Loni near Ghaziabad in the National Capital Region (NCR) is the world’s most polluted city, while Delhi fares worst among capital cities in the world, according to new data published by IQAir. This is for the eighth straight year that Delhi has retained the tag of being the world’s most polluted capital. As per IQAir’s World Air Quality Report 2025, Delhi recorded an annual PM2.5 concentration of 82.2 micrograms per cubic metre – nearly 16.4 times higher than the WHO’s safe limit of 5 micrograms per cubic metre. This also breached India’s own standard, set at 40 micrograms per cubic metre, by a wide margin.
The bigger picture is even more alarming. When the entire NCR is considered, Delhi’s annual PM2.5 average climbs to 99.6 micrograms per cubic metre, making it the fourth most polluted city globally. Loni – at the top of the list with 112.5 mcg per cubic metre – was followed by Hotan in China (109.6) and Byrnihat on the Meghalaya-Assam border (101.6).
And the problem is not confined to Delhi alone. The report, which analysed air quality across 9,446 cities in 143 countries, shows a cluster of cities in Delhi-NCR as pollution hotspots. Ghaziabad ranked 7th globally with PM2.5 levels of 89.2 micrograms per cubic metre, Noida 18th (80.5), Greater Noida 21st (77.2) while Gurgaon was ranked at 23rd (74.6).
Dip In Numbers But Spike In Pollution Levels
Even as Delhi’s annual average showed an 8% decline compared to 2024 – New Delhi had recorded 91.8 micrograms per cubic metre last year – experts warn against reading too much into the dip. “While Delhi’s annual average fell 8%, the city still saw sharp monthly spikes from seasonal smog and dust storms. A major April dust storm alone pushed PM2.5 up 15%. Winter pollution-driven by crop burning, temperature inversions, industry and construction – continued to plague the Indo-Gangetic plain,” the report said.
Manoj Kumar, an analyst at the Centre for Research on Energy and Clean Air, pointed to a critical gap in the current approach. “A significant share of particulate pollution is formed from gaseous pollutants. Unless the CAQM regulates these at the source, only part of the problem is being addressed,” he said.
IQAir global CEO Frank Hammes said there was need for sustained intervention. “Without monitoring, we cannot fully understand what we are breathing. Cutting emissions and addressing climate change are essential for lasting improvements in air quality,” he said.
Policy Failure Or Systemic Collapse?
Eight years at the top of a global pollution ranking is no longer a seasonal anomaly. It raises deeper questions about governance. The persistence of extreme pollution levels, despite measures such as GRAP restrictions and construction curbs, as well as anti-smog drives, shows a gap between policy, execution as well as on-ground impact.
Let’s not forget that the crisis may run deeper than policy failure.
Delhi’s air is shaped by a complex mix of regional and structural factors – crop burning across states, industrial emissions, vehicular load, construction dust, and meteorological conditions like winter inversions.
This makes the problem less about city’s governance and more about a multi-state system struggling to act in coordination.
The data points to a hard truth – that incremental measures are failing against a crisis that is structural. Unless emissions are tackled at source across the Indo-Gangetic plain, and unless institutions enforce accountability beyond city boundaries, the cycle is unlikey to break.
