Particulate matter-attributable mortality and relationships with carbon dioxide in 250 urban areas worldwide

Urban air pollution is high on global health and sustainability agendas, but information is limited on associated city-level disease burdens. We estimated fine particulate matter (PM_2.5) mortality in the 250 most populous cities worldwide using PM_2.5 concentrations, population, disease rates, and concentration-response relationships from the Global Burden of Disease 2016 Study. Only 8% of these cities had population-weighted mean concentrations below the World Health Organization guideline for annual average PM_2.5. City-level PM_2.5-attributable mortality rates ranged from 13-125 deaths per 100,000 people. PM_2.5 mortality rates and carbon dioxide (CO₂) emission rates were weakly positively correlated, with regional influences apparent from clustering of cities within each region. Across 82 cities globally, PM_2.5 concentrations and mortality rates were negatively associated with city gross domestic product (GDP) per capita, but we found no relationship between GDP per capita and CO₂ emissions rates. While results provide only a cross-sectional snapshot of cities worldwide, they point to opportunities for cities to realize climate, air quality, and health co-benefits through low-carbon development. Future work should examine drivers of the relationships (e.g. development stage, fuel mix for electricity generation and transportation, sector-specific PM_2.5 and CO₂ emissions) uncovered here and explore uncertainties to test the robustness of our conclusions.