Cities and the Health of the Public

1. A Framework for the Study of Urban Health

 1 A Framework for the Study of Urban Health Sandro Galea, Nicholas Freudenberg, and David Vlahov Introduction Today, city life is the norm for an ever-growing proportion of the world’s population , and recent projections estimate that half of the world’s population will live in urban areas by 2007 and three-quarters by 2030. Much of this growth will be in the developing world: By 2030, all of the world’s largest cities are projected to be in Africa, Asia, and Latin America. This international expansion of cities reflects population growth, increased survival, and migration and deserves attention from public health professionals because the urban environment influences every aspect of health: the food people eat, the air they breathe, the water they drink, where (or if) they work, the housing that shelters them, their sex partners and family arrangements, where they go for health care, the danger they encounter on the street, and who is available for emotional and financial support. More than ever before, understanding what causes health and disease and how to improve public health around the globe requires an improved awareness of how urban life affects well‑being. The aim of this chapter is to introduce a framework for the study of urban health, but first we require consistent definitions of key terms, a significant challenge because of the multiple disciplines (including public health, social sciences, urban planning and architecture) that have been involved in the study of facets of urban health. We begin, therefore, by addressing terminology, viewpoints, and considerations that can inform our focus on the health of urban populations. We then present a conceptual framework that we find useful to help think about how cities shape population health. We elaborate on elements of this framework in Chapter 2. Although we aim to contribute to a global perspective on urban health, in this  Part I: Introduction book we focus on the circumstances and conditions of the United States. We take this perspective because our own experience is here and we believe that an under­ standing of urban health must emerge from concrete analysis of specific situations . Where appropriate, we link broader global forces to the experience in the United States (e.g., immigration); however, we recognize that the experience in the United States does not and cannot adequately describe or address the effects of urban living in developing and other developed countries. In the United States, urbanization and urban development have been major historical trends for the past 150 years, driving changes in multiple areas, such as economic development, education , criminal justice, transportation, and housing. Therefore, in this book we aim to draw lessons from the U.S. experience that can guide research and intervention domestically and globally. Key Terms and Definitions Defining Urban The U.S. Bureau of the Census defines “an urbanized area” as “a place and the adjacent densely settled surrounding territory that together comprise a minimum population of 50,000 people.” Moreover, “the ‘densely settled surrounding territory ’ adjacent to the place consists of territory made up of one or more contiguous blocks having a population density of at least 1,000 people per square mile.”1 The Census Bureau thus provides a dichotomy, designating territory, population, and housing units within specific size and density parameters as urban areas and all others are nonurban. The U.S. Census definition is limited in many respects. First, a more nuanced appreciation of gradations of urban may be helpful. In the early 21st century, few cities exist in isolation, clearly set apart from other urban areas by vast underpopulated space (e.g., Las Vegas 10 years ago). Most cities (e.g., Hartford, Conn., Atlanta , Ga., Los Angeles, Calif., Detroit, Mich.) are part of a far-reaching, densely populated area that continues relatively uninterrupted for miles beyond the actual city and city-center. This broader zone is often called a “metropolitan area,” which the U.S. Census Bureau defines as “a city with a population of at least 50,000 people or an urbanized core area of at least 50,000 people who are closely integrated socially and economically with the core.” Figure 1.1 illustrates the changing proportion of the U.S. population living in metropolitan areas.2 In the past two decades, urban and suburban settlements within metropolitan areas have converged and now share many features of urban living and their consequences ; a dichotomous definition of urban fails to recognize this metropolitan phenomenon. Since half the U.S. population lives in this...