PROJECT SUMMARY Racial and ethnic minority communities experience poorer outdoor air quality and face greater burdens of lung disease, particularly from asthma. The close proximity of minority neighborhoods to both fixed and mobile air pollution sources combined with the disproportionate burden of asthma morbidity among these populations supports the overarching hypothesis that racial and ethnic disparities in asthma are caused by urban planning policies that result in exposure to more toxic sources of air pollution (AP). We propose the following Specific Aims to test this hypothesis: 1) To characterize AP sources, estimate AP concentrations, and examine their associations with neighborhood sociodemographic characteristics across the State of Texas. 2) To identify the AP sources that contribute to racial and ethnic childhood asthma disparities. 3) To explore the effects of zoning and gentrification on the distribution of AP sources across neighborhoods in Travis County. Evidence supporting this hypothesis would constitute a major advance by (1) identifying AP sources that contribute directly to childhood lung health disparities and (2) linking urban planning decisions to inequities in the location of AP sources. The proposed work would fill a critical evidence gap needed to develop new approaches to AP regulation and urban planning, which would be strongly positioned to meaningfully reduce lung health health disparities.