More than half of the world’s population was exposed to unhealthy air this year, according to an analysis by the European Union’s Copernicus Atmosphere Monitoring Service (CAMS). The analysis found that between January 1 and September 15, 34% of the world’s population was exposed to “extremely poor” air quality, while 17% experienced “very poor” air quality.
The main source of the pollution was ground-level ozone, commonly known as summer smog. Ozone forms when gases from vehicles and industry react with sunlight, and heatwaves accelerate this process.

According to the report, extreme heatwaves and wildfires caused unhealthy levels of smog and smoke worldwide in 2026. Due to wildfire smoke carried across borders, two out of every three people in North America and 45% of Europe’s population were exposed to poor or very poor air quality.
Approximately 106 million people in Canada and the United States were exposed to dangerous or unhealthy air between July 15 and 17 because of major wildfires in Canada.