Skies over Delhi hung heavy with smoke and its air quality inched towards “severe” category on Diwali night as people burst firecrackers in a blatant disregard to the government’s ban against it.

The situation was aggravated further as the festivities were coincided with seasonal farm fires, fumes from which invade the national capital around winter.

People from several parts of the city and its suburbs complained of itchy throat and watery eyes, as a layer of smog, the first episode this season, enveloped the environment, news agency PTI reported.

Residents of Lajpat Nagar in south Delhi, Burari in north Delhi, Paschim Vihar in west Delhi and Shahdara in east Delhi reported incidents of firecracker bursting as early as 7pm, despite the blanket ban in the national capital till January 1, 2022.

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Several incidents of bursting of high-intensity crackers were reported from Gurugram and Faridabad.

The Haryana government had also imposed a ban on Sunday on the sale or use of all kinds of firecrackers in 14 of its districts in the National Capital Region, while curbs were put in other parts.

Experts predicted the air quality here may plunge to the severe category by midnight owing to unfavorable meteorological conditions — calm winds, low temperature and low mixing height — and a poisonous cocktail of emissions from firecrackers, stubble burning and local sources.

The India Meteorological Department (IMD) said the “first episode of fog” in the capital reduced visibility at the Indira Gandhi International Airport and the Safdarjung Airport to the range of 600-800 metres in the morning.

“It continued to remain in the poor range of 800-900 meters in smog throughout the day due to calm wind conditions,” senior IMD scientist R K Jenamani was quoted as saying by PTI.

The first episode of smog coincided with the share of farm fires in Delhi’s pollution increasing to the season’s highest at 25%.

“The PM2.5 pollution in the national capital may enter the ‘severe’ zone by midnight even if there is only 50% of firecrackers emission as compared to last year,” said Gufran Beig, the founder-project director of SAFAR.

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The PM2.5 pollution will shoot up rapidly by Friday early morning with the AQI even crossing the 500 mark, he said.

According to the Central Pollution Control Board (CPCB), the 24-hour average PM2.5 concentration in Delhi-NCR stood at 243 micrograms per cubic meter at 6 pm, more than four times the safe limit of 60 micrograms per cubic meter.

The national capital’s 24-hour average air quality index (AQI) stood at 382 on Thursday, up from 314 on Wednesday. It was 303 on Tuesday and 281 on Monday.

AQI between zero and 50 is considered ‘good’, 51 and 100 ‘satisfactory’, 101 and 200 ‘moderate’, 201 and 300 ‘poor’, 301 and 400 ‘very poor’, and 401 and 500 ‘severe’.

“The extremely calm wind conditions in Delhi and 25 per cent stubble share (fire count 2,293) are two major factors today,” SAFAR said.

As per SAFAR model forecasts, the stubble burning share may increase to 35 per cent on Friday and 40 per cent on Saturday with the wind direction changing to northwesterly.

Northwesterly winds carry smoke from farm fires in Punjab and Haryana towards the national capital.

“Relief is expected only from the evening of November 7 but AQI will fluctuate within ‘very poor’ range,” the air quality forecast agency said.

Last year, the share of stubble burning in Delhi’s pollution had peaked at 42 per cent on November 5. In 2019, crop residue burning accounted for 44 per cent of Delhi’s PM2.5 pollution on November 1.

The contribution of stubble burning in Delhi’s PM2.5 concentration was 32 per cent on Diwali day last year as compared to 19 per cent in 2019.

On October 27, the Delhi government had launched the ‘Patakhe Nahi Diye Jalao’ campaign to create awareness against the bursting of crackers.

Under the campaign, action can be taken under relevant IPC provisions and the Explosives Act against anyone found burning crackers.

According to the government, more than 13,000 kg of illegal firecrackers have been seized and 33 people arrested so far under the anti-cracker campaign.

Experts warned that emissions by firecrackers, if unchecked, could exacerbate already unfavourable meteorological conditions — including slow winds and below-normal temperatures, and the impact of stubble fires in neighbouring Haryana and Punjab.