NO₂ to CO: Toxic vehicle emissions spiking in early winter, says CSE study

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.

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.”