Megacities, Hazy Air, and Other Not-So-Cool Things: Mapping the Known and Unknown Intersections Between Climate Change, Health, and Urbanization

In an era where climate change is intensifying and urbanization continues to expand, these processes jointly shape environmental exposure and health risk, making their integrated analysis necessary for understanding contemporary disease patterns. This study applies bibliometric network analysis to over 32,000 publications retrieved from PubMed and Lens to examine how climate change, urbanization, and health are structured across complementary knowledge systems. PubMed, as a health-focused database, organizes the literature around a tightly coupled core linking environmental exposure, disease outcomes, and public health response, whereas Lens captures a broader systems-level structure centered on urbanization, infrastructure, economic development, and policy. This contrast reveals that database-specific organization influences not only emphasis but also visibility, shaping which relationships consolidate into stable knowledge and which remain weakly integrated. A key finding is the under-integration of links between environmental exposure and life-course brain health, including neurodevelopmental and neurodegenerative outcomes, which remain fragmented across both systems despite established evidence. Interpreting this as a structural blind zone, rather than an absence of research, highlights limitations in how climate–health knowledge is currently organized. To address this, we introduce air pollution nosography as a framework that aligns city-specific pollutant profiles with their dominant health outcomes, enabling more precise characterization of environmental risk at the urban scale. This approach provides a basis for improved integration across environmental, demographic, and health domains and supports more targeted, adaptive policy design for urban climate–health governance under conditions of uncertainty.