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Spatial Clustering of Hazardous Waste, Water, Air Violations in the U.S.

July 2021
Environmental Research Letters


We examine spatial patterns of three types of Environmental Protection Agency violation, hazardous waste, water, and air quality, at the facility level. Since facilities operate independently, our null hypothesis is that their violations should be spatially randomly distributed. That is, we do not expect to observe spatial clusters of violations. In addition, systemic factors such as socio-demographic characteristics as well as environmental justice indices should not correlate with violations. Empirically, we find both hypotheses are refuted. Our findings confirm that environmental inequalities have been exacerbated by underlying social vulnerabilities, particularly in the case of Native Indian territories, which consistently show a disproportionately high number of environmental violations. We identify 'hot spots', spatial clusters where the number of violations is higher than expected in such a way that cannot be explained by socio-demographic or environmental factors. These hot spots call for local case studies to further investigate causes of spatial clustering of violations.