India’s airpocalypse: The story of Diwali peaks, missing data, and stubble-burning build-up, in charts

Post-Diwali firecracker smoke, combined with seasonal stubble burning and cold winter air, causes dangerous air quality deterioration across northern India. The peak-hour spikes are so severe that they result in data blackouts.

Like clockwork, Delhi and surrounding regions wake up to grey smog a day after Diwali celebrations. The visibility is poor; the metallic smell of fine particles is strong. And the data lays bare readings so high that air pollution stations go blank for hours, raising questions about the readings' robustness and serving as a reminder of Diwali's brutal impact on air pollution.

While Delhi makes headlines, over 200 cities also recorded a sharp deterioration in air quality following Diwali, mainly in northern and central regions. It’s not just Diwali—stubble burning added to woes leading up to Diwali. And now winter’s cold air will trap pollution near the ground, making clean air a distant dream at least until February.

Choked city

Diwali celebrations trigger a severe environmental crisis every year as air pollution levels surge five to seven times their levels within hours. A Mint analysis of PM2.5—a measure of microscopic, toxic air particles that can penetrate deep into your lungs—at 15-minute intervals by the Central Pollution Control Board (CPCB) across 59 air pollution stations in Delhi shows that the levels begin rising around 5 pm on Diwali day and skyrocket between midnight and 2 am to around 500-700 μg/m³ following the festivities.

In simpler terms, these levels are equivalent to smoking at least 25 to 26 cigarettes in a single day. Data from 2023 through 2026 demonstrates that this post-Diwali surge is a recurring annual phenomenon rather than an anomaly. The pollutants reached dangerously high levels in 2025-2026, even as the Supreme Court permitted the use of only certified green crackers between 6 am and 7 am and 8 pm and 10 pm around Diwali, highlighting severe policy failure in addressing the recurring issue.

Data darkness

Soon after Diwali lights up the entire country, the spike in air pollution leads to severe data darkness. A Mint analysis of 15-minute interval PM2.5 data for 24 hours between 12 pm on 8 November and 12 pm on 9 November shows that out of 5,664 data points, only 4,439 were available, accounting for 22% missing data, up from 14% three years ago.

These missing data points, spread across at least 35 stations, were mostly concentrated around midnight when pollutant levels spiked on 9 November. This often results from sensor saturation (as hardware measuring limits max out at 1,000 μg/m³), while filter tapes clogged by heavy particulates trip automatic safety shut-offs.

Separate PM2.5 data from the Delhi Pollution Control Committee (DPCC) shows that the readings reached as high as 3,744 at Mundka around 2 am on 9 November. Out of the 30 stations, 11 recorded readings above 2,000 for a brief period post-celebrations, raising questions over data robustness and underestimation of levels during peak hours by the CPCB.

National after-effects

Delhi’s air pollution levels are notoriously high, but several other cities also witness a sharp post-Diwali deterioration in the air quality index (AQI). On Diwali, 191 cities had moderate or worse air quality, but a day after the celebration, the number of cities in these categories rose to 246.

In fact, the worst 24-hour reading on 9 November was not in Delhi but in Bahadurgarh in Haryana, where the AQI level reached the severe level of 400. Of the 278 cities for which the AQI data was available for both 8 and 9 November, 213 saw their AQI levels rise.

Out of these, 30 cities witnessed increases of more than 100 points in AQI. Some cities in Bihar stood out: Bettiah and Arrah recorded the highest post-Diwali increases—in excess of 200 points on the index—pushing their air quality from good/satisfactory levels, respectively, on Diwali into the ‘poor’ zone the next day. As many as 51 cities slipped from good/satisfactory levels to moderate/poor levels.

Burning build-up

The brutal impact of Diwali celebrations is undeniable, but it would be wrong to simply attribute it to a few days of firecrackers on months of poor air quality, especially in the northern region of India. Delhi’s air quality index (AQI) levels were already in the “very poor” category ahead of Diwali due to colder air trapping pollutants near the ground, as well as the effect of stubble burning in the days ahead.

Data from the Indian Institute of Tropical Meteorology shows that the contribution of stubble burning to Delhi’s PM2.5 levels began rising from 20 October and reached as high as 16.3% on 4 November, before easing somewhat to 5% on 8 November.

The build-up in pollutants ahead of Diwali adds to woes every year. A study published by Atmospheric Chemistry and Physics in July 2026 said that India’s open burning emissions contributed 8% to annual PM2.5 levels across India in 2022. While these levels may be smaller than 18% from industry and 15-16% from residential and power generation, the timing of stubble burning in October-November makes matters worse.

About the Authors

Pragya is the Editor of Plain Facts, the specialized data journalism vertical at Mint, where she leads a team dedicated to uncovering the stories hidden within complex datasets. Since taking the helm of the section in 2025, she has leveraged over a decade of journalistic expertise to bridge the gap between abstract numbers and storytelling.<br><br>Pragya has distinguished herself through rigorous data work on India’s most critical economic and social indicators in the last eight years. Her portfolio includes deep dives into the complexities of India’s GDP calculations, nuanced critiques of government datasets and surveys, and in-depth analysis of the Time-Use Survey. The latter notably highlighted the profound ways in which marriage reshapes the lives and labour of Indian women.<br><br>Pragya started her journey as a copy editor and a reporter at the Press Trust of India (PTI) in 2016. Her interest in data analysis led her to The Financial Express and Cogencis, where she got opportunities to examine India's public statistics through a rigorous lens. This was further cemented when she joined Plain Facts in 2021. She maintains that while data and charts drive the narrative, they must remain anchored in rigorous journalism—providing the essential context and relevance needed to influence both public policy and everyday lives.

Rupanjal Chauhan is a data journalist at Mint, where she contributes to the Plain Facts and Data Bites sections, focusing on translating complex datasets into clear, insightful, and engaging narratives for a wide audience. Her work focuses on using data to explain policy, economic, and social trends in a clear and accessible way.<br><br>At Mint, her work spans public finances, trade, geopolitics, and employment, often breaking down large datasets into sharp, evidence-backed stories. Her approach focuses on careful data analysis and clear storytelling, ensuring that each piece not only informs but also enables readers to better understand the forces shaping India’s economy and society.<br><br>Rupanjal holds a postgraduate diploma in digital media from the Indian Institute of Mass Communication (IIMC), New Delhi, where she specialised in data-driven storytelling and digital journalism. She also has a bachelor’s degree in journalism and mass communication from St. Xavier’s College, Ranchi. Her work is guided by a focus on simplifying complex data without losing nuance, with an emphasis on accuracy, transparency, and context, helping readers better understand the patterns and trends behind the numbers.