Heatwaves, wildfires and human-caused emissions combined this year to expose one third of the world’s population to extremely high levels of ozone pollution, a European Union report said last month.
In an analysis covering the first eight months of 2026, the Copernicus Atmosphere Monitoring Service (CAMS) – the European Union’s Earth observation programme – highlighted the close relationship between climate change and air pollution. When heat and sunlight react with airborne emissions from wildfires, vehicles and industry, they create ground-level ozone pollution (see graphic).
This damages lung tissue, causes breathing problems, triggers asthma attacks and leads to other health issues.
Despite progress in cutting the most harmful air pollutants in recent decades, ozone pollution has proved more difficult to tackle as climate change fuels the conditions that favour its formation.
This year’s ozone pollution was driven in part by record-breaking heatwaves and wildfires. These included ones that seared Europe and North America, sending smoke well beyond their borders, and more recent major blazes in Indonesia.
The warming El Nino weather pattern – which started in June and is due to peak later this year – could also contribute to more fires in Southeast Asia, according to the analysis.
“Air pollution does not stop at borders. It can travel thousands of kilometres, crossing continents and oceans and affecting air quality far from its source,” CAMS director Laurence Rouil said in the Atmosphere Watch report.
‘Extremely poor’ quality
CAMS uses satellite data and computer models to track air pollution and wildfires.
The report found that 34 per cent of the global population was exposed to “extremely poor” air quality between January 1 and September 15, meaning concentrations of ozone were well above the World Health Organization’s exposure guidance. Another 17 per cent of the world breathed “very poor” air.
Asia has the highest rate of exposure to ozone pollution, with 53 per cent of its population breathing “extremely poor” air. Another 22 per cent were exposed to “very poor” ozone.
The continent’s widespread emissions are driven by industrialisation, economic development and transport, as well as wildfires and the burning of agricultural residue.
New Delhi in India, Dhaka in Bangladesh, Chongqing in China and Lahore in Pakistan were among the Asian cities with “extremely poor” ozone.
Two thirds of the population in North America and 45 per cent in Europe were exposed to “poor” or “very poor” air quality. EU regulation has effectively reduced emissions from air pollutants, except for ozone, the report said.
Ozone pollution is linked to 60,000 premature deaths per year in Europe, Ian Marnane, an official at the European Environment Agency, told a media briefing.
Smoke from forest fires, crop burning and cooking are significant contributors to Africa’s air pollution, while Saharan dust travels as far as Europe. Eight per cent of Africa’s population endured “extremely poor” air quality this year. It was “very poor” or “poor” for 19 per cent.
Ozone pollution levels were very high in the Brazilian city of Sao Paulo and extremely elevated in Rio de Janeiro. Still, the air quality was “good” or “fair” for 81 per cent of South America’s population.
One bright spot was Oceania – including Australia and New Zealand – where 66 per cent of the population enjoyed “good” ozone levels and 34 per cent lived under “fair” conditions.
How is air quality measured?
Air quality tells us how clean or polluted the air outside is. It is tracked using the Air Quality Index (AQI). The AQI has a range of values between 0 and 500 and uses six colour-coded categories.
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Green and yellow (0-100): Air quality is acceptable and safe for most people.
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Orange (101-150): Air quality is unhealthy for sensitive individuals, including children, older adults and people with heart or lung conditions.
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Red and purple (151-300): Air quality is unhealthy to very unhealthy for everyone, including vulnerable groups.
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Maroon (301-500): Air quality reaches hazardous emergency levels, posing serious health risks to the entire population.
