Ground-Level Ozone Exposed Nearly 40% of the World to Dangerous Air in 2026, Copernicus Finds — Asia Hit Hardest

Nearly 40 per cent of the world's population was exposed to dangerous levels of ground-level ozone during the first eight months of 2026, according to a global analysis by the Copernicus Atmosphere Monitoring Service (CAMS), with Asia bearing the heaviest burden and only a small fraction of people breathing air rated "good" for ozone.

The findings, published in CAMS's inaugural Atmosphere Watch report on 30 September 2026 and highlighted again in coverage on 2 November 2026, describe an "ozone-climate penalty": extreme heat combined with human-caused emissions to push a lesser-discussed pollutant to harmful levels across much of the Northern Hemisphere. CAMS is operated by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission, and its analysis combines satellite observations, ground-based networks, aircraft data and atmospheric modelling.

Asia was the region most affected, CAMS reported, followed by Europe and North America. In Asia, about 60 per cent of the population was exposed to extremely high ozone levels, rising to about 90 per cent when people exposed to "poor" and "very poor" levels are also counted, according to the CAMS summary. Only about 5 per cent of the world's population was exposed to ozone levels rated "good" under World Health Organization (WHO) guidelines, CAMS said.

Illustration: A city skyline under a hazy, heat-tinted sky, symbolising ground-level ozone smog — an illustration, not a photograph of any real place or event.

What Happened

CAMS released Atmosphere Watch as a new global snapshot of transboundary air pollution, covering ozone, wildfire smoke and desert dust during the first eight months of 2026, from 1 January to mid-September. The ozone chapter found that exposure was "extremely high and persistent" across Asia, while several days of very high exposure were also observed in Europe and North America amid frequent summer heatwaves, according to the CAMS ozone page.

The headline figure — nearly 40 per cent of the global population exposed to extremely high ozone — refers to the peak-season average: the highest daily eight-hour average ozone concentration, averaged over the six worst months, CAMS explained. The WHO recommends keeping peak-season ozone below 60 micrograms per cubic metre; CAMS rates air above 110 micrograms per cubic metre as "extremely poor". By that measure, roughly half of the world's population was exposed to "very" or "extremely" poor air quality from ozone in 2026, CAMS reported.

Regional patterns were stark. Oceania was the cleanest region in the analysis, with its entire population experiencing "good" or "fair" ozone levels, according to both CAMS and the 2 November coverage by Indonesia Now. In South America, more than 81 per cent of the population enjoyed air considered good or acceptable, a status shared by 56 per cent of the population in Africa, Indonesia Now reported. In North America and Europe, Indonesia Now's summary put the share of people exposed to high ozone concentrations at about two-thirds and about half respectively — figures that reflect that outlet's summary of the report rather than a single CAMS headline number, and they are reported here on that basis.

Some of the highest city-level exposures identified by CAMS were in Rio de Janeiro, Mexico City, Milan, Delhi and Cairo, the CAMS ozone chapter said. The report does not count deaths attributable to ozone in 2026, and its exposure figures are model estimates matched to population maps, not a monitor outside every home — a caveat reported by Earth.com in its summary of the findings.

Background

Ground-level, or tropospheric, ozone is not emitted directly. It forms near the Earth's surface when pollutants from transport, industry and other human activity react in sunlight and high temperatures — which is why heatwaves make it worse. That is different from the ozone layer high in the stratosphere, which protects life from ultraviolet radiation; at ground level, ozone is a harmful secondary pollutant that can damage human health and ecosystems and reduce agricultural yields, CAMS said.

CAMS director Laurence Rouil was quoted in the coverage as saying ozone pollution shows how the atmosphere, climate, health and livelihoods are connected. The report also pointed to smoke from significant fires and severe dust transport as other key hazards in 2026, and noted that air pollution repeatedly crossed borders and continents during the year — meaning emissions in one place can worsen air quality far away.

The Indonesian coverage on 2 November added a local illustration of that interconnected picture. It pointed to NASA satellite visualisations showing elevated carbon monoxide across Indonesia's major islands, and to the national Meteorology, Climatology, and Geophysics Agency (BMKG) tracking smoke distribution and hundreds of active hotspots. Carbon monoxide is a different pollutant from ozone, and the article itself cautioned that high-altitude pollutant layers do not automatically mean surface-level danger everywhere — but it argued that transported haze, vehicle exhaust and industrial emissions together compound air-quality challenges in cities such as Greater Jakarta.

Illustration: A satellite monitoring atmospheric pollution above Earth, symbolising global air-quality observation — an illustration, not a photograph of any real satellite or event.

