Bangladesh, Pakistan, India rank worst for smog: Report

Chad and Bangladesh were the world’s most polluted countries in 2024, with average smog levels more than 15 times higher than World Health Organization (WHO) guidelines, according to figures compiled by Swiss air quality monitoring firm IQAir.

India ranked fifth in smog levels behind Chad, Bangladesh, Pakistan, and the Democratic Republic of Congo. The country saw a 7% drop in average PM2.5 levels, reaching 50.6 micrograms per cubic meter. However, India accounted for 12 of the 20 most polluted cities. Byrnihat, an industrial hub in the country’s northeast, topped the list with an average PM2.5 level of 128 micrograms per cubic meter.

Climate change is playing an increasing role in worsening pollution, said IQAir’s air quality science manager, Christi Chester-Schroeder, with rising temperatures fueling more intense and prolonged wildfires across parts of Southeast Asia and South America.

Only 17% of cities meet WHO standards

Only seven countries met WHO air quality standards in 2024, IQAir said Tuesday. Australia, New Zealand, the Bahamas, Barbados, Grenada, Estonia, and Iceland were the only nations to comply with the recommended PM2.5 limit of 5 micrograms per cubic meter.

Significant data gaps, especially in Asia and Africa, obscure the global pollution picture. Many developing nations relied on air quality sensors at U.S. embassies and consulates to track smog levels. However, the U.S. State Department recently ended the program due to budget constraints, removing 17 years of data from its official air quality monitoring site, airnow.gov. The move included removing readings collected in Chad.

“Most countries have a few other data sources, but it's going to impact Africa significantly because oftentimes these are the only sources of publicly available real-time air quality monitoring data,” Chester-Schroeder said.

Chad was left off IQAir’s 2023 list due to data concerns, but it ranked as the world’s most polluted country in 2022. The nation’s air quality is heavily impacted by Sahara dust and uncontrolled crop burning. Last year, its PM2.5 concentration averaged 91.8 micrograms per cubic meter, slightly higher than in 2022.

End of US program a ‘blow’ to global efforts

At least 34 countries will lose access to reliable pollution data following the U.S. program’s closure, said Christa Hasenkopf, director of the Clean Air Program at the University of Chicago’s Energy Policy Institute.

The U.S. State Department's monitoring efforts helped improve air quality in cities where the sensors were placed, increasing life expectancy and even reducing hazard allowances for U.S. diplomats, which made the program cost-effective, Hasenkopf said.

“The end of the program is a giant blow to air quality efforts worldwide,” she said.