Traffic, not stubble burning, behind Delhi’s pollution spike: Study

Even with farm fires at a multi-year low, Delhi-NCR’s winter air remains polluted. For most of October and November, AQI levels hovered between ‘very poor’ and ‘severe’.

A new analysis by the Centre for Science and Environment (CSE) shows that emissions from vehicle and other local sources are mainly responsible for daily pollution spikes in the Capital. This has created a daily “toxic cocktail” of PM2.5, nitrogen dioxide (NO2) and carbon monoxide (CO).

Of the 22 monitoring stations assessed, CO levels crossed permissible limits on more than half the days. Dwarka, Sector 8, recorded the highest number of violations at 55 days, followed by Jahangirpuri and Delhi University’s North Campus at 50 days each.

The study also notes a sharp increase in pollution hotspots across the city. In 2018, there were 13 official hotspots. Now, several more locations routinely record levels far higher than the city average.

Jahangirpuri emerged as most polluted hotspot this year with an annual PM2.5 average of 119 micrograms per cubic metre, followed by Bawana and Wazirpur at 113, Anand Vihar at 111, and Mundka, Rohini and Ashok Vihar between 101 and 103. The CSE also flagged Vivek Vihar, Alipur, Nehru Nagar, Siri Fort, Dwarka Sector 8 and Patparganj as new hotspots.

Smaller NCR towns recorded longer and more intense smog episodes this year. Bahadurgarh saw the longest continuous smog event – lasting 10 days from November 9 to 18, which, the CSE says, shows how the entire region increasingly behaves like a single polluted airshed.

CSE’s assessment finds that early winter pollution has now plateaued at unhealthy levels and is being driven mainly by local emissions. Stubble burning was significantly lower this year because floods disrupted the crop cycle in Punjab and Haryana. For most of the early winter period, farm fires contributed less than 5 per cent to Delhi’s pollution. The contribution rose briefly to between 5 and 15 per cent on some days and touched 22 per cent only on November 12 and 13.

Traffic-related emissions showed a clear daily pattern. PM2.5 rose and fell almost in sync with NO2 during peak traffic hours between 7 am and 10 am and 6 pm and 9 pm when pollutants remained trapped under shallow winter boundary layers. CO levels also crossed the eight-hour standard at several stations.

“This synchronised pattern reinforces that particulate pollution spikes are being fuelled daily by traffic-related emissions, especially under low-dispersion conditions,” said Anumita Roychowdhury, executive director, research and advocacy at the CSE.

She said winter control measures continue to focus mainly on dust while action on vehicles, industries, waste burning and solid fuels remains weak.

Despite fewer firecracker emissions and reduced farm-fire impact, long-term improvements in air quality remain limited. PM2.5 levels for October and November were about 9 per cent lower than last year, but the three-year baseline shows no significant progress. After improvements between 2018 and 2020, annual PM2.5 averages have stagnated since 2021 and 2022. In 2024, the annual average rose to 104.7 micrograms per cubic metre, reversing earlier gains.

The CSE has called for structural measures such as time-bound electrification, strong vehicle scrappage push, expanded public transport, better last-mile connectivity and improved walking and cycling infrastructure. It has also recommended congestion taxes, parking caps, cleaner industrial fuels, reduced gas taxes, end to waste burning, stronger waste segregation and remediation of legacy dumpsites.

Sharp dip in farm fires burning in 2025

• Lowest farm fires in five years recorded in Punjab and Haryana during the 2025 paddy harvesting season.
• Punjab logged 5,114 fire incidents, a 53% drop from 2024 and a reduction of over 90% compared to 2021.
• Haryana reported 662 incidents, also down 53% from last year and 91% lower than 2021.
• A dedicated CAQM Cell in Chandigarh is now monitoring stubble management round the year.
• The CAQM said the sharp reduction in farm fires helped prevent severe pollution episodes in Delhi-NCR this season.