Bangladesh has topped the list of the world’s most polluted countries in 2024, according to the latest report by IQAir, a Switzerland-based air quality monitoring organization.

Chad, an African nation, shares the top spot with Bangladesh, both recording alarming levels of air pollution.

The report, released on Tuesday, reveals that Bangladesh’s average air pollution level was 15 times higher than the World Health Organization’s (WHO) recommended limit. Chad, India, Pakistan, and the Democratic Republic of Congo also featured prominently on the list of countries with dangerously high pollution levels.

IQAir’s data indicates that only seven countries met the WHO’s air quality standards in 2023: Australia, New Zealand, the Bahamas, Barbados, Grenada, Estonia, and Iceland. Researchers have warned that the fight against air pollution could become even more challenging after the United States discontinued its global air quality monitoring program.

Reuters reported that the absence of U.S. monitoring has created a significant gap in air quality data, particularly in Asia and Africa. Many developing countries relied on air quality sensors installed at U.S. embassies and consulates for accurate pollution data.

However, due to budget constraints, the U.S. State Department recently shut down this program, removing over 17 years of air quality data from its public website, including information on Chad.

Christi Chester-Schroeder, Air Quality Science Manager at IQAir, expressed concern, stating, “While most countries have some alternative data sources, Africa will be particularly affected. In many cases, the U.S. website was the only source of air quality monitoring data.”

Chad, which was excluded from the 2023 list due to data limitations, was previously identified as the world’s most polluted country in 2022. Factors such as Saharan dust and uncontrolled crop burning contributed to its high pollution levels. In 2024, Chad’s average level of PM2.5—tiny, hazardous airborne particles—was recorded at 91.8 micrograms per cubic meter, slightly higher than in 2022.

According to WHO guidelines, the annual average PM2.5 concentration should not exceed 5 micrograms per cubic meter. However, Bangladesh and Chad far exceeded this limit, with India, Pakistan, and the Democratic Republic of Congo also ranking among the most polluted nations.

India, which ranked fifth on the list, saw a 7% reduction in its average PM2.5 levels, dropping to 50.6 micrograms per cubic meter. Despite this improvement, 12 of the world’s 20 most polluted cities are in India, with Bhiwadi, an industrial city in the northeast, recording the highest levels at 128 micrograms per cubic meter.

Chester-Schroeder warned that climate change is exacerbating air pollution, with rising temperatures leading to more frequent and severe wildfires in Southeast Asia and South America. These wildfires are significantly contributing to deteriorating air quality.

Christa Hasenkopf, Director of the Clean Air Program at the University of Chicago’s Energy Policy Institute (EPIC), highlighted the impact of the U.S. discontinuing its monitoring program. She noted that at least 34 countries will lose access to reliable air pollution data, which has previously helped improve life expectancy and reduce health risks for diplomats and local populations.

Hasenkopf described the shutdown as a “major blow” to global air quality monitoring efforts. She emphasized that the U.S. program not only served global interests but also benefited the U.S. by reducing health risks for its personnel abroad.