On Diwali Monday, the air quality in Delhi became "very poor" due to an increase in stubble burning, firecracker bursting, and moderately unfavourable meteorological conditions that allowed pollutants to accumulate, news agency PTI reported.
According to the Swiss organisation IQAir, Delhi was the most polluted city in the world on Diwali, followed by Lahore in Pakistan. Despite this, the 24-hour average air quality index (AQI) of 312 was the second best for Diwali in seven years. Prior to this, the city had an AQI of 281 on Diwali in 2018.
Ghaziabad (301), Noida (303), Greater Noida (270), Gurugram (325), and Faridabad (256) were among the cities with poor to very poor air quality.
The city reported a 24-hour average AQI of 259 on Sunday evening, the lowest for the day before Diwali in seven years, PTI reported.
As people set off firecrackers in various parts of the national capital and farm fires raged across Punjab and Haryana, pollution levels crept up at night, despite a drop in temperature and wind speed.
Due to the moderate wind speed and warm conditions, the air quality remained largely stable during the day.
According to data from the Central Pollution Control Board (CPCB), Delhi had an AQI of 382 on Diwali last year, 414 in 2020, 337 in 2019, 319 in 2017, and 431 in 2016.
An AQI of zero to 50 is regarded as "good," 51 to 100 as "satisfactory," 101 to 200 as "moderate," 201 to 300 as "poor," 301 to 400 as "very poor," and 401 to 500 as "severe."
However, low temperature, calm winds and emissions from firecrackers at night may push the air quality deep into the "very poor" category or even the "severe" zone by early Tuesday morning. "The share of PM2.5 in Delhi's air has increased which is indicative of contribution from firecrackers and stubble burning," said Gufran Beig, Chair Professor, National Institute of Advanced Studies, Indian Institute of Science, PTI reported.
"Though the active fire counts have doubled, the wind direction is north westerly and the wind speed is moderate (not very favourable for the transport of smoke from farm fires). Hence, the contribution of stubble burning is not very significant," he stated.
Beig said the air quality in the national capital may plunge to the "severe" zone in the wee hours Tuesday but improved wind speed and warm conditions during the day will help disperse pollutants.
"Therefore, the air quality is likely to retreat to the 'very poor' category on Tuesday itself," he said.
Stubble burning is likely to account for 12 to 15 percent of Delhi's PM2.5 solution on Tuesday, the scientist said.
People began bursting firecrackers in several parts of Delhi early Monday evening, defying the Delhi government's ban with impunity.
Environment Minister Gopal Rai previously stated that bursting firecrackers on Diwali in the city would result in a six-month jail sentence and a Rs 200 fine.
According to Section 9B of the Explosives Act, the manufacture, storage, and sale of firecrackers in India will be punishable by a fine of up to Rs 5,000 and three years in prison.
A total of 408 teams have been set up to implement the ban. The Delhi Police has set up 210 teams under assistant commissioners of police, while the revenue department has set up 165 teams and the Delhi Pollution Control Committee has constituted 33 teams, PTI reported.
(With Inputs From PTI)