Beyond BS-6: The Limits of Vehicle Bans in Solving Delhi’s Smog

Delhi’s air pollution crisis has continued well into late December 2025, with air quality remaining in the severe category across large parts of the city. According to data from the Central Pollution Control Board (CPCB) and advisories issued by the India Meteorological Department (IMD), the Air Quality Index (AQI) crossed 450 in areas such as Anand Vihar, Akshardham, and Ashok Vihar. Dense fog reduced visibility to near zero, disrupting flights and daily life. These conditions underline how meteorological factors, particularly winter fog, temperature inversion, and low wind speeds, trap pollutants close to the ground, worsening already high pollution levels.

While recent restrictions on non-BS6 vehicles aim to reduce vehicular emissions, their overall impact remains limited. Older, non-compliant vehicles contribute only about 4–6% of Delhi’s total PM2.5 pollution, even though they emit five to ten times more pollutants per vehicle compared to BS-6 compliant ones. As a result, banning these vehicles removes the dirtiest fraction of traffic emissions but addresses only a small portion of the city’s total pollution load. Even under strict enforcement, such measures result in only 10–13% targeted reductions when combined with GRAP Stage IV actions like water sprinkling, traffic curbs, and deployment of electric buses.

However, While BS-6 norms aim to reduce vehicular pollution, they also bring significant economic drawbacks. BS-6 vehicles are more expensive due to advanced emission-control technology, with petrol vehicles costing about 5–10% more and diesel vehicles 15–25% more than older models. For small traders, transporters, and daily-wage drivers, this makes replacement difficult. Maintenance costs are also higher, especially for BS-6 diesel vehicles that struggle in slow, congested traffic and require frequent servicing. Many BS-IV vehicles, still mechanically fit, have lost resale value, effectively turning them into stranded assets. Without subsidies or scrappage support, the transition risks placing a disproportionate financial burden on lower-income vehicle owners.

A broader look at Delhi’s pollution sources explains why air quality remains poor despite these steps. Road and construction dust account for the largest share, contributing 30–40% of pollution. This is followed by vehicular emissions (20–25%), stubble burning during winter peaks (20–30%), industrial emissions (10–15%), and waste burning (10–24%). Since non-BS6 vehicles form only a small slice of this mix, focusing heavily on them without equally strong action on dust control, regional crop burning, and industrial emissions limits the effectiveness of pollution control policies.

The limitations of current measures become clearer during extreme weather conditions. Although GRAP interventions can temporarily reduce AQI levels by 10–20%, winter fog, temperature inversions, and calm winds prevent dispersion of pollutants. As a result, December 2025 has been recorded as the worst December for air quality in the last eight years, with AQI consistently ranging between 350 and 460+. Enforcement gaps—estimated at 20–30% non-compliance—and pollution from neighbouring states further dilute the impact of city-level actions. IMD has repeatedly warned that such conditions could prolong severe air episodes.

A useful comparison can be drawn from Beijing’s pollution turnaround. Between 2013 and 2023, Beijing reduced PM2.5 levels by 50–60% through sustained, multi-year interventions. These included large-scale coal-to-gas transitions, the retirement of over 13 million polluting vehicles, strict industrial relocation, and legally binding regional cooperation agreements. Beijing’s experience shows that long-term investment, rather than seasonal emergency measures, is key to meaningful improvement.

For Delhi, this means scaling up its existing 25-point clean air plan into a year-round mission. Measures such as deploying 2,000+ mechanical road sprinklers daily, achieving the target of 10,000 electric buses by 2027, enforcing zero-stubble burning through cooperation with neighbouring states, and using AI-based pollution monitoring must be implemented consistently. Experts estimate that an annual investment of ₹5–10 billion (around 2–3% of GDP) would be required—an amount that could be recovered through ₹50,000 crore in health and productivity savings.

The economic argument strengthens the case for urgent action. Studies suggest that every rupee invested in clean air delivers a 7–10 times return, through reduced healthcare costs, increased worker productivity, job creation in green sectors, and 10–15% increases in property values. With flights grounded, schools disrupted, and public health at risk, piecemeal measures are no longer sufficient. Only sustained political will and coordinated action across all NCR states can offer Delhi a realistic path toward breathable air.

                          -The Civic Forum