- India’s overall air quality improved in 2025, ranking 6th globally.
- However, Loni in NCR emerged as the world’s most polluted city.
- Experts cite data gaps and local factors behind shifting ranki
Even as India's national PM 2.5 average levels recorded a marginal improvement, the National Capital Region (NCR) region continued to battle toxic levels of air, with Loni in Ghaziabad district ranked as the most polluted city in the world in 2025.
According to the 2025 World Quality Report by IQA, a Swiss air quality technology company, Loni recorded an abysmal annual average of 112.5 µg/m³ PM2.5 concentration. The report provides data on concentration of fine particulate matter (PM2.5), a major air pollutant, across the world.
In the survey for 2025, India emerged as the sixth most-polluted country in the world in terms of PM2.5 concentration levels.
India ranked as the third most polluted in 2023, while it was ranked fifth in 2024.
Delhi (99.6 µg/m³), Noida (80.5 µg/m³), Ghaziabad (89.2 µg/m³), Greater Noida (77.2 µg/m³) have been ranked among Central and South Asia region's top 15 polluted cities.
The data is sourced from 9,446 cities spanning 143 countries, regions, and territories and from more than 40,000 regulatory monitoring stations and low-cost sensors, managed by government agencies, universities, non-profit organisations, private enterprises and citizen scientists.
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While Delhi's yearly average improved by 8%, the city still witnessed hazardous monthly fluctuations. Air quality worsened significantly in December with a 44% increase in pollutants, while a major dust storm drove a 15% surge in April.
Why did Loni rank top in the list?
The air quality crisis is prompted by a mix of industrial negligence, dense traffic, and stubble burning. Poorly managed construction dust and waste combustion further worsen the situation. Because local weather patterns often trap these toxins near the surface, the city is stuck in a dangerous environmental loop that only large-scale policy shifts can resolve, say experts.
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Dr Gufran Beig, founder and project director of the System of Air Quality and Weather Forecasting and Research (SAFAR), cited by The Indian Express, explained that Loni emerged the most polluted possibly due to the availability of air quality data. “It is possible that in the next analysis, some other Indian city or any other in a different country would emerge at the top. It depends on the dense network of monitoring stations. Countries like Ghana won't find a ranking, though they might be polluted, just because they do not have a mechanism in place. Variations come because stations are coming up.”
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