PM2.5 air pollution inequities in the US by sector and state: Past trajectories and future directions

Abstract

On average in the United States (US), low-income communities and communities of color face disproportionate burdens of air pollution and associated health impacts. Much of the effort to reduce these disparities will need to occur at the state level, through the targeting of specific emission sources and exposures. We present the first analysis of exposure disparities in the US that systematically investigates temporal trends, disaggregated by economic sector and state. Our approach combines a recently released time-series (2002 to 2019) emission inventory (EQUATES) with a computationally efficient air pollution model (InMAP Source-Receptor Matrix) to predict annual average exposure to ambient PM2.5 in each census tract in the contiguous US, disaggregated by emission sector. We find that, in general, absolute disparities have decreased, but relative disparities remain largely unchanged. This pattern holds for some sectors (e.g., transportation and electricity) but not others (e.g., disparities are largely unchanged for agriculture emissions and are generally increasing for residential and cooking emissions). Some state-sector combinations exhibit distinct patterns (e.g., most-recent disparities in New York are dominated by cooking and in Florida by construction). Of all sectors, industrial emissions contribute the largest exposures and the greatest exposure disparities. Agriculture and residential energy use are also large contributors to most-recent disparities, underscoring that inequities persist in sectors historically subject to less regulatory focus. Overall, our findings reveal how disparities have changed during 2002 to 2019 for each sector-state combination and elucidate which sectors each state should focus on to address recent disparities.