# Global tropospheric ozone exposure levels > Live situation record from CLSTR: https://clstr.news/situations/global-tropospheric-ozone-exposure-levels > Updated: 2026-10-11T01:42:21.000Z. Sources: 6. Developments: 2. A global analysis by the Copernicus Atmosphere Monitoring Service (CAMS) indicates that during the first eight months of 2026, nearly 40% of the world’s population was exposed to extremely high levels of tropospheric ozone. In comparison, only 5% of the population experienced levels meeting World Health Organization standards. Tropospheric ozone is a secondary pollutant formed when nitrogen oxides and volatile organic compounds react in sunlight and high temperatures. This process is intensified by heatwaves and climate change, a phenomenon described as the ‘climate penalty for ozone.’ Findings emphasize that these pollutants can travel thousands of kilometers across borders, impacting ecosystems, crop yields, and human health. Florian Pappenberger, Director General of the ECMWF, noted that the data demonstrates how atmospheric pollution “knows no borders,” highlighting the link between climate change and air quality while calling for global coordination ahead of the COP31 UN climate summit. ## Timeline ### 2026-10-11: Global ozone pollution exposed nearly 40% of population Nearly 40% of the global population was exposed to dangerous tropospheric ozone levels this year, according to a CAMS analysis, highlighting the transboundary nature of air pollution and climate change. 2 sources. https://clstr.news/cluster/global-ozone-pollution-exposed-nearly-40-of-population ### 2026-10-07: Tropospheric ozone exposure affects 40% of global population A Copernicus analysis shows nearly 40% of the global population was exposed to dangerous tropospheric ozone levels in early 2026, driven by heatwaves and human-made precursor pollutants. 4 sources. https://clstr.news/cluster/tropospheric-ozone-exposure-affects-40-of-global-population --- Cite as: Global tropospheric ozone exposure levels. CLSTR, https://clstr.news/situations/global-tropospheric-ozone-exposure-levels