Half of world’s population exposed to dangerous levels of ozone in 2026

A new analysis by the Copernicus Atmosphere Monitoring Service finds that about 51 percent of the world’s population experienced "very poor" or "extremely poor" average ground-level ozone concentrations over the past six months of 2026, with 34 percent in the "extremely poor" category and only 5 percent experiencing "good" conditions. Ground-level ozone, the main component of smog, forms when emissions such as nitrogen oxides, carbon monoxide and volatile organic compounds from fossil-fuel combustion and wildfires react with sunlight and heat; this summer's intense heat waves, amplified by climate change, drove elevated ozone formation and accumulation.

The worst exposures occurred in Asia, where 75 percent of people faced at least very poor ozone levels, followed by high burdens in North America and Europe. The analysis emphasizes that ozone and its precursor pollutants travel across borders, complicating mitigation and requiring international coordination. Elevated ozone concentrations damage lungs, increase respiratory illness, harm crops and ecosystems, and thus tie air quality directly to public health and food security; CAMS leadership framed ozone pollution as a stark example of how climate, atmospheric chemistry and livelihoods are interconnected.