Urbanization and health: the mediation role of slums

This paper investigates the impact of urbanization on health outcomes in Africa, with a focus on the mediating role of slum prevalence. Slums are operationalized following UN-Habitat definitions, using indicators such as lack of durable housing, inadequate sanitation, limited access to clean water, overcrowding, and insufficient access to basic services. Applying causal mediation analysis to a panel of 40 African countries from 2000 to 2022, we find that urbanization has a direct positive effect on life expectancy; however, this is partly offset by a significant negative indirect effect transmitted through the expansion of slums. Results also reveal age-specific heterogeneity: urbanization significantly reduces adult mortality, with the beneficial direct effect outweighing the adverse indirect effect. In contrast, for children, both the direct and indirect effects of urbanization on mortality are detrimental. These findings underscore the importance of urban development and health policies that directly target slum conditions—particularly through improvements in housing, sanitation, and service delivery—to mitigate the adverse health consequences of rapid urban growth, especially for children.