Delhi has recorded its lowest average air quality index (AQI) for the November 1–15 period in three years, yet residents continued to inhale air that remained firmly in the “very poor” to “severe” category. This year’s average AQI of 349 is only marginally lower than 367 in 2024 and 376 in 2023, and barely above 345 in 2022 a shift too small to offer any real relief.
Experts cautioned that this decline should not be mistaken for cleaner air. They attributed the lower readings to a combination of meteorological luck, a delayed surge in stubble burning due to flooding in Punjab, and an unusually early Diwali that took place before winter’s pollutant-trapping inversion layer could settle. In addition, irregularities in Delhi’s air monitoring network including missing values and suspicious readings may be obscuring the actual pollution levels.
For years, the Delhi Pollution Control Committee has identified November 1–15 as the city’s most polluted stretch, with farm fires, fireworks, and cold, stagnant air merging into a seasonal chokehold. Between 2018 and 2023, this period averaged an AQI of 371. But this year, with Diwali falling on October 20, temperatures had not dipped enough to trap pollutants near the surface.
Stubble burning also remained lower than usual. Punjab reported 4,877 farm fires between November 1 and 15, compared to 7,864 last year, largely because floods delayed the harvest and subsequent burning. Haryana too saw a drop, with 516 fires compared to 1,055 last year. The Decision Support System showed a peak stubble-burning contribution of 22.47% — significantly below the highs of 2020, 2022, and 2023, and far lower than the 48% peak in 2021. However, gaps in DSS data on November 15 and 16 raised further concerns about overall accuracy.
Those concerns deepened after the discovery of inconsistent data across several of Delhi’s 39 monitoring stations. Static readings, missing values, and improbable fluctuations were observed. On November 10, for example, while most stations reported “severe” pollution, the NSIT Dwarka monitor showed “moderate” PM2.5 levels, swinging between very low and very high values in a pattern experts deemed unlikely.
According to Sunil Dahiya of EnviroCatalysts, the slight improvement in numbers should be interpreted cautiously. He warned that while the AQI may appear lower, the reliability of the data itself has diminished this year. The delayed spike in farm fires, he added, may also have artificially reduced the early November average.
During this fortnight, CPCB data shows three “severe” days, ten “very poor” days, and two “poor” days. Last year’s count included two severe days and thirteen very poor days. Meteorology provided some temporary relief, with stronger winds dispersing emissions. Former CPCB air laboratory chief Dipankar Saha said continued winds could keep pollution from slipping back into the severe zone.
However, this relief may be short-lived. The Air Quality Early Warning System has predicted a return to “severe” conditions from Monday through Wednesday, with Delhi expected to fluctuate between very poor and severe for at least six days. At 4pm on Sunday, the city’s AQI was 377 firmly in the “very poor” category.
Beyond November, Delhi generally enters its second-worst pollution phase between December 15 and 31, when dense fog and wedding-season traffic push the average AQI to 354. This is followed by the January 1–15 period, with an average AQI of 324 still far from what could be considered breathable air.