Air quality in Delhi on the morning after Diwali was recorded in the “very poor” category, but the situation was relatively better than in previous years due to favorable weather conditions that dampened the effect of firecrackers and stubble burning. The capital’s Air Quality Index (AQI) was at 326 at 8 am on Tuesday. The neighboring cities of Ghaziabad (285), Noida (320), Greater Noida (294), Gurugram (315) and Faridabad (310) reported “poor” to “very poor” air quality. An AQI between zero and 50 is considered “good”, 51 and 100 as “satisfactory”, 101 and 200 as “moderate”, 201 and 300 as “poor”, 301 and 400 as “very poor”, and 401 and 500 as ” serious”.
Relatively better air this morning does not mean good air. PM2.5 levels at 30 of 35 monitoring stations in the capital were five to six times higher than the national standard of 60 micrograms per cubic meter at 8am. PM2.5 are fine particles that are 2.5 microns or less in diameter and can travel deep into the respiratory tract, reach the lungs and enter the bloodstream.
Although people in several parts of Delhi burst firecrackers despite the ban, the intensity seemed lower compared to the last two years. The Delhi government in September announced a complete ban on the manufacture, sale and use of all types of firecrackers by January 1, 2023, including on Diwali, a practice it has been following for the past two years. Farm fires raged in Punjab and Haryana on Monday, but wind speeds were slightly unfavorable for smoke transport. Therefore, stubble burning’s contribution to Delhi’s pollution (around 10 per cent) was also not “too significant”, said Gufran Beig, Senior Professor, National Institute of Advanced Studies, Indian Institute of Science.
Emissions from firecrackers and farm fires have contributed significantly to Delhi’s PM2.5 pollution on Diwali over the years. Their share was relatively lower this year than in previous years, thanks to less bursting of firecrackers and slightly warmer and windier conditions, which prevented the rapid accumulation of pollutants. Diwali was celebrated on November 4 in 2021 and November 14 in 2020, when temperatures were considerably low and winds calm.
According to the Indian Institute of Tropical Meteorology (IITM) early warning system, the air quality is expected to remain in the ‘very poor’ category during the day (Tuesday) and is likely to improve slightly over the next two days. Delhi recorded a 24-hour average AQI of 312 at 4pm on Monday – the second highest for Diwali in seven years.
Earlier, the city recorded an AQI of 281 on Diwali in 2018. Delhi recorded an AQI of 382 on Diwali last year, 414 in 2020, 337 in 2019, 319 in 2017 and 431 in 2016, according to Central Pollution Control Board data. On Sunday night, the city reported a 24-hour average AQI of 259, the lowest on the eve of Diwali in seven years.
“The proportion of PM2.5 in Delhi’s air has increased, indicating the contribution of firecrackers and stubble burning,” said Beig, also the founding director of the SAFAR Project, a forecasting agency under the Ministry of Earth Sciences. “Although the number of active fires has doubled, the wind direction is NW and the wind speed is moderate (not very favorable for the transport of smoke from farm fires). So the contribution of stubble burning is not very significant,” he said.
Stubble burning is likely to account for 12 to 15 percent of Delhi’s PM2.5 solution on Tuesday, he added. The Indian Agricultural Research Institute reported 1,019 farm fires in Punjab, 250 in Haryana and 215 in Uttar Pradesh on Monday evening.
The System of Air Quality and Weather Forecasting and Research (SAFAR) had earlier predicted that Delhi’s air quality would be recorded in the ‘very poor’ category if no firecrackers burst. In case firecrackers go off like last year, the air quality on Diwali night may drop to “severe” levels, the company said. Delhi Environment Minister Gopal Rai had earlier said that bursting firecrackers on Diwali in the city would carry a jail term of up to six months and a fine of Rs 200.
He said the manufacture, storage and sale of firecrackers here would be punishable with a fine of up to Rs 5,000 and three years imprisonment under Section 9B of the Explosives Act. A total of 408 teams were formed to enforce the ban. Delhi Police has set up 210 teams headed by Assistant Commissioners of Police, the Department of Revenue has set up 165 teams and the Delhi Pollution Control Board has set up 33 teams.
