Only seven countries managed to meet the World Health Organization's (WHO) air quality standards in 2024, a report revealed on Tuesday, highlighting worsening global air pollution and growing data gaps after the United States discontinued its international monitoring programme.

According to the annual report by Swiss air quality monitoring firm IQAir, Chad and Bangladesh ranked as the world’s most polluted countries, with average smog levels exceeding WHO’s recommended limit by more than 15 times.

Meanwhile, only Australia, New Zealand, the Bahamas, Barbados, Grenada, Estonia, and Iceland met the global air quality benchmark.

The report underscores significant data shortages, particularly in Asia and Africa, where many nations have relied on air quality sensors stationed at U.S. embassies and consulates. However, the U.S. State Department recently shut down the programme, citing budget constraints, and removed over 17 years’ worth of air quality data from its official monitoring site, airnow.gov.

The move is expected to severely impact air quality tracking, particularly in Africa, where real-time pollution data was largely dependent on the U.S. monitoring system. Christi Chester-Schroeder, IQAir’s air quality science manager, noted that many countries have alternative sources, but the loss would be acutely felt across the continent.

Chad, which was left out of IQAir’s 2023 report due to data concerns, returned as the most polluted country in 2024 with an average PM2.5 concentration of 91.8 micrograms per cubic meter (µg/m³), slightly higher than its 2022 level. The country’s pollution levels are exacerbated by Sahara Desert dust and widespread crop burning.

WHO recommends a PM2.5 concentration of no more than 5 µg/m³, but only 17% of global cities managed to stay within this limit last year.

South Asia remains a pollution hotspot

Pakistan ranked fourth on the list of the most polluted countries, trailing behind Chad, Bangladesh, and the Democratic Republic of Congo. India, which came in fifth, saw a 7% decline in its annual PM2.5 levels, but still recorded an average concentration of 50.6 µg/m³—ten times higher than WHO’s recommended limit.

Twelve of the world’s 20 most polluted cities were in India, with Byrnihat, a heavily industrialized town in the country’s northeast, emerging as the most polluted city with an average PM2.5 level of 128 µg/m³.

Experts warn that climate change is exacerbating air pollution worldwide, as rising temperatures contribute to prolonged and more intense wildfires. Forest fires in Southeast Asia and South America played a significant role in worsening air quality last year.

Christa Hasenkopf, director of the Clean Air Program at the University of Chicago’s Energy Policy Institute (EPIC), cautioned that the U.S. programme's closure would deprive at least 34 countries of reliable pollution data. She emphasized that the initiative had improved air quality in cities where monitors were installed, even reducing hazard allowances for U.S. diplomats stationed in highly polluted areas.

“The discontinuation of this programme is a major setback for global air quality efforts,” she said.