As