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Bengaluru: India is the sixth most-polluted country when it comes to levels of fine particulate matter, a major air pollutant, as per the 2025 World Air Quality Report by IQAIR, a Swiss air quality technology company.

Weighted by population, India’s average concentration of fine particulate matter (PM2.5) measured in micrograms per cubic meter (µg/m³), in 2025 was 48.9 (it was 50.6 in 2024). The World Health Organisation’s (WHO’s) recommended annual guideline level is 5 µg/m³. This small decline in PM2.5 levels, however, is not “statistically significant”, the lead author of the report told The Wire.

India is still home to the most polluted city in the world: in 2025, it was Loni in Ghaziabad, recording an annual average PM2.5 concentration of 112.5 µg/m³, which is more than 22 times the WHO permissible guidelines. Among capital cities across the world, India’s New Delhi ranked as the most polluted capital, with an average PM2.5 concentration of 82.2 µg/m³.

Global trends: India home to most polluted city

The 2025 IQAir World Air Quality Report provides data on concentration of fine particulate matter (PM2.5) across the world. The data is sourced from 9,446 cities spanning 143 countries, regions, and territories (when compared to 8,954 cities in 138 nations last year) 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. 

Globally, only 13 countries, regions and territories saw annual average PM2.5 concentrations meeting the WHO annual PM2.5 guideline of 5 μg/m³, with the majority located in the Latin America and Caribbean region. 

According to the report, Central and South Asia continue to experience the highest annual average PM2.5 concentrations globally, with 17 of the world’s 20 most polluted cities in 2025 being located in this region. “Of the 358 cities across 10 regional countries included in the 2025 Report, 71 cities reported annual average concentrations exceeding 50 µg/m³, more than ten times the current WHO guideline,” the report noted. 

Loni in Ghaziabad in India was the most polluted city, recording an annual average PM2.5 concentration of 112.5 µg/m³ – a nearly 23% increase from 2024 and more than 22 times the WHO guideline, per the report. The cleanest city, meanwhile, was Nieuwoudtville in South Africa, with an annual average PM2.5 concentration of just 1.0 µg/m³.

Compared to last year, 54 countries experienced increases in annual average PM2.5, 75 saw declines, two remained unchanged and 12 were newly represented in this year’s dataset, the report said.

“Air quality is a fragile asset that requires active stewardship to........

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