Global hotspots of compound extreme heat-pollution linked to local surface and atmospheric conditions

Extreme heat and particulate matter (PM2.5) pollution are among the deadliest environmental hazards that threaten humans and ecosystems. Their co-occurrence, known as compound heat-pollution events, can amplify risks far beyond those posed by either hazard alone, but their global patterns and physical mechanisms are yet to be understood. Here, we present a global assessment of compound heat-pollution events from 2003 to 2020 at 1-km fine scale. We identify two hotspots: Sub-Saharan Africa and the Indus River Valley, where compound heat-pollution events occur most frequently. These compound events are typically associated with clear and dry conditions characterized by increased solar radiation and reduced precipitation, humidity, and cloud cover. Notably, during compound events, there is a pronounced high-pressure anticyclone appearing in the Indus River Valley, while weaker atmospheric circulation changes appear in Sub-Saharan Africa. Our findings advance understanding of compound heat-pollution events and support improved risk assessments and regional adaptation strategies. Sub-Saharan Africa and Indus River Valley are two hotpots of the occurrence of compound heat-pollution events in recent decades, though with different circulation backgrounds, revealed by fine scale global assessment.