Bengaluru: With the Supreme Court permitting ‘green’ firecrackers and citizens bursting fireworks of all kinds well beyond permitted time limits on Diwali (October 20), the air quality in the capital city dipped to the “very poor” category in many locations post-Diwali.Some locations in New Delhi recorded fine particulate matter levels of more than 1,750 micrograms per cubic metre, which is nearly 30 times the permitted national standards for the major air pollutant. Government data published by the Central Pollution Control Board (CPCB) showed that hourly levels of fine particulate matter was the highest it has ever been post-Diwali for the past four years.Experts have also cast aspersions on not only the efficacy of green firecrackers, but also the data recorded by government-installed air quality monitors, with the government’s open-access websites that provide real time monitoring of air quality being unavailable for several hours during peak firecracker time on Diwali day. Pollution levels peakIndia celebrated Diwali, the Hindu festival of lights, on October 20. A few days before, the country’s apex court had permitted the manufacture, sale and use of ‘green’ firecrackers by rationalising that such crackers cause lesser pollution than ordinary crackers. However, as The Wire has reported before, ‘green’ crackers still emit 70% of the emissions that normal crackers do and are, therefore, still polluting. On Diwali night and 24 hours later, levels of fine particulate matter (PM2.5) peaked in several locations in the city.According to a report by the Times of India, PM2.5 concentration between 9 PM and 10 PM on Diwali night, Monday, at Nehru Nagar in Lajpat Nagar increased from 679 micrograms per cubic metre (µg/m3) to a whopping 1,763 µg/m3, making the area the most polluted in the city. This is more than 29 times the daily national ambient air quality standard of 60 µg/m3 for PM2.5, and 118 times the World Health Organisation’s daily safe guideline.Anand Vihar showed a peak hourly concentration of 1,710 µg/m3, R.K. Puram witnessed fine particulate levels of 1,476 µg/m3 and west Delhi’s Punjabi Bagh clocked 1,432 µg/m3. Per the report, hourly PM2.5 concentrations surpassed 1,000 µg/m3 at 14 of the 20 stations run by the Delhi Pollution Control Committee. During last year’s Diwali, only five stations exceeded this threshold.In fact, government data on the concentrations of fine particulate matter published by the CPCB shows that Delhi had the highest levels of post-Diwali pollution this year when compared to the past four years. Hourly averages of fine particulate matter (PM2.5, which are inhalable particles smaller than 2.5 micrometers in diameter, and are emitted by firecrackers) across four years (2021-2025) show a worrying trend.On Diwali nights, PM2.5 values increase sharply, peaking either late at night or early morning after the festival. However, 2025 showed the highest recorded mean (488 µg/m³) and maximum concentration (675.1 µg/m³) post-Diwali (on October 21), indicating a severe pollution buildup in the capital city, according to an analysis by Climate Trends, an environmental research and media consultancy firm. Compare this to the other years: 454.5 µg/m³ in 2021 the day after Diwali, 168 µg/m³ in 2022, 319.7 µg/m³ in 2023 and 220 µg/m³ in 2024. Pollution levels not only rose high, but also stayed high for longer this Diwali.Spikes in pollution levels from firecracker emissions typically last a few hours, said air pollution researcher Sunil Dahiya, founder of Delhi-based research think tank EnviroCatalysts. “We have typically seen that the pollution levels build till 1 AM and start declining, but this year the spike plateaued for a few hours, and came down slowly compared to past years meaning stagnation of pollution for longer than previous years,” he said.Green crackers pollute“It is most likely that the high concentration of PM 2.5 is due to local emission of firecrackersin the different parts of the city on this auspicious Diwali festival night,” said atmospheric researcher S.K. Dhaka, professor at Rajdhani College, University of Delhi, in a statement.Wind speed was low, he added, and hence there was no chance for pollutants to have been transported from one place to another in a short span of a few hours of firecrackers being burst. All evidence points to the fact that green firecrackers enhanced the particulate matter at a “rapid rate”, he noted. He also noted that the pollution was of a local nature, and not due to transport from other places.“It suggests that we need to check the quality of the green firecrackers,” Dhaka said.