Every breath matters. But for most people on earth, every breath also carries a hidden cost.
The IQAir 2025 World Air Quality Report, released this year by Swiss-based air quality technology company IQAir, paints a stark picture of a planet still struggling to clean up its act. Covering 9,446 cities across 143 countries, regions and territories , the most comprehensive dataset in the report’s history, it finds that only 14% of cities worldwide met the World Health Organisation’s annual air quality guideline for PM2.5 in 2025, down from 17% in 2024. PM2.5 refers to tiny particles in the air, smaller than the width of a human hair, that can enter the bloodstream and damage the heart, lungs and brain.
Just 13 countries met the WHO’s safe limit of 5 micrograms per cubic metre (µg/m³) for annual PM2.5 exposure. Most of them are in Latin America, the Caribbean and Oceania, regions that are, for now, among the world’s cleanest.
The overall picture worsened in 2025, driven in large part by a surge in wildfire activity in regions that have historically enjoyed relatively cleaner air. In Northern America, intense wildfires pushed Canada’s national average up 10% to 7.4 µg/m³, reclaiming its position as the most polluted country in the region. In Flin Flon, Manitoba, PM2.5 levels in June were nearly eight times higher than the same month in 2024, as fires crossed provincial borders and smoke blanketed entire states and provinces.
No region was immune. In Southeast Asia, the Philippines recorded a sharp 28% rise in pollution levels. In Europe, one of the most closely monitored regions on earth, only 5% of cities met the WHO guideline, with Switzerland and Greece each seeing national averages jump by more than 30%.
The crisis of dirty air is also about the years of life it quietly steals.
The Human Cost: What Dirty Air Does to the Body
The State of Global Air 2024 report, published by the Health Effects Institute, estimated that air pollution caused 8.1 million deaths globally in 2021, making it the second leading risk factor for death in the world, behind only high blood pressure. More than 700,000 of those who died were children under the age of five.
The damage begins before birth and compounds over a lifetime. Fine particles penetrate deep into the lungs, enter the bloodstream and reach every organ in the body. Long-term exposure causes heart disease, stroke, cancer, developmental delays in children and respiratory illness. The effects are cumulative and often irreversible.
For children in the world’s most polluted cities, the consequences are particularly severe. In South and Central Asia, the most polluted region on earth, cities like Dhaka, Delhi and Dushanbe each recorded at least two months in 2025 where PM2.5 concentrations surged above 100 µg/m³, twenty times the WHO’s safe limit.
The Most Polluted Region on Earth: Central and South Asia
Central and South Asia recorded the highest annual average PM2.5 concentrations of any region globally in 2025, a position it has held for years. Of the world’s 20 most polluted cities in 2025, 17 were located in this region.
Bangladesh, Pakistan and Tajikistan all recorded country-wide annual averages above 50 µg/m³, more than ten times the WHO guideline. The causes are well-documented: industrial and vehicle emissions, brick kilns, construction dust and the seasonal burning of crop residue after harvests. In East Asia, China recorded the region’s highest national average at 29.6 µg/m³, while its most polluted city, Hotan, reached a staggering 109.6 µg/m³.
Not a single city in East Asia, Southeast Asia or West Asia met the WHO annual guideline in 2025.
Africa’s Air Quality
Africa presents one of the most complex air quality stories in the 2025 report, a continent where progress is real, data is limited and the stakes could not be higher.
The report estimates that 330 million Sub-Saharan Africans live in areas where PM2.5 levels exceed 35 µg/m³, more than seven times the WHO safe limit. Chad recorded the continent’s highest national average at 53.6 µg/m³, followed by the Democratic Republic of Congo at 50.2 µg/m³ and Uganda at 43.0 µg/m³. Encouragingly, some cities are moving in the right direction: PM2.5 levels in Kinshasa dropped nearly 14% and Kigali saw an 8% reduction to 37.5 µg/m³.
Only 3% of African cities met the WHO annual guideline, though that figure represents an improvement, with the share of cities exceeding the guideline by five to seven times falling from 24% in 2024 to 9% in 2025.
The continent’s monitoring network, however, remains dangerously thin. Africa’s 463 air quality monitoring stations account for roughly 1% of the global total contributing to this year’s report. Without data, governments cannot act.
Ghana: Improvements Recorded, But the Work Has Barely Begun
Ghana ranked 11th most polluted country in Africa in 2025, with a national annual average PM2.5 concentration of 21.3 µg/m³, more than four times the WHO guideline. That figure, however, represents a significant drop from Ghana’s 2024 ranking of 8th most polluted on the continent, where it recorded 35.8 µg/m³.
The improvement is notable. But 21.3 µg/m³ still means that the average Ghanaian is breathing air that the WHO classifies as unhealthy on an annual basis. The familiar culprits, vehicle emissions from an ageing fleet, open burning of waste, industrial activity and domestic cooking with biomass, continue to drive pollution levels across the country’s urban centres.
There are reasons for cautious optimism. Ghana’s new Air Quality Management Regulation, highlighted in the report as a legal model for the continent, introduces mandatory reporting and a centralised data system, a framework that could, if enforced, transform how the country monitors and responds to its pollution crisis.
Where the Air Is Cleanest…
Oceania remained the world’s least polluted region in 2025. Australia improved slightly to 4.4 µg/m³ and the city of Papeete in French Polynesia recorded one of the world’s cleanest urban averages at just 1.5 µg/m³. In Latin America, Honduras made the year’s most dramatic national improvement, cutting its average by 59%, from 15.2 µg/m³ to 6.3 µg/m³, largely because the La Niña weather pattern brought increased rainfall that suppressed the wildfires that had driven up pollution during the El Niño years.
Every statistic in this report represents a life, a child coughing through the night, a grandmother whose heart disease was accelerated by decades of dirty air, a city whose residents have simply normalised breathing air that is slowly doing them harm. The data exists. The solutions exist. What remains to be written is whether the decisions will follow.
This story was a collaboration with New Narratives. Funding was provided by the Clean Air Fund which had no say in the story’s content.
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