U.S. decarbonization impacts on air quality and environmental justice

Abstract

As policy organizations consider strategies to mitigate climate change, decarbonization initiatives can also reduce health-impacting air pollutants and may affect the associated racial disparities of adverse effects. With the U.S. EPA CO-Benefits Risk Assessment Health Impacts Screening Tool (COBRA), we compare three decarbonization scenarios and their impacts at the regional and county scales. COBRA calculates changes in county-level ambient fine particulate matter (PM2.5), and associated mortality impacts, for each decarbonization scenario. We compare these patterns with demographic data to evaluate the relative exposure reduction benefit across race and ethnicity. Carbon-free electricity would reduce national average ambient PM2.5 concentrations by 0.21 μg/m3, compared with a 0.19 μg/m3 reduction associated with carbon-free industrial activity, and a 0.08 μg/m3 reduction associated with carbon-free light duty vehicle (LDV) transportation. Decarbonization strategies also vary in terms of the racial groups most benefitting from each scenario, due to regional and urban/rural patterns in emission sources and population demographics. Black populations are the only group to experience relative exposure reduction benefits compared to the total population in every scenario, with industrial decarbonization yielding 23% greater reductions in ambient PM2.5 concentrations for Black populations than for the total U.S. population. The largest relative reduction in PM2.5 exposure was found for Asian populations in the carbon-free LDV transportation scenario (53%). The magnitudes of total air quality improvements by scenario vary across regions of the U.S., and generally do not align with the decarbonization policy that achieves the largest equity goal. Only the transportation decarbonization scenario meets the criteria of the Justice40 Initiative nationwide, fulfilling the 2021 commitment by U.S. President Biden that federal investments in clean energy are designed to allocate at least 40% of benefits to disadvantaged communities.

Air quality related equity implications of U.S. decarbonization policy

“…Goforth and Nock found that without strict renewable energy and low carbon targets some electricity sector decarbonization pathways can exacerbate the pollution disparities 28 . These insights also hold beyond the electricity sectors 29 . For example, Zhu et al evaluated two decarbonization strategies (building electrification and truck electrification) in California, and found that while building electrification generates greater overall air quality benefits (~15%), it is comparatively less beneficial to disadvantaged communities 19 .…”

Emerging environmental justice issues at the intersection of transportation and electricity systems

“…Some studies suggest that past policies focused on overall emissions reductions in the electricity sector have not reduced disparities in pollutant exposure [27]. Others suggest that eliminating fossil-fuel electricity generation will have the greatest benefit for White communities, and lower benefits for communities of color [28], and that CO 2 -focused policies will not reduce racial air pollution exposure disparities [29]. However, other studies suggest that policies targeting overall air pollutant emissions reductions align well with reducing impacts to vulnerable populations [30].…”

Capturing Exposure Disparities with Chemical Transport Models: Evaluating the Suitability of Downscaling Using Land Use Regression

“…Recent studies have conducted this type of analysis using Chemical Transport Models (CTMs) to assess the impact of different sectors on air pollution exposure, disparities, and health. − This is done by simulating emission scenarios using CTMs and assessing their impacts on population exposure. One drawback of these models is their coarse spatial resolution (typically in the order of several Kilometers), which fails to capture the large intraurban variabilities in air pollution concentrations.…”