Downscaling Environmental Justice Analysis: Determinants of Household-Level Hazardous Air Pollutant Exposure in Greater Houston

Environmental justice (EJ) research has relied on ecological analyses of coarse-scale areal units to determine whether particular populations are disproportionately burdened by toxic risks. This article advances quantitative EJ research by (1) examining whether statistical associations found for geographic units translate to relationships at the household level; (2) testing competing explanations for distributional injustices never before investigated; (3) examining adverse health implications of hazardous air pollutant (HAP) exposures; and (4) applying an underutilized statistical technique appropriate for geographically clustered data. Our study makes these advances by using generalized estimating equations to examine distributive environmental inequities in the Greater Houston (Texas) metropolitan area, based on primary household-level survey data and census block–level cancer risk estimates of HAP exposure from the U.S. Environmental Protection Agency. In addition to main statistical effects, interaction effects are modeled to examine whether minority racial or ethnic status modifies the effects of other variables on HAP cancer risk. In terms of main effects, Hispanic and black status as well as the desire to live close to public transit exhibit robust associations with HAP cancer risk. Interaction results reveal that homeownership and homophily (i.e., the desire to live among people culturally similar to oneself) are associated with higher HAP cancer risk among Hispanics and blacks but with lower risk among whites. Disproportionate risks experienced by Hispanics and blacks are attributable neither to dampened risk perceptions nor the desire to live close to work. These findings have implications for EJ research and practice in Greater Houston and elsewhere.