Urbanization

Tokyo, JapanRapid urbanization is the dominant demographic trend in the 21st century. Urban design must focus on optimizing natural resources and human health. When building and managing cities, it must be a priority to reduce the overall ecological footprints by reducing impacts on biodiversity; air and water pollution; and per capita energy, water, and arable land use. Designing highly efficient cities and simultaneously capitalizing on health co-benefits, such as cleaner air and using physical activity as transportation, could make an enormous positive impact on health. Further research is needed to develop principles of effective sustainable urban design that promote the physical and mental health of urban dwellers while reducing the global ecological footprint of the world's cities.

Learning Objectives

  • L1: Compare and contrast the health benefits with the health harms of urbanization.
  • L2: Explain the drivers of regional urbanization, including sociocultural and economic factors.
  • L3: Describe ongoing changes in the demographics of urban centers.
  • L4: Propose potential interventions in the urban context to improve health, considering economic, political and sociocultural influences.

 

Curriero FC, Heiner KS, Samet JM, Zeger SL, Strug L, Patz JA. Temperature and mortality in 11 cities of the eastern United States. Am J Epidemiol [Internet]. 2002;155 :80-7. Publisher's VersionAbstract

Episodes of extremely hot or cold temperatures are associated with increased mortality. Time-series analyses show an association between temperature and mortality across a range of less extreme temperatures. In this paper, the authors describe the temperature-mortality association for 11 large eastern US cities in 1973-1994 by estimating the relative risks of mortality using log-linear regression analysis for time-series data and by exploring city characteristics associated with variations in this temperature-mortality relation. Current and recent days' temperatures were the weather components most strongly predictive of mortality, and mortality risk generally decreased as temperature increased from the coldest days to a certain threshold temperature, which varied by latitude, above which mortality risk increased as temperature increased. The authors also found a strong association of the temperature-mortality relation with latitude, with a greater effect of colder temperatures on mortality risk in more-southern cities and of warmer temperatures in more-northern cities. The percentage of households with air conditioners in the south and heaters in the north, which serve as indicators of socioeconomic status of the city population, also predicted weather-related mortality. The model developed in this analysis is potentially useful for projecting the consequences of climate-change scenarios and offering insights into susceptibility to the adverse effects of weather.

Knudsen AB, Slooff R. Vector-borne disease problems in rapid urbanization: new approaches to vector control. Bull World Health Organ [Internet]. 1992;70 :1-6. Publisher's VersionAbstract

Owing to population growth, poor levels of hygiene, and increasing urban poverty, the urban environment in many developing countries is rapidly deteriorating. Densely packed housing in shanty towns or slums and inadequate drinking-water supplies, garbage collection services, and surface-water drainage systems combine to create favourable habitats for the proliferation of vectors and reservoirs of communicable diseases. As a consequence, vector-borne diseases such as malaria, lymphatic filariasis and dengue are becoming major public health problems associated with rapid urbanization in many tropical countries. The problems in controlling these diseases and eliminating vectors and pests can be resolved by decision-makers and urban planners by moving away from the concept of "blanket" applications of pesticides towards integrated approaches. Sound environmental management practices and community education and participation form the mainstay of some of the most outstanding successes in this area. On the basis of these examples, it is argued that the municipal authorities need to apply a flexible methodology, which must be based on the possibilities of mobilizing community resources, with minimal reliance on routine pesticidal spraying. In this way, vector control becomes a by-product of human development in the city environment. This is now a true challenge.

Bratman GN, Hamilton PJ, Daily GC. The impacts of nature experience on human cognitive function and mental health. In: Ostfeld R, Schlesinger W The Year in Ecology and Conservation Biology. Vol. 1249. Ann. NY Acad. Sci. ; 2012. pp. 118-136. Publisher's VersionAbstract

Scholars spanning a variety of disciplines have studied the ways in which contact with natural environments may impact human well-being. We review the effects of such nature experience on human cognitive function and mental health, synthesizing work from environmental psychology, urban planning, the medical literature, and landscape aesthetics. We provide an overview of the prevailing explanatory theories of these effects, the ways in which exposure to nature has been considered, and the role that individuals' preferences for nature may play in the impact of the environment on psychological functioning. Drawing from the highly productive but disparate programs of research in this area, we conclude by proposing a system of categorization for different types of nature experience. We also outline key questions for future work, including further inquiry into which elements of the natural environment may have impacts on cognitive function and mental health; what the most effective type, duration, and frequency of contact may be; and what the possible neural mechanisms are that could be responsible for the documented effects.

Knowlton K. Urban history, urban health. Am J Public Health [Internet]. 2001;91 :1944-6. Publisher's VersionAbstract

Over the course of the 20th century, the United States became an urban nation: 80% of Americans now live in metropolitan areas. Supplying basic sanitary services-drinking water, sewers, and garbage removal-to these cities is a gargantuan task, yet most people have little understanding of urban infrastructure systems and their enormous regional ecologic impacts. Municipalization of sanitary services, especially since 1880, distanced people from their wastes and gave city dwellers a simplistic experience of one-way material flow through cities, without knowledge of the environmental costs. Most sanitary infrastructures were built primarily for durability and lack the elasticity to meet changing needs. The challenge now is to adapt sanitary systems for flexibility and simultaneously move from unchecked material consumption toward resource-based thinking.

Bradley CA, Gibbs SEJ, Altizer S. Urban land use predicts West Nile virus exposure in songbirds. Ecological Applications [Internet]. 2008;18 :1083-92. Publisher's VersionAbstract

Urbanization is a widespread phenomenon that is likely to influence the prevalence and impact of wildlife pathogens, with implications for wildlife management and public health policies toward zoonotic pathogens. In this study, wild songbird populations were sampled at 14 sites along an urban–rural gradient in the greater metropolitan Atlanta (Georgia, USA) area and tested for antibodies to West Nile virus (WNV). The level of urbanization among sites was quantitatively assessed using a principal component analysis of key land use characteristics. In total, 499 individual birds were tested during the spring and summer over three years (2004–2006). Antibody prevalence of WNV increased from rural to urban sites, and this trend was stronger among adult birds relative to juveniles. Furthermore, antibody prevalence among Northern Cardinals (Cardinalis cardinalis) was significantly higher than in other songbird species along the urban gradient. Findings reported here indicate that ecological factors associated with urbanization can influence infection patterns of this vector-borne viral disease, with likely mechanisms including changes in host species diversity and the tolerance or recovery of infected animals.

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