“Some percentage reduction in pollution from a source doesn’t make it green and it wasn’t part of our original tradition to burst crackers, so to eliminate this hazardous source of pollution from our festive celebration is the only way to celebrate the festival with love for not just ourselves as humans, but for pets and animals as well,” Dahiya commented. “The so-called green crackers also emit even smaller particles which can penetrate even deeper inside the human body, causing more damage,” he added.Citizens also flouted the rules pertaining to the permitted time period (from 6 AM to 7 AM and from 8 PM to 10 PM on Diwali and the day before) for bursting crackers in the city, and went way beyond the time limit. The crackdown was poor: the Delhi Police registered only around 150 cases across the city on citizens violating this rule.However, the government does not agree that this year’s Diwali was one of the most polluted either. Right after Diwali, Delhi chief minister Rekha Gupta claimed that pollution has decreased this year post-Diwali when compared to previous years. VIDEO | Delhi CM Rekha Gupta (@gupta_rekha), addressing a press conference, said, “Diwali pollution is lower than in past years under previous governments.”#AirPollution #DelhiPollution(Full video available on PTI Videos – https://t.co/dv5TRAShcC) pic.twitter.com/wfRIVYovF2— Press Trust of India (@PTI_News) October 22, 2025Talking to the media on October 22, Gupta claimed that ‘data’ had shown that pollution was indeed less and that the government was doing everything possible about it. However she did not cite what data she was referring to. Disappearing dataMeanwhile, a few hours into Diwali evening, there was a data blackout: the government’s open-access websites that provide real-time monitoring of air quality were unavailable for several hours. The Wire tried accessing data published by the Indian Institute of Tropical Meteorology on the evening of October 20 but the website did not open.Many stations blanked out on the night of Diwali and did not provide data on pollution levels. This was an issue with stations run by all four monitoring agencies – the Indian Institute of Tropical Meteorology, India Meteorological Department (IMD), the Delhi Pollution Control Committee and Central Pollution Control Board, Dahiya commented.“The observed pattern shows that most stations stopped providing data when they approached 1000 µg/m³, while there were stations such as Anand Vihar, Nehru Nagar, Mundka etc that recorded values above 1000 µg/m³. indicating that technology of monitoring isn’t an issue at least in terms of being available,” Dahiya told The Wire.“This is not the first time that the stations have stopped providing data, we have observed this over the past years too. If the issue is technological in the sense that some of these stations can’t monitor beyond a certain limit, these stations should be upgraded to similar technology as Anand Vihar and Nehru Nagar, or if the issue was manual, it should be investigated thoroughly and not be repeated in future,” he added. “Such missing data hampers data driven insights, understanding contribution of certain activities, their impact on health as well as skews the daily pollution level recordings, giving a false sense of lower air pollution levels.”It is no surprise then that experts have also raised questions about the credibility of the data on fine particulate matter published by government websites.“Why was the CPCB’s continuous tracking of PM2.5 and PM10 for GRAP [Graded Response Action Plan] data unavailable from 7 PM on 20th October to 6 AM on 21st October? How did the AQI [Air Quality Index] remain nearly unchanged – 343 at 5 PM on 20th October and 347 at 6 AM on 21st October – despite widespread celebrations? Why did most DPCC monitoring stations show missing data between 11 PM and 6 AM during that critical window?,” asked a former DPCC scientist.“If this was merely a coincidence, so be it. But the citizens of Delhi have a right to know – what exactly did they breathe during those few crucial hours of “Green Deepavali”,” the scientist, who did not wish to be named, asked.‘SC order did not help’The Supreme Court’s order permitting the bursting of green crackers did not help because it legalised the manufacture, sale and use of such crackers even though they produce only 30% lesser pollutants, Delhi resident Praveen Rao told The Wire.This ‘legal’ pressure meant that citizens who did not want firecrackers could not speak out about the indiscriminate bursting of crackers, Rao, who is an advocate by profession, said.“Our politicians are also taking us for a ride by citing religious reasons for permitting crackers and claiming that this is a way to protect Hinduism,” Rao told The Wire. “If we were to celebrate Diwali as we did during the time of Ram [Hindu god associated with the festival] then we should only be lighting diyas [lamps]. Privilege is also a huge factor. People who can afford it burst crackers, but they are protected in their air-conditioned homes with air purifiers running overtime. “It is the poor who will suffer the consequences, they do not even have access to health insurance if they show symptoms of illness due to the bad air quality.“We cannot afford even 10% more pollution,” Rao added.