Only 14% of the world’s cities met international air quality standards in 2025, down from 17% a year earlier, as worsening pollution pushed Pakistan to the top of the global rankings for hazardous air exposure, according to new research released on Tuesday.
Pakistan was ranked the world’s most polluted country in 2025, with concentrations of fine particulate matter, known as PM2.5, reaching levels up to 13 times higher than the safety threshold set by the World Health Organization (WHO), Swiss air quality monitoring firm IQAir said in its annual report.
PM2.5 particles are among the most dangerous air pollutants, capable of penetrating deep into the lungs and bloodstream, increasing the risk of respiratory and cardiovascular diseases.
Global Findings
The report found that 130 of 143 monitored countries and territories failed to meet the WHO’s recommended annual PM2.5 limit of less than 5 micrograms per cubic metre.
Only 13 countries and territories recorded air quality within the guideline in 2025, up from seven in 2024. These included Australia, Iceland, Estonia and Panama.
After Pakistan, Bangladesh and Tajikistan ranked second and third on the list of the most polluted countries.
Chad, which was the world’s most polluted country in 2024, fell to fourth place in 2025. However, researchers cautioned that the apparent improvement was likely due to data gaps, rather than a real reduction in pollution.
Data Gaps and Monitoring Cuts
The report highlighted the impact of the United States’ decision last March to shut down a global air monitoring programme that relied on pollution data from U.S. embassies and consulates, citing budget constraints.
“The loss of the data made it appear there was a significant drop in PM2.5 levels in some countries, but the fact is that we don’t know,” said Christi Chester Schroeder, lead author of the IQAir report.
As a result, countries including Burundi, Turkmenistan and Togo were excluded from the 2025 assessment due to insufficient data.
Most Polluted Cities
India’s Loni was identified as the world’s most polluted city in 2025, with average PM2.5 levels of 112.5 micrograms per cubic metre. It was followed by Hotan in China’s Xinjiang region, which recorded levels of 109.6 micrograms.
The report noted that the 25 most polluted cities globally were all located in India, Pakistan and China.
Climate and Regional Trends
Air quality deteriorated in several regions in 2025, partly due to Canadian wildfires, which pushed PM2.5 levels higher across the United States and even parts of Europe.
At the same time, several Southeast Asian countries, including Laos, Cambodia and Indonesia, recorded significant improvements, largely due to wetter and windier La Niña weather conditions.
Mongolia saw one of the sharpest improvements, with average PM2.5 levels falling 31% to 17.8 micrograms per cubic metre.
Overall, 75 countries reported lower PM2.5 levels in 2025 compared with the previous year, while 54 countries recorded worsening air quality, IQAir said.
