Community urbanization and hospitalization of adults for asthma

Asthma research has traditionally focused on children and the elderly, the two populations considered most susceptible to complications. The prevalence of asthma in the adult population (19-64 years of age) is, however, gaining recognition as a formidable clinical and public health problem. Few studies have compared the incidence of adult asthma hospitalizations in urban and nonurban areas. The study reported here, using population size, population density, and traffic-related factors to define urban versus nonurban environments, selected six Pennsylvania counties to test the hypothesis that the degree of urbanization influences the asthma hospitalization rate for adults. The study group comprised adults 19-64 years of age who were hospitalized for asthma (as the primary diagnosis) from 1999 to 2001. To define urbanization in relation to traffic, the study used daily vehicular traffic count and miles of roads/highways for each of the six counties. The authors found a decrease in the adult asthma hospitalization rate as urbanization decreased in some of the counties. For other counties, however, the rate increased as urbanization decreased. The counties in which the latter was observed had depressed measures of socioeconomic status. These findings suggest that depressed socioeconomic conditions may supersede exposure to traffic-related pollution as a factor associated with asthma hospitalizations.