Heatwaves, wildfires and human-caused emissions exposed a third of the world’s population to extremely high ozone pollution in 2026, with Asia worst hit and wildfire smoke crossing oceans, an EU report said on Wednesday.
Some 34 percent of people worldwide faced "extremely poor" air quality between 1 January and 15 September, the EU's Copernicus Atmosphere Monitoring Service (CAMS) found in its first Atmosphere Watch review.
CAMS tracks air pollution and wildfires using satellite data and computer models. An "extremely poor" rating means ozone concentrations were well above the World Health Organization (WHO) guideline of 100 micrograms per cubic metre, averaged over eight hours.
Another 17 percent of the world's population breathed "very poor" air, while just 5 percent enjoyed "good" conditions.
Pollution without borders
Ground-level ozone forms when heat and sunlight react with pollution from sources including vehicles, industry and wildfires.
Unlike ozone high in the atmosphere, which protects life from harmful ultraviolet radiation, ozone near the ground can damage lung tissue, cause breathing problems and trigger asthma attacks.
This year's ozone pollution was driven partly by record-breaking heatwaves and wildfires across Europe and North America.
Smoke from some North American fires crossed the Atlantic and reached Europe, while Saharan dust repeatedly travelled into southern Europe and across the North Atlantic.
"Air pollution does not stop at borders," warned CAMS director Laurence Rouil. "It can travel thousands of kilometres, crossing continents and oceans and affecting air quality far from its source."
Despite progress in cutting some of the most harmful air pollutants in recent decades, ozone has proved harder to tackle as climate change fuels the conditions that help it form.
Asia bears the brunt
Asia had the highest exposure, with 53 percent of its population breathing "extremely poor" air and another 22 percent "very poor" air.
India's New Delhi, Bangladesh's Dhaka, China's Chongqing and Pakistan's Lahore were among cities with "extremely poor" ozone levels. Industrialisation, economic development and transport, as well as wildfires and the burning of crop waste, contributed to emissions across the continent.
Two thirds of people in North America and 45 percent of Europeans were exposed to "poor" or "very poor" air quality.
Ozone pollution is linked to 60,000 early deaths each year in Europe, Ian Marnane, head of environment and health at the European Environment Agency, told journalists.
"Air pollution is one of the biggest environmental risks to health in Europe, linked to heart disease, stroke, lung cancer and respiratory illness," said Dorota Jarosinska, programme manager at the WHO European Centre for Environment, Climate Change and Health.
Sharp regional contrasts
Smoke from forest fires, crop burning and cooking is a major source of air pollution in Africa. Some 8 percent of Africans endured "extremely poor" air quality, while 19 percent breathed air rated "very poor" or "poor".
Ozone concentrations were very high in Brazil's Sao Paulo and extremely high in Rio de Janeiro – although 81 percent of South Americans breathed "good" or "fair" air.
Oceania, including Australia and New Zealand, was a bright spot, with 66 percent of its population enjoying "good" ozone levels and the remaining 34 percent living under "fair" conditions.
(with newswires)
