The built environment and asthma: Los Angeles case study

Abstract

This study aimed to identify urban characteristics that contribute to the incidence of asthma, applying various elements of built environment relevant to variations in traffic volume and traffic-related air pollution. We used built environment metrics in three dimensions (density, diversity, design) and examined whether those metrics are associated with asthma emergency department (ED) visits among 2343 census tracts in Los Angeles County by applying spatial epidemiologic tools (spatial regression, GIS mapping). We found that increases in population density, land use mix, and the share of open/recreation area are negatively associated with asthma ED visits but found no significant effects of household and street density. The results of neighborhood risk factors (percent of African American, less than high school, median household income, unemployment) confirm the overwhelming impact of the disadvantaged neighborhoods on asthma epidemiology. The findings indicate that high population density contributes to a reduction in acute care utilization for asthma and underscore the beneficial roles of land use mix and a larger share of open/ recreation space for respiratory health by promoting physical activity and improving air quality.