Residential proximity, traffic volume, social structure and childhood asthma

Objectives. This study has three objectives: (1) To investigate the association between traffic pollution and childhood asthma; (2) To explore the areas where clusters of asthmatic cases might occur; (3) To examine the impact of social structure (demographics, SES and housing) on pediatric asthma prevalence.; Methods. Data of patients with asthma and certain other respiratory conditions, G-I infections, G-I non-infections or convulsions who sought services at CCHMC between April 1996 and October 1997 was retrieved. Geocoded patients' data, the 1990 census data and ADT data were integrated onto the base map of CinRMA. Using traffic proxies (residential proximity, direct distance, ADT and vehicle types), the impact of traffic on health outcomes at individual and community levels was examined with SAS and GIS. The effect and patterns of social structure such as demographics, housing and SES were examined. Finally, an Asthma Risk Indicator at the census block group level was constructed.; Results. Variables associated with race, not residential proximity, increase the odds of getting asthma for African Americans by 1.9 times (OR = 1.91, 95% CI = 1.77∼2.07) over that for Caucasian Americans. No significant differences are found between the asthmatic group and the control group in the situations as below: prevalence around 3-Rd intersections (OR = 0.95), the average of the shortest distance from the residence to the nearest road segment, and to the road segments where the ADT is above the 80th percentile. Most likely spatial clusters of childhood asthma are identified. Residents living in several of the cluster-areas have an odds ratio of asthma above 3. Demographics, population density, household size, median house values, and SES in the census block groups where two study groups lived are different. Hence, an "Asthma-Risk Indicator", which concurrently takes census-block-group specific median house values and population density into account, is generated to highlight the census block groups where the residents have a higher risk for pediatric asthma if the scale of the indicator is lower.; Conclusions. No higher childhood asthma prevalence is found for residents living closer to traffic roads or living in the area where more vehicles (cars and trucks) pass by. Spatial clusters of childhood asthma are identified. Races, SES, population density, household size all show differences between the two groups. An Asthma Risk Indicator is generated. The higher its scale, the lower the asthma prevalence in that census block group that is observed.