CAMS finds widespread ground-level ozone exposure in 2026

The inaugural Copernicus Atmosphere Monitoring Service (CAMS) Atmosphere Watch review found widespread exposure to ground-level ozone between January 1 and September 15, 2026. One-third of the global population—34%—experienced “extremely poor” ozone air quality, while 17% experienced “very poor” conditions. The review also drew attention to pollution moving across borders, making coordinated action important alongside local emissions cuts. 31713

What the reported air-quality categories show

A report on the findings gives 34% for “extremely poor” conditions, 17% for “very poor,” and 5% for “good” long-term ozone levels. Together, the two poorest categories account for about half of the global population, in line with CAMS’s summary. The available figures do not provide a reliable percentage for every other category. 1725

CAMS’s ozone page also describes almost 40% of the world’s population as exposed to “extremely high” ozone levels. That figure is not directly interchangeable with the 34% classified as experiencing “extremely poor” air: the available summaries do not explain the difference between those measures. 520

Asia had the greatest reported exposure

Exposure was persistent across Asia. One account reports that 53% of the region’s population experienced extremely poor ozone air and another 22% experienced very poor conditions. CAMS separately describes 60% of Asian residents as exposed to extremely high ozone; the sources do not specify how that figure maps to the category percentages. 35

Europe and North America also had days with very high exposure during summer heatwaves. A news account names Delhi, Rio de Janeiro, Mexico City, Milan and Cairo among cities with the highest exposure to polluted air, but does not establish that this is an ozone-only ranking. 52

The WHO benchmarks depend on the measure

The sources cite two WHO ozone benchmarks. CAMS says the WHO target for peak-season ozone is below 60 micrograms per cubic metre (µg/m³). A news report describes “extremely poor” conditions using a different benchmark: ozone above 100 µg/m³ averaged over eight hours. These are different averaging measures, so they should not be treated as the same threshold. 517

Heat, emissions and fires contribute to the concern

Ground-level ozone forms when pollutants react in sunlight and high temperatures. CAMS links the 2026 exposure picture to extreme heat and human-caused air pollution, and its review also covers wildfire smoke. The sources identify these as contributing concerns but do not quantify how much each factor contributed to ozone exposure. 2013

CAMS also warned that extreme El Niño conditions were expected to continue in the coming months and could increase wildfire concerns. That is a forward-looking risk, not a measure of how much El Niño contributed to ozone levels during the reporting period. 96

Pollution crosses borders, strengthening the case for cooperation

CAMS’s review documented air pollution moving across borders and continents. That means air quality in one place can be affected by pollution transported from elsewhere, alongside local emissions. The service presented the findings as a reason for coordinated international action ahead of COP31, where climate, air quality and public health are connected concerns. 413

For Europe, reporting on the review says ozone showed no clear downward trend and remained an issue. The available sources do not establish that progress stalled across North America, or provide quantified health effects attributable to the reported exposure. 19