IQAir has announced the release of its 8th annual World Air Quality Report, offering a comprehensive analysis of global air pollution data from 2025 and highlighting persistent health risks, emerging regional trends and critical monitoring gaps worldwide.

For this year’s report, IQAir said it analyzed data from monitoring stations across 9,446 cities in 143 countries, regions and territories.

The report adds 12 countries and territories not included last year, seven of which appear in the dataset for the first time ever—marking continued expansion of global air quality monitoring coverage.

Comparing this year’s report to the previous 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.

Key findings from the 2025 World Air Quality Report published on the IQAir website:

Only 14% of global cities met the World Health Organization (WHO) annual PM2.5 guideline of 5 µg/m³, down from 17% the previous year. Only thirteen countries or territories met the WHO annual average PM2.5 guideline: French Polynesia, Puerto Rico, U.S. Virgin Islands, Barbados, New Caledonia, Iceland, Bermuda, Réunion, Andorra, Australia, Grenada, Panama, and Estonia. 130 out of 143 countries or territories, representing 91%, exceeded the WHO annual average PM2.5 guideline value.

The five most polluted countries were Pakistan with 67.3 µg/m³, Bangladesh with 66.1 µg/m³, Tajikistan with 57.3 µg/m³, Chad with 53.6 µg/m³, and the Democratic Republic of the Congo with 50.2 µg/m³. Loni, India, was the most polluted city, recording an annual average PM2.5 concentration of 112.5 µg/m³, which is a nearly 23% increase from 2024 and more than 22 times the WHO guideline. Nieuwoudtville, South Africa, was the world’s cleanest city, with an annual average PM2.5 concentration of 1.0 µg/m³.

The world’s 25 most polluted cities were all located in India, Pakistan, and China, with India home to three of the four most polluted. The most polluted major U.S. city was El Paso, Texas. Southeast Los Angeles, California, was the most polluted region in the United States. Seattle, Washington, was the cleanest major U.S. city.

The year 2025 marked the second consecutive year in which no cities in East Asia met WHO PM2.5 guidelines. Pollution patterns in China indicated a westward shift in elevated concentrations. Europe saw mixed air pollution trends in 2025, with 23 countries recording higher PM2.5 concentrations and 18 seeing declines. Winter wood burning, summer smoke from Canadian wildfires, and Saharan dust worsened seasonal pollution in Europe.

In Latin America and the Caribbean, air quality trends were largely positive. 208 cities recorded decreases in annual average PM2.5 concentrations, 95 cities saw increases, nine remained unchanged, and 13 new cities were added to the monitoring network. Oceania remained one of the world’s cleanest regions, with 61% of cities meeting the WHO guideline, although record-breaking cold in New South Wales, Australia, in June 2025 led to seasonal PM2.5 spikes.

According to the report, wildfires, intensified by climate change, played a major role in degrading global air quality in 2025. Record biomass emissions from Europe and Canada contributed to approximately 1,380 megatons of carbon. Canada was the most polluted country in Northern America for just the second time in this report’s eight-year history, as its second-worst wildfire season on record affected air quality across Canada, the United States and parts of Europe.

In the United States, annual average PM2.5 levels increased to 7.3 µg/m³. Smoke from wildfires in both Canada and the U.S. raised averages across parts of the Great Lakes states in the summer and in the Pacific Northwest in the fall.