About one-third of the world’s population was exposed to extremely poor ozone air quality during the first eight months of 2026, driven by heatwaves, wildfires and human-caused emissions, according to a European Union report.

The analysis by the EU’s Copernicus Atmosphere Monitoring Service (CAMS), covering Jan 1 to Sept 15, highlights the growing link between climate change and air pollution.

Ground-level ozone forms when heat and sunlight react with pollutants released by wildfires, vehicles and industrial activity. It can damage lung tissue, cause breathing difficulties and trigger asthma attacks.

The report said 34% of the global population was exposed to “extremely poor” air quality, with ozone concentrations significantly exceeding the World Health Organization’s recommended exposure level.

Another 17% experienced “very poor” ozone levels, while only 5% of the global population was exposed to “good” ozone levels.

Asia recorded the highest exposure, with 53% of its population breathing air classified as “extremely poor” for ozone and another 22% exposed to “very poor” levels.

New Delhi, Dhaka, China’s Chongqing and Pakistan’s Lahore were among the cities where ozone levels were classified as “extremely poor”.

The report attributed high ozone levels in Asia to industrialisation, economic development, transport, wildfires and agricultural residue burning.

“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,” said CAMS Director Laurence Rouil.

Heatwaves, wildfires worsen pollution

Record-breaking heatwaves and wildfires in Europe and North America contributed to this year’s high ozone levels, with smoke travelling far beyond the areas where fires originated.

Indonesia also experienced major wildfires, while the warming El Nino weather pattern, which began in June and is expected to peak later this year, could increase fire risks in Southeast Asia, according to the report.

Despite significant progress in reducing several harmful air pollutants over recent decades, ozone has proved more difficult to control as rising temperatures create conditions favourable for its formation.

In Europe, 45% of the population was exposed to “poor” or “very poor” ozone levels. Ozone pollution is associated with around 60,000 premature deaths a year in Europe, according to Ian Marnane of the European Environment Agency.

In North America, two-thirds of the population experienced “poor” or “very poor” air quality. Ozone levels there remained “relatively unchanged” despite emissions reduction policies, the report said.

Africa saw 8% of its population exposed to “extremely poor” ozone levels, while 19% experienced “very poor” or “poor” conditions. Forest fires, crop burning and cooking emissions were identified as major contributors, while Saharan dust can travel as far as Europe.

In South America, ozone levels were very high in Sao Paulo and extremely elevated in Rio de Janeiro, although 81% of the continent’s population experienced “good” or “fair” ozone conditions.

Oceania recorded the lowest levels of exposure, with 66% of people in Australia and New Zealand experiencing “good” ozone levels and the remaining 34% living under “fair” conditions.