Improving Environmental Justice by Focusing on Emission Location: Diesel PM2.5 in Southern California

Abstract

For exposure to urban air pollution, disparities by race, ethnicity, and socioeconomic class are well documented, but there are few methods or tools to evaluate or quantify the justice and equality effects of emission-reduction options. That gap hampers the advancement and implementation of rigorous policies to address environmental justice. Here, I employ state-of-the-science air dispersion modeling for diesel-generated fine particulate matter in Southern California to estimate how location-based changes in fine particle emissions would impact four goals: health impact, exposure efficiency, exposure equality, and exposure justice. My results explore how spatially targeted reductions may improve environmental justice and equality. Results indicate potential trade-offs (e.g., an increase in equality but reduction in justice) as well as opportunities for “win-wins”: for a region I identify, a 2.6% emission-reduction would benefit overall average exposure, exposure inequality, and exposure injustice by 5%, 6%, and 18%, respectively. As another example, rerouting trucks to avoid hot spots of exposure disparity could improve exposure justice up to 67% and reduce the potential exposure of the truck emissions by 17%. Understanding the spatial patterns of environmental justice, and the connections to spatial patterns in emissions, may highlight how targeted emission-reduction can help maximize efficiency and justice-based goals.