Fine particulate matter emissions from electric vehicle fast charging stations

The global shift to electric vehicles necessitates the expansion of Direct Current Fast Charging (DCFC) stations, yet the related environmental and public health impacts remain unclear. Here, we report that the power cabinet at DCFC stations emit fine particulate matter (PM_2.5). We collected integrated filter samples from 50 DCFC stations across 47 cities in Los Angeles County, California. The daily PM_2.5 concentrations were between 7.3 and 39.0 µg m^-3, significantly higher than urban background sites (p = 0.02) and the nearest U.S. EPA monitoring stations (p < 0.0001). To understand the emission mechanism of these particles, we measured real-time PM_2.5 mass concentration, particle size distribution, and other pollutants, as well as characterized particle chemical compositions on integrated filter samples. Our results indicate that these particles, primarily in the sub-micrometer range (0.5-1.0 µm), are likely due to particle resuspension from the power cabinets. PM_2.5 samples from power cabinets showed higher levels of brake and tire wear tracers (Ba, Cu, Zn) and dust tracers (Ca, Al, Fe) compared to samples from nearby chargers and background sites. With no current emission standards for DCFC, managing particle resuspension is crucial for improving air quality and protecting public health as transportation electrification advances.