Environmental Hazards and Structural Covariates of US Homicide Rates: Methodological Considerations When Investigating the “Ecology” of Violence

Environmental hazards such as air pollutants have increasingly been investigated as macro-level correlates of violent criminal activity, including rates of homicide across space. Such efforts highlight the growing appreciation in the social sciences of the interaction between humans and the natural environment, particularly within the subfields of environmental sociology and green criminology. However, while such investigations broaden the scope of relevant social scientific inquiry, they often fail to appreciate the theoretical and methodological contributions from prior crime and deviance scholars. Given the expansive history within the social sciences of investigating structural covariates of homicide rates, this effort seeks to determine whether differential levels of particulate matter with aerodynamic diameters smaller than 2.5 μm (PM_2.5) can be observed as unique predictor of lethal violence in the US after simplifying the dimensionality of the regressor space. Results indicate that while air pollution levels share covariate space with population size and density, their combined influence represents a robust predictor of county-level homicide rates in the various spatial econometric models estimated.