Loni, a town near Ghaziabad in Uttar Pradesh and bordering northeast Delhi, has been ranked the most polluted city globally for 2025, according to the latest World Air Quality Report released by Swiss air quality technology firm IQAir on Tuesday.
The report, which aggregates data from over 80,000 monitoring points across approximately 10,000 cities in 143 countries, recorded Loni's annual average concentration of fine particulate matter (PM2.5) at 112.5 micrograms per cubic metre. This marks a sharp, nearly 23% increase from 2024 levels and exceeds the World Health Organisation's (WHO) annual guideline of 5 micrograms per cubic metre by more than 22 times.
PM2.5 particles, small enough to penetrate deep into the lungs and enter the bloodstream, are linked to severe health risks, including respiratory diseases, cardiovascular problems, stroke, lung cancer, and premature death. Residents of Loni and surrounding areas face heightened exposure, particularly during peak pollution months.
Top Polluted Cities and India's Dominance
Three Indian cities claimed spots among the world's four most polluted in 2025:
- Loni, India - 112.5
- Hotan, China - 109.6
- Byrnihat, Meghalaya, India - 101.1
- New Delhi, India - 99.6 (down about 8% from the previous year but still the world's most polluted capital for the seventh time in eight years)
(All values in micrograms per cubic metre)
Five Indian cities featured in the global top 10, with Ghaziabad (Uttar Pradesh) at seventh and Ula (Birnagar) in West Bengal at tenth. The top 25 most polluted cities were concentrated in India, Pakistan, and China. Only 14 per cent of monitored cities worldwide met the WHO's safe PM2.5 guideline in 2025, down from 17 per cent the year before.
At the country level, Pakistan ranked as the world's most polluted nation, followed by Bangladesh and Tajikistan. India placed sixth, highlighting persistent air quality challenges across South Asia.
Factors Driving Loni's Spike
The report attributes Loni's worsening pollution to a combination of chronic sources and extreme events. A massive dust storm in April caused regional spikes, while December saw PM2.5 levels surge by an average of 62% in Uttar Pradesh cities, including Loni, amid stagnant winter weather that traps pollutants. Key contributors include:
- Vehicular emissions and industrial activity in the densely populated National Capital Region (NCR).
- Crop residue burning in nearby agricultural areas.
- Construction dust, road dust, and power generation emissions.
- Seasonal meteorological conditions, such as low wind speeds and temperature inversions in winter.
Loni, part of the Ghaziabad district, has long struggled with poor air quality due to its proximity to Delhi's pollution plume and local sources like brick kilns and small industries.
Health and Environmental Implications
Experts warn that prolonged exposure at these levels constitutes a public health emergency. Children, the elderly, and those with pre-existing conditions are especially vulnerable. Studies link high PM2.5 to reduced life expectancy, cognitive impacts, and increased healthcare burdens.
Globally, air pollution remains one of the largest environmental risk factors for premature death. The IQAir report reveals that progress is uneven: while some cities improved slightly, overall compliance with WHO standards declined, exacerbated by events like Canadian wildfires affecting distant regions.
Calls For Action
Environmentalists and public health advocates are urging stronger enforcement of emission norms, promotion of clean energy, better waste management (including stubble burning alternatives), and expanded monitoring networks. India's National Clean Air Programme has aimed to reduce pollution in non-attainment cities, but critics say implementation needs acceleration, especially in the Indo-Gangetic Plain.
