Emerging drivers of urban aerosol increase global change vulnerability in a US megacity

Urban aerosol pollution is evolving rapidly with global change and poses significant risks to public health. Measurements and machine learning-enabled chemical analysis of aerosol from a suburb of New York City in 2023 reveal emerging sources and drivers in a modern megacity. Regional wildfire smoke averaged 25% of organic aerosol (OA) mass and drove variability via enhancements of biogenic OA formation within smoke plumes. This biogenic OA contributed 40% of aerosol mass. Urban heatwaves enhanced both biogenic and anthropogenic sources, with ~20% of OA mass exhibiting significant heatwave sensitivity. For the first time, volatile chemical product (VCP) compounds were directly observed, speciated, and characterized in urban aerosol. Contributions to total OA averaged 15%, double the contribution from traffic. Together, this work identifies wildfire smoke, biogenic emissions, heat, and emerging anthropogenic emissions as critical global change vulnerabilities for North American urban aerosol pollution that pose unique challenges for control strategies.