Winter air in Delhi-NCR remains stifling even with farm fires at a multi-year low. For most of October and November, pollution levels ranged between “very bad” and “severe”, driven by a growing “toxic cocktail” of PM2.5, nitrogen dioxide (NO₂) and carbon monoxide (CO) emitted mainly from vehicles and other local sources.
At least 22 air quality monitoring stations in Delhi recorded carbon monoxide (CO) levels above permissible limits for more than 30 of the 59 days assessed, with Dwarka Sector 8 recording the highest number of violations at 55 days, followed by Jahangirpuri and Delhi University’s North Campus, both at 50 days, according to a new analysis (CSE for Science and Environment) (CSE).
The analysis also highlights the worrying spread of pollution hotspots in the capital.
In 2018, only 13 places were officially designated as hotspots. Now, several other places routinely record pollution levels much higher than the city average.
Jahangirpuri emerged as Delhi’s most polluted hotspot with an annual PM2.5 average of 119 µg/m³ or micrograms per cubic metre, followed by Bawana and Wazirpur (113 µg/m³), Anand Vihar (111 µg/m³) and Mundka (03 ok, Rohini µg/m³).
Vivek Vihar, Alipur, Nehru Nagar, Siri Fort, Dwarka Sector 8 and Patparganj were some of the new hotspots identified by the CSE.
Smaller NCR cities also experienced more intense and prolonged smog episodes this year.
Bahadurgarh experienced the longest continuous smog event – which lasted for 10 days, from November 9 to 18 – indicating that the region is increasingly behaving as a single air duct with uniformly high pollution levels.
The CSE assessment found that early winter pollution has stabilized at unhealthy levels, driven mainly by local emissions, although the contribution of stubble burning has fallen significantly.
The analysis – based on CPCB data – points to a “toxic cocktail” of PM2.5, nitrogen dioxide (NO₂) and carbon monoxide (CO), pollutants closely associated with vehicles and combustion sources, which has increased health risks this season.
The researchers found that PM2.5 levels rose and fell almost simultaneously with NO₂ during rush hours. Between 7–10 a.m. and 6–9 p.m., both pollutants spiked as vehicular emissions accumulated beneath the shallow winter boundary layers.
While NO₂ showed fast peaks associated with traffic, PM2.5 showed broader and slower moving peaks. CO levels also breached the eight-hour standard at several locations across the city.
“This synchronized model reinforces that particle pollution peaks are driven by traffic-related NO₂ and CO emissions on a daily basis, particularly under low-dispersion conditions,” said Anumita Roychowdhury, Executive Director (Research and Advocacy), CSE.
“Yet winter control efforts are still dominated by dust measures with weak effects on vehicles, industry, waste incineration and solid fuels,” she added.
The report said that stubble burning in Punjab and Haryana was significantly subdued this year, partly because floods disrupted the crop cycle.
For most of the early winter period, farm fires contributed less than 5% to Delhi’s pollution, increasing to 5–15% on some days and on 12–13 reached a peak of 22% in November.
While the decline in stubble burning has prevented extreme swings in pollution, it has done little to improve daily air quality, the report said. PM2.5 remained the dominant pollutant for 34 days, followed by PM10 after 25 days, ozone after 13 days and CO after two days.
Throughout November, the AQI remained in the “very poor” to “severe” range, underscoring the continued impact of Delhi’s local sources of pollution – transport, industry, waste incineration and domestic fuel consumption.
Although peak pollution levels this year were lower compared to the last three winters due to lower impacts from firecrackers and farm fires, average pollution levels showed almost no improvement.
PM2.5 levels for October to November were about 9% lower than last year, but no significant progress was seen from the three-year baseline.
Between 2018 and 2020, PM2.5 levels saw a steady decline, partly due to the pandemic. However, from 2021–22, annual averages have stabilized at elevated levels.
In 2024, the annual average increased sharply to 104.7 µg/m³, reversing earlier gains.
The report recommends a set of deep structural measures to tackle emissions across sectors – time-bound electrification targets, phasing out older vehicles, expanded public transport and last-mile connectivity, and better infrastructure for walking and cycling.
He also calls for parking caps, congestion taxes, cleaner industrial fuels, lower gas taxes, elimination of waste incineration, better waste sorting and remediation of old landfills.
On Monday (December 1, 2025), Delhi’s AQI at 3:00 pm was 303, placing it in the “very poor” category, according to CPCB’s air quality bulletin.
Published – 01 Dec 2025 17:36 IST
