neighbouring states.

The average AQI in Delhi at 8am stood at 468. Doctors and scientists say that short term exposures to high levels of PM 2.5 can cause severe health problems including worse coronavirus infections. It can also worsen blood pressure and asthma.

Almost all the areas in the city logged PM2.5 levels above 400 with many regions nearing the alarming 500-mark. The Air Quality Index (AQI) for PM 2.5 pollutant stood crossed 800 in most parts of the capital on the night of Diwali.

The National Green Tribunal (NGT) had on Monday imposed a total ban on sale or use of all kinds of firecrackers in the National Capital Region (NCR) till November 30 midnight.

The Delhi government too had earlier this month imposed a total ban on all kinds of fireworks till November 30.

A doctor in Kailash Hills area said, "Everyone was posting images of clear blue skies during the COVID-19 lockdown. Now, we all can see how bad the pollution is. Bursting of cracker will make things worse."

"The Delhi government has banned it, but you can see what is happening," he said.

The Delhi Police, however, said that it has deployed personnel in many parts of the city and action will be taken against those violating the ban.

"We have deployed adequate police personnel to check illegal sale and bursting of fire crackers. Today also, personnel have been deployed and action will be taken against the offenders," a senior police officer said.