Delhi recorded just a single day of ‘Good’ air quality during the entire 92-day monsoon season despite heavy rainfall, according to a new report by the Centre for Science and Environment (CSE).
The report, released on Wednesday (September 30, 2026), noted that the Capital’s ‘Good’ Air Quality Index (AQI) day occurred on July 9, when the combined mean rainfall across the Safdarjung and Palam meteorological stations hit 67.75 mm. The report defied the summer season, as April 1 to May 31 (61 days) and the monsoon as June 1 to August 31 (92 days).
“Out of 92 analysed days, ‘Poor’ days plummeted to just three (3.3 per cent). ‘Satisfactory’ days rose to 35 (38.0 per cent), while ‘Moderate’ days held the single largest share at 53 (57.6 per cent),” the CSE statement noted.
According to the Central Pollution Control Board (CPCB), the AQI scale marks 0–50 as ‘Good’, 51–100 as ‘Satisfactory’, 101–200 as ‘Moderate’, and 201–300 as ‘Poor’.
According to the report, even during the monsoon — when natural atmospheric “washout” and wet deposition effects peak — Delhi’s ambient air quality struggled to sustain clean levels. Despite heavy precipitation, baseline pollution remained elevated, and particulate matter rebounded rapidly within 48 hours of rainfall, it added.
Anumita Roychowdhury, executive director of research and advocacy at CSE, said, “While monsoon rains bring temporary relief, they only mask the underlying crisis. The fact that even heavy rainfall failed to bring consistent ‘Good’ air quality, and that pollution rebounded within 48 hours during dry spells, shows that our baseline emissions remain dangerously high. As we enter winter, we are starting from a baseline where continuous, elevated emissions will inevitably trigger severe seasonal spikes.”
Ms. Roychowdhury added that Delhi cannot rely on nature’s washout in the monsoon or emergency winter bans to manage its air. “What we need is ambitious, year-round, airshed-wide action to permanently cut emissions at their source across all sectors in the NCR,” she said.
Every winter, air pollution spikes drastically across Delhi-NCR and the larger Indo-Gangetic Plains. This seasonal crisis is triggered by meteorological shifts like lower wind speeds and dropping temperatures, and is severely worsened by vehicular emissions, road dust, stubble burning in October and November, and festive firecrackers.
Published – October 01, 2026 12:48 am IST
