Over a third of world population faced dangerous ozone pollution in 2026, report finds

More than a third of the world's population — around 34% — was exposed this year to extremely high levels of ozone pollution, driven by a combination of heatwaves, wildfires and human-caused emissions, according to a new report from the European Union's Copernicus climate monitoring service.

The findings highlight the growing role that extreme heat and forest fires are playing in worsening air quality, as high temperatures and fire smoke combine with pollution from vehicles, industry and other human activities to push ground-level ozone concentrations to dangerous levels in many regions.

Ground-level ozone, unlike the protective ozone layer high in the atmosphere, is a harmful air pollutant that forms when sunlight reacts with emissions from sources such as vehicle exhaust and industrial activity. Exposure to high concentrations can cause respiratory problems and aggravate conditions such as asthma, posing particular risks to children, the elderly and people with existing health conditions.

Copernicus researchers linked this year's elevated exposure levels to the compounding effects of record or near-record heatwaves across multiple continents combined with an active wildfire season, conditions that create an environment favorable to ozone formation even as they also directly worsen air quality through smoke.

The report adds to a growing body of evidence pointing to the health risks posed by climate change, with scientists warning that as global temperatures continue to rise, episodes of extreme heat and wildfire activity are likely to become more frequent, further increasing the population exposed to hazardous ozone levels.

Public health officials in affected regions have previously urged residents to limit outdoor activity during periods of poor air quality, particularly during heatwaves when ozone levels tend to peak.

The Copernicus service, which monitors atmospheric conditions across Europe and globally, did not specify in the report how this year's ozone exposure levels compare with prior years, though the scale of the figure underscores the extent to which climate-driven conditions are now shaping global air quality.