Persistent Near-Roadway Air Quality Disparities in California Despite Widespread Zero-Emission Vehicle Adoption

The adoption of zero-emission vehicles (ZEVs) offers multiple benefits for the climate, air quality, and public health by reducing tailpipe emissions. However, the environmental justice implications of the non-exhaust emissions from future ZEV fleets for near-roadway communities remain unclear. Here, we model the on-road fine particulate matter (PM2.5) emissions across all California counties and assess the near-roadway exposure disparities at the census block group level in Los Angeles County in 2050, when almost all passenger vehicles are projected to be ZEVs. We found that although heavy-duty trucks (HDTs) represent only 7% of on-road traffic in LA County, ZEV policies targeting HDTs provide more benefits than those aimed at light-duty vehicles (LDVs). In both the state and LA County, ZEV promotion in HDT fleets generates more favorable benefits for disadvantaged communities compared to LDV fleets. In LA County, the most disadvantaged 25% of the population experiences 36% and 44% of the total environmental benefits from promoting zero-emission LDVs and HDTs, respectively, which is 2.4 and 3.7 times higher than the benefits shared by the least disadvantaged quantile. Despite the progress in benefiting marginalized populations through ZEV promotion, disparities persist due to the remaining brake and tire wear emissions and increased HDT traffic in disadvantaged communities. We recommend implementing fleet-specific ZEV policies to address brake and tire wear emissions, as well as optimizing freight structures, to address these persistent environmental justice issues in California.