Air quality, health and equity impacts of transport electrification in the U.S. Midwest. 

Chronic traffic related air pollution (TRAP) exposure is linked to various adverse health outcomes including pediatric and adult asthma incidence, but more importantly can also lead to premature mortality. In the U.S., the majority of people living close to high volume and density roadways are people of color who are exposed to disproportionate levels of associated health harming primary and secondary air pollutants such as NOx (NO + NO2; key precursors for O3 formation) and PM2.5 as well as greenhouse gases (e.g. CO2). Both heavy- and light-duty vehicles (HDVs/LDVs) contribute to on-road TRAP but on a per vehicle basis, the associated air quality and public health impacts are larger for HDVs. One potential climate mitigation strategy is the shift of the transportation sector to battery powered alternatives (EVs). However, the associated air quality, health and equity implications of such a transition are not well understood and lack characterization at fine intra-urban spatial scales. Given non-linear atmospheric chemistry associated with the formation of secondary pollutants (e.g O3), and the steep spatial gradients exhibited by short lived TRAP (e.g.  NO2), here we use the two-way coupled Weather Research Forecast and Community Multiscale Air Quality (WRF-CMAQ) chemical transport model at 1.3 km to determine changes in simulated NO2, O3 and PM2.5 concentrations from the electrification of 30% of HDVs and LDVs over a central U.S. Midwestern domain. We represent changes in on-road, refueling and idling emissions as well as power plant emissions from the increased electricity demand needed for charging. Altered emissions are then used as inputs to run a month-long simulation for each season. Incorporating high resolution concentration changes with census tract level health data, we estimate changes in health impacts at the census tract level and across different population subgroups. We find that electrifying 30% of primarily diesel-fueled HDVs reduces NOx emissions by a factor of 10 for each vehicle mile compared to the NOx reductions associated with electrifying 30% of LDVs. We simulate domain-wide annual mean NO2 (~-10%) and PM2.5 (~-2%) reductions that peak along major roadways, however MDA8O3 concentrations increase in urban cores. If 30% HDVs and LDVs are electrified, we estimate that 1,120 and 170 annual premature deaths linked to NO2 and PM2.5 would be avoided, respectively while 80 annual premature deaths associated with MDA8O3 would be added. Additionally, we find that the largest simulated air quality and health benefits are within communities of color. Notably, we find that while the domain as a whole is only 12% Black, communities with the largest NO2-related health benefits are 45% Black.    Our results demonstrate that incentives aimed at reducing transportation related emissions, especially from HDVs, are beneficial from a climate perspective but also from an air quality, health and economic perspective with the potential to reduce long standing environmental injustices.