Assessing the health impact of urbanization.

Several components of urbanization influence health status, but it is difficult to attribute changes in health status to any particular component. The overall impact may be estimated by relating the degree of urbanization of populations to some proxy measure, like the under-5 mortality rates. In this respect the net effect of urbanization is shown to be beneficial. A variety of survey and computational methods have been used to clarify the relationship. Some illustrate the effects of urbanization upon particular clinical conditions, such as promoting the eradication of leprosy, others of particular components, such as overcrowding and pollution, on infant mortality. To help set goals, excess or avoidable mortality may be computed for a country or region by relating its experience to current mortality levels in a developed country; and changes in the levels of avoidable mortality from sentinel conditions such as infectious diseases may be related to changes in particular aspects of urbanization, e.g. improvements in levels of sanitation. Migration to the urban environment imparts the tendency to acquire the health characteristics of the host population. Rapid urbanization causes problems of psychosocial adjustment for older children. Urbanization may impact upon the incidence and prevalence of disability. Where sex-age disability-survey data exist, they may be combined with age-specific mortality data to construct an index of disability-free life expectancy, a more subtle measure for assessing the progressive impact of urbanization. Up to now, however, there have been no international studies of how levels of disability change according to the progress of urbanization, and there are no international census or survey recommendations for harmonizing the classification of disabled people.(ABSTRACT TRUNCATED AT 250 WORDS)