Abstract
OBJECTIVE: A grassroots environmental-justice organisation in Kansas City has been examining the disproportionate exposure to air pollution experienced by residents living fenceline to the largest classification railyard in the USA. Prior analyses showed limited increased risk for asthma exacerbation for patients with asthma living closer to toxic release inventory (TRI) facilities and railyards. In this study, we assessed geographical asthma and environmental disparities, to further explore community-level disparities. DESIGN: This is a cross-sectional study of population-level asthma rates, which included rates for all asthma encounters and acute asthma encounters (urgent care, emergency department, inpatient admission). Distances from census-tract centroids to nearest TRI facilities, railyards and highways were calculated. The association between asthma rates and distances was examined using Kendall's τ correlation and multivariable Poisson regression models. SETTING: We used electronic medical record data from the regional paediatric hospital, census and Environmental Protection Agency (EPA) air monitoring data. PARTICIPANTS: Patients with 2+ asthma encounters during the EPA study timeframe were identified. RESULTS: Residential distance from railyards exhibited a significant negative correlation with overall (-0.36 (CI -0.41 to -0.32)) and acute (-0.27 (CI -0.32 to -0.22)) asthma rates. Asthma rates were elevated among tracts north of the closest railyard (incident rate ratio: 1.38; CI 1.35 to 1.41) when compared with southern directionality. An increased distance from the nearest railyard of 3 km was associated with a decrease in overall asthma rates of 26%. CONCLUSION: Significant negative associations between proximity to all pollution source types and asthma rates were observed. This community-level research has served as a tool for community engagement and will be used to support proposed local policy. Environmental justice work addresses local concerns involving small, limited datasets, if the data exist at all. The academic epidemiological platform may reconsider acceptable approaches to small population research in order to better serve communities with the most need.