REUTERS, Singapore

Bangladesh was ranked the world’s smoggiest country in 2025, with concentrations of hazardous small particles known as PM2.5 up to 13 times higher than the recommended World Health Organization level, research showed yesterday.Pakistan topped the list, while Tajikistan ranked third among the most polluted countries.

Swiss air quality monitoring firm IQAir said in its annual report that 13 countries and territories kept average PM2.5 levels at the WHO standard of less than 5 microgrammes per cubic metre last year, up from seven in 2024.

However, 130 out of 143 monitored countries and territories failed to meet the WHO guideline.

India’s Loni was the world’s most polluted city in 2025, with average PM2.5 levels of 112.5 micrograms, followed by Hotan in the northwestern Chinese region of Xinjiang at 109.6 microgrammes.

The world’s top 25 most polluted cities were all in India, Pakistan and China.

Only 14 percent of the world’s cities met the WHO standard in 2025, down from 17 percent a year earlier, with Canadian wildfires driving up PM2.5 across the United States and as far as Europe.

Among the countries that met the standard in 2025 were Australia, Iceland, Estonia and Panama.

Laos, Cambodia and Indonesia all reported significant PM2.5 reductions compared to the previous year, thanks mainly to wetter and windier La Nina weather. Mongolia saw average concentrations fall 31% to 17.8 micrograms per cubic metre.

In all, 75 countries reported lower PM2.5 levels in 2025 compared to a year earlier, with 54 recording higher average concentrations, IQAir said.