A decade after the Centre launched its National Clean Air Programme, a new analysis of air quality data from 2015 till 2025 has delivered a stark verdict: not a single major Indian city has breathed truly safe air in the past ten years.
The most striking revelation from non-governmental organisation Climate Trends' long-term study across 11 metros is that even Bengaluru, long celebrated as India's cleanest big city, has never once recorded an annual average in the "good" category. Its AQI has hovered stubbornly between 65 and 90 for the entire period, always above the safe threshold of 50. In practical terms, that means even India's "greenest" metropolis has exposed its residents to unhealthy air every single day for ten straight years.
Delhi remains the national capital of toxic air. Despite cloud seeding, a push for cleaner fuels, electric buses, and countless emergency action plans, the city's annual average AQI still lingers around 180 in 2025, barely better than the nightmare peaks above 250 recorded in 2016. This year offered a natural experiment: farm-fire incidents in Punjab and Haryana plummeted, yet Delhi's winter smog arrived earlier and thicker than ever. The reason, meteorologists say, is simple and terrifying. Zero rainfall since 1 October, unusually weak Western Disturbances, and a thickening temperature inversion have turned the Indo-Gangetic plain into a giant atmospheric trap. Pollutants have nowhere to go; the Himalayas block escape to the north, slow north-westerly winds crawl across the plains, and cold, heavy air pins the polluted air close to the ground.
The story repeats across the north. Lucknow and Varanasi, which routinely crossed 200 in the late 2010s, have improved since 2020 but still breathe air that would be classified "unhealthy" in most countries. Ahmedabad, Kolkata, Mumbai, Chennai, Chandigarh, and Visakhapatnam all show the same pattern: moderate but never safe, with occasional dips that tease hope before the next spike erases the gains.
Local sources (vehicles, construction dust, roadside cooking, small industries) now dominate more than episodic villains like crop burning. When winter meteorology aligns against the region, as it has in 2025, even dramatic reductions in one pollution source cannot clear the sky. "We are fighting physics as much as emissions," says Mahesh Palawat of Skymet Weather, pointing to the inversion layer that acts like a lid on a pressure cooker.
For millions of street vendors, traffic police, delivery workers, and construction labourers who spend their days outside, the consequences are measured in shortened lives and hospital visits. Researchers warn that moving to another Indian city is no escape as the entire urban map is shaded in varying degrees of red and orange.
