July 28, 2022

Cities are complex systems where the dynamics of population size and social interaction give rise to emergent phenomena such as urban scaling. The urban scaling framework describes how city-level characteristics scale with variations in city size. Urban scaling describes the processes by which urban features such as socioeconomics, crime, pollution, consumption patterns, and energy expenditure vary with population growth. Understanding urban population dynamics, and subsequent urban scaling laws, are the first steps toward developing theories aimed toward describing the relationship between city-level characteristics and population health, with many of these characteristics serving as potential policy levers for sustainability, resource allocation, and healthy governance.

A recent research article published in the Journal of Public Health, led by Edwin McCulley, MS, a doctoral research fellow at the Urban Health Collaborative, reviewed the evidence pertaining to the urban scaling of health outcomes. In this scoping review, the research team mapped evidence regarding the associations between population growth, city size and health outcomes, with a focus on studies with an explicit urban scaling framework. The scoping review found that outcomes such as homicides and other crimes are more common in larger cities, suicides are more common in smaller cities, and traffic-related injuries show a less clear pattern that may differ by context and type of injury.

The team also found a gap in the literature for low-income countries (LMICs). This lack of evidence is especially worrisome for LMICs, where poor sanitation, inequalities in resource availability, and overcrowding are especially prevalent in urban areas and may have a large influence on scaling patterns. Most future urban population growth is expected to occur in LMICs, specifically in Latin America, Asia, and Africa, and understanding the consequences of urban growth in these settings should be a priority of future research. With growing urban populations worldwide, the continuous challenge of non-communicable diseases, the importance of injury mortality in the burden of premature mortality, and the re-emergence of infectious diseases, understanding the consequences of our urban world can influence the design and planning of interventions to address unmet public health needs.

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