Long-range PM2.5 pollution and health impacts from the 2023 Canadian wildfires

Smoke from extreme wildfires in Canada adversely affected air quality in many regions in 20231,2. Here we use satellite observations, machine learning and a chemical transport model to quantify global and regional PM2.5 (particulate matter less than 2.5 μm in diameter) exposure and human health impacts related to the 2023 Canadian wildfires. We find that the fires increased annual PM2.5 exposure worldwide by 0.17 μg m–3 (95% confidence interval, 0.09–0.26 μg m–3). North America had the largest increase in annual mean exposure (1.08 μg m–3; 0.82–1.34 μg m–3), but there were also increases in Europe (0.41 μg m–3; 0.32–0.50 μg m–3) owing to long-range transport. Annual mean PM2.5 exposure in Canada increased by…