Delhi's Decade-Long Struggle with Toxic Air
A comprehensive ten-year analysis has confirmed that New Delhi is the most polluted major city in India. The study, conducted by the environmental research group Climate Trends, examined air quality index (AQI) data from 2015 through November 2025 across eleven major urban centers. The findings paint a grim picture, revealing that not a single major Indian city managed to maintain safe air-quality levels at any point during this extensive period.
A Deep Dive into the Alarming Data
The Climate Trends assessment placed Delhi consistently at the top of the pollution chart, recording the highest AQI values nearly every year. The city's air pollution crisis reached its peak in 2016, with a mean AQI soaring to 256.3, which is classified as 'poor'. While there have been marginal improvements since 2019, the situation remains dire. This year, Delhi's AQI has hovered around 180, which is still the highest among all the cities surveyed, which included Bengaluru, Mumbai, Kolkata, Varanasi, Lucknow, and Pune.
In contrast, Bengaluru emerged as the cleanest of the major cities. However, even its air quality was far from safe, with AQI values mostly ranging between 65 and 90, levels that still exceed what is considered healthy.
The report identifies a complex mix of factors behind Delhi's persistently toxic air. These include emissions from dense traffic, industrial activity, winter temperature inversion, and the seasonal burning of crop residue. Compounding these issues is the city's unique local geography. Located on the Indo-Gangetic Plains, which stretch from Punjab to West Bengal, Delhi is part of a common airshed where pollutants become trapped, creating a persistent smog blanket.
Expert Insights and Regional Variations
Palak Balyan, the research lead at Climate Trends, emphasized that relocating is not a viable solution for most people. "Moving to another city for cleaner air isn't a real solution, and most people can't afford to do it anyway," Balyan stated. "What India needs is sustained, long-term and science-based policy reforms backed by genuine political will to take tough decisions."
Meteorologist Mahesh Palawat from Skymet Weather added that specific weather conditions have worsened the crisis this winter. The report notes that the Indo-Gangetic region received no rainfall from October 1 to November 28, removing a natural cleansing mechanism. Furthermore, weak western disturbances and strong, cold north-westerly winds have created a lid-like effect, preventing pollutants from dispersing and keeping them close to the ground.
Professor S N Tripathi from IIT Kanpur highlighted the critical need for reliable data to guide effective action. "There are numerous ways to be proactive, but we need an intelligent decision-support system to guide those choices," Tripathi said. He cautioned that poorly designed interventions can sometimes cause more pollution than they prevent and stressed the importance of using data to evaluate the real-time impact of any anti-pollution measure.
The report also outlined regional disparities. While north Indian cities like Lucknow, Varanasi, and Ahmedabad showed some improvement after 2020, their AQI levels continued to breach safe thresholds. Southern and western metros like Chennai and Mumbai demonstrated more pronounced improvement post-2020, yet they too failed to consistently achieve 'good' air quality.