Why It Matters

Ozone matters for three connected reasons: health, food and the climate itself. As a respiratory irritant, ground-level ozone can aggravate breathing problems, particularly during heatwaves when people are already under heat stress. For ecosystems and farming, it can damage plants and cut yields — a cost that falls on the same regions already facing heat and water stress. And because ozone formation rises with temperature, a warming climate can make ozone pollution worse even if precursor emissions stay flat, creating a feedback that CAMS calls the "ozone-climate penalty".

The report's timing adds weight to that message. It lands just one week before the COP31 climate conference in Antalya, Türkiye, which runs from 9 to 20 November 2026, with a World Leaders' Summit scheduled for 11–12 November. COP31 is expected to focus on implementing existing climate commitments, including energy transition and climate finance, rather than negotiating an entirely new framework. Ozone is not itself a COP negotiating item in the way carbon dioxide is, but the same emission cuts that reduce greenhouse gases — from transport, industry and energy — also cut the precursors that form ozone, so climate policy and air-quality policy pull in the same direction.

The geographic imbalance matters too. Asia's exposure reflects industrialisation, urban growth, economic activity and transport emissions across the continent, CAMS said, combined with dense populations. That means the health and agricultural costs of ozone are concentrated where the fewest people can easily avoid them: in crowded cities, among outdoor workers, and in farming communities. Oceania's cleaner result, by contrast, shows that lower precursor emissions and different weather patterns can keep ozone within healthier bounds.

There is also a monitoring lesson. CAMS argued that only a system combining satellites, ground stations and modelling can show how pollution moves across borders — and therefore where coordinated action is needed. Without that picture, a country might cut its own emissions yet still breathe polluted air carried from elsewhere, or miss the heatwave days when ozone spikes most sharply.

What Happens Next

CAMS's prescription is practical rather than dramatic: robust policies to reduce precursor emissions, air-quality plans at national and city level, and continuous monitoring and forecasting so that authorities can warn the public on high-ozone days. A United Nations report cited in the 2 November coverage reinforced the same point, warning that reducing greenhouse gas emissions is essential to mitigate global warming — a step that would also improve air quality and reduce transboundary pollution risks.

For governments heading to Antalya, the ozone findings offer a near-term, health-focused argument for faster emission cuts, even as the formal COP agenda centres on longer-term climate targets. For cities, the immediate tools are more familiar: traffic and industrial emission controls, heatwave health warnings that include air quality, and protections for outdoor workers and vulnerable groups on high-ozone days.

For the public, the report is a reminder that "air pollution" is not one thing. Fine particles from smoke and dust get most of the attention, but on hot, sunny days an invisible gas can quietly push air quality into the dangerous range — and, as CAMS found in 2026, it did so for nearly two in every five people on Earth.

Illustration: People walking through a hazy city on a hot day, symbolising everyday exposure to poor air quality — an illustration, not a photograph of any real people or event.

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FAQ

What is ground-level ozone?

Ground-level, or tropospheric, ozone is a harmful gas that forms near the Earth's surface when pollutants from transport, industry and other sources react in sunlight and heat. It is different from the protective ozone layer in the stratosphere.

How many people were exposed to dangerous ozone in 2026?

According to CAMS's Atmosphere Watch report, nearly 40 per cent of the world's population was exposed to extremely high ozone levels during the first eight months of 2026, and only about 5 per cent experienced ozone levels rated "good" under WHO guidelines.

Which region was hit hardest?

Asia, according to CAMS. About 60 per cent of Asia's population faced extremely high ozone, rising to about 90 per cent when "poor" and "very poor" exposures are included. Europe and North America were the next most affected regions.

Why does heat make ozone worse?

Ozone forms faster in sunlight and high temperatures, so heatwaves can sharply raise ozone levels even when underlying emissions do not change. CAMS calls this the "ozone-climate penalty".

What can reduce ground-level ozone?

Cutting the precursor pollutants from transport, industry and energy — the same emission cuts that help the climate — alongside city air-quality plans, continuous monitoring and public warnings on high-ozone days, according to CAMS.

Sources

Copernicus Atmosphere Monitoring Service, "Copernicus Atmosphere: 40% of global population exposed to harmful ozone pollution, amid transboundary pollution in 2026", 30 September 2026; CAMS Atmosphere Watch 2026, Ozone chapter; Indonesia Now, "Ozone Pollution Threatens 40% of Global Population, Asia Hardest Hit", 2 November 2026; Earth.com, "Ozone pollution reached dangerous levels for billions of people in 2026"; DigiconAsia, "Dangerous ground-level Ozone affects 40% of world in first six months of 2026: report", 2 October 2026.