India’s biggest cities have endured a decade of unhealthy to hazardous air, with none meeting safe Air Quality Index (AQI) standards between 2015 and November 2025, according to a new analysis by Climate Trends, a New Delhi-based Organisation.
Drawing on long-term data from the Central Pollution Control Board (CPCB), the report reveals deeply entrenched pollution trends, severe deterioration in northern cities, and the escalating impact of winter meteorology on air stagnation.
The study compared mean AQI values across 11 major cities, including Delhi, Bengaluru, Mumbai, Chennai, Varanasi, Lucknow, Ahmedabad, Pune, Visakhapatnam, Kolkata, and Chandigarh. It concludes that “none of the top urban centres in India can be considered safe in terms of air quality”, despite improvements in select cities after 2020.
Delhi remained the most polluted city across the entire assessment period, with AQI levels peaking above 250 in 2016 and stabilising around 180 in 2025, far beyond acceptable limits. The report attributes this to a combination of vehicular emissions, industrial activity, winter inversion, and crop-burning impacts.
Although the capital saw a minor decline in pollution after 2019, the city “never approaches safe thresholds and continues to experience chronic poor air quality.”
The charts illustrate how Delhi consistently surpasses all other cities year after year.
Lucknow, Varanasi and Ahmedabad also exhibit persistently high AQI values. Lucknow and Varanasi frequently registered levels above 200 until 2020, while Ahmedabad fluctuated between 110 and 160, with only modest improvement after 2017. Even Varanasi’s recent gains have not pushed it into the “safe” category.
These cities lie in the Indo-Gangetic Plains, a region the report describes as a “meteorological trap”, where winter inversion, cold north-westerly winds and the Himalayan topography combine to lock pollutants close to the ground.
Chennai, Mumbai, Visakhapatnam, Kolkata, and Chandigarh show moderate AQI values, mostly ranging between 80 and 140, with some encouraging declines post-2020.
Chennai and Mumbai in particular improved in 2024–25, likely reflecting cleaner fuels, emission norms, and a slowdown during pandemic years. However, the report stresses that even these gains fall short of safe benchmarks.
Bengaluru recorded the lowest AQI among all cities, mostly between 65 and 90, yet still above the “Good” category. Rapid urbanisation, traffic density, and construction are keeping pollution levels from dropping further, the document notes.
One of the most striking findings is that Delhi’s air quality did not improve in late 2025 despite a “massive decrease” in farm fires, revealing the overpowering role of meteorology.
The absence of rain from October 1 to November 28 — combined with weak Western Disturbances —prevented natural pollutant washout.
“With cold north-westerly winds sweeping into the plains, minimum temperatures are set to drop further — making it even harder for pollutants to disperse... Without rain to wash pollutants out of the atmosphere, the pollution lingers for longer periods, leading to early and persistent smog-like conditions,” said Mahesh Palawat, vice president, meteorology and climate change, Skymet Weather.
The report explains how winter inversion creates an atmospheric “lid,” trapping cool air below warm layers and restricting vertical mixing. Combined with the Himalayas blocking airflow to the north, pollutants accumulate through December and January.
The study emphasises the need for proactive, technology-driven pollution control rather than reactive responses.
“Technology can help address many local pollution sources within your own airshed, but this requires reliable data…We need an intelligent decision-support system to guide choices, whether it’s assessing if an anti-smog gun is effective, cost-efficient, or even necessary,” said Prof SN Tripathi, dean, Kotak School of Sustainability at IIT-Kanpur.
He warned that poorly designed interventions can worsen the situation, making real-time evaluation crucial.
Highlighting the socio-economic dimension of India’s air crisis, Palak Balyan, research lead at Climate Trends, said: “Moving to another city for cleaner air isn’t a real solution…people who spend more time outdoors, like street vendors, sanitation staff, transport workers and construction workers, feel the impact the most. Over time, pollution also influences the quality of life, productivity, and economic well-being. Instead of short-term fixes…investing in systemic change is the only way to truly tackle the country’s pollution crisis.”
The report’s 10-year dataset leads to a stark conclusion: no Indian metro currently provides safe air for its residents. Pollution is driven by traffic, industrial activity, construction, regional emissions, and unfavourable winter meteorology—pressures that span geography and governance.