We evaluate PWM PM2.5 exposure from on-road mobile sources for racial-ethnic groups and residents of overburdened communities (Fig. ). Our modeled estimate of PM2.5 declined for all groups, and the ordering of exposures by group is generally consistent over time. Among all racial-ethnic groups, Hispanic Californians experienced the highest exposure for all years, with PWM exposure concentrations of approximately 3.5 and 1.3 μg/m 3 PM2.5 in 2000 and 2019, respectively. Black Californians experienced the next highest PWM exposure concentration (respectively 3.5, 1.2 μg/m 3 in 2000 and 2019), followed by Asian Californians (3.3, 1.2). Of the four racial-ethnic groups in Fig. , white Californians were exposed to the lowest PWM concentrations: approximately 2.7 and 0.9 μg/m 3 PM2.5 from 2000 and 2019, respectively.