Pakistan emerged as the world’s most polluted country in 2025, with dangerous fine particle pollution (PM2.5) reaching levels up to 13 times higher than limits set by the World Health Organization, according to new data.
The findings come from an annual report by IQAir, which showed that only 13 countries and territories managed to keep average PM2.5 levels within the WHO guideline of less than 5 micrograms per cubic metre—an improvement from seven in 2024. Overall, however, 130 out of 143 monitored nations still failed to meet the recommended standard.
Bangladesh and Tajikistan ranked second and third among the most polluted countries, respectively. Meanwhile, Chad, which topped the list in 2024, slipped to fourth place—though researchers cautioned that this apparent improvement may reflect gaps in data rather than real progress.
The report highlighted how the shutdown of a key U.S. global air quality monitoring programme affected data reliability in several countries. According to lead author Christi Chester Schroeder, the loss of this data made it difficult to accurately assess pollution trends in some regions.
At the city level, Loni was identified as the most polluted urban area in 2025, followed by Hotan. Notably, all of the world’s 25 most polluted cities were located across India, Pakistan, and China.
Globally, only 14 percent of cities met WHO air quality standards in 2025, down from 17 percent a year earlier. Factors such as widespread wildfires in Canada contributed to rising pollution levels across United States and even parts of Europe.
Despite the overall trend, some countries showed improvement. Australia, Iceland, Estonia, and Panama were among those that met WHO standards. Meanwhile, Laos, Cambodia, and Indonesia recorded notable declines in pollution levels, largely due to wetter and windier La Niña conditions.
Overall, 75 countries saw an improvement in air quality compared to 2024, while 54 experienced worsening pollution levels, underscoring the uneven global progress in tackling air pollution.
