Toxic pollutants from vehicular plumes — nitrogen dioxide (NO₂) and carbon monoxide (CO) — have shown a surge this early winter, a new analysis by the Centre for Science and Environment (CSE), an independent Delhi-based think tank, has flagged. The assessment, released on Monday, mapped early winter trends from October to November this year.
The study noted that even with a “lesser contribution of farm fires” — that was below 5 per cent on most days, between 5 to 15 per cent on a few days, and peaking at 22 per cent on November 12-13 — the air quality remained poor, indicating the high impact of year-round local sources.
The CSE’s earlier assessments have found a strong correlation between traffic congestion and elevated NO₂ levels, especially during peak hours on working days when travel speeds fall. Multiple studies — both global and national — have also linked exposure to traffic pollutants with excess morbidity and mortality among drivers, commuters, and people living near major roadways, including triggering and worsening respiratory diseases.
The study has identified Vivek Vihar, Ashok Vihar, Nehru Nagar, Alipur, Siri Fort, Dwarka Sector 8, and Patparganj as emerging hotspots, noting that these locations “have remained persistent hotspots for four consecutive years”. It said that the Delhi government needs to take action like it did in 2018, even outside the 13 identified hotspots.
Another key finding shows that smaller NCR towns witnessed worse smog episodes during high-intensity pollution days.
“Several NCR cities remained just as polluted as Delhi, and often worse, with towns like Bahadurgarh recording significantly higher smog intensities during this period. A region-wide smog episode affected NCR towns, but it was Bahadurgarh that endured the most persistent conditions, with the episode lasting a full 10 days, from 9 to 18 November,” it stated.
Bahadurgarh recorded an average smog intensity of 343 µg/m³, nearly 1.2 times of Delhi’s average. This shows that the region now behaves as a single air-shed where smaller towns are no longer cleaner gaps, but pollution hotspots facing equal or greater pressure.
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The pattern of local sources driving PM2.5 levels is well established. Last year, the CSE found that even when stubble-burning impact was minimal at 0.7 per cent between October 10 and 20, particulate concentrations remained high and the city saw no “good” air days. Experts have repeatedly warned that Delhi’s baseline emissions stay elevated throughout the year and only worsen during episodic events like farm fires.
In its recommendations, the CSE called for deep structural changes mainly in vehicular sector, such as meeting vehicle electrification targets with strict timelines, scrappage of older vehicles, scaling up integrated public transport with last-mile connectivity and walking-cycling infrastructure and restraining personal vehicle use through parking caps, pricing, and congestion tax. Other recommendations include a focus on enabling industry to switch to affordable cleaner fuels with stringent emission norms, lowering natural gas taxes and electrifying industrial processes. It has also recommended that the focus should be on legacy waste remediation.
Meanwhile, the Commission for Air Quality Management (CAQM) said in a statement that with the paddy harvesting season drawing to a close, Punjab and Haryana have recorded a significant decline in farm fires. Punjab recorded 5,114 fires this season, reflecting a reduction of 53% from 2024, 86% from 2023, 90% from 2022, and 93% from 2021. Likewise, Haryana logged 662 incidents, registering a 53% reduction from 2024, 71% from 2023, 81% from 2022, and 91% from 2021. The commission said, “These numbers represent the most significant decline achieved since CAQM began monitoring state-specific crop residue management measures.”
Sophiya Mathew is a Correspondent at The Indian Express, based in New Delhi. She joined the Delhi bureau in 2024, and has specialization in Integrated Multimedia Journalism from the Asian College of Journalism (ACJ), Chennai.
Professional Background
Core Beats: Her reporting is primarily focused on the Environment and Education.
Specialization: She has gained recognition for her ground-level reporting on the Yamuna floodplains and the socio-economic challenges faced by those living on its banks. She also focuses on the disparities in Delhi's education system, ranging from elite private schools to government institutions and refugee education.
Recent Notable Articles (December 2025)
Her recent work has been heavily centered on Delhi's severe winter pollution crisis and the government's regulatory responses:
1. The Air Pollution Crisis
"A tale of two cities: Delhi govt schools choke in bad air, private classrooms set up air filters" (Dec 20, 2025): A high-impact feature contrasting the "Clean Air Bubbles" in elite schools with the reality of government school students who are exposed to an equivalent of 17 cigarettes a day due to outdoor exposure.
"Delhi sees season's worst air day, second worst December AQI in nearly a decade" (Dec 15, 2025): An analytical report on the meteorological patterns trapping pollutants in the NCR.
"Delhi bans non-BS VI vehicles from outside: Why curbing vehicular pollution is key" (Dec 17, 2025): Explaining the science behind targeting specific vehicle vintages to lower particulate matter.
2. Enforcement & Regulations
"No fuel at pumps in Delhi without valid PUC certificate from December 18" (Dec 17, 2025): Breaking the news on the environment ministry's strict "No PUC, No Fuel" policy.
3. Education Policy
"Law to regulate school fee in Delhi risks becoming procedural, say parents" (Dec 13, 2025): Investigating the loopholes in the new Delhi School Education (Transparency in Fixation and Regulation of Fees) Bill, 2025.
"Monsoon Session: Private school fee regulation Bill cleared after four-hour debate" (Aug 9, 2025): Covering the legislative passage of the controversial fee hike regulation.
Signature Style
Sophiya is known for her observational depth. Her reporting often includes vivid details from school corridors, hospital waitlists, or the banks of the Yamuna to illustrate how policy failures affect the city's most vulnerable residents. She is a frequent expert guest on the 3 Things podcast, where she explains the complexities of Delhi’s environmental laws.
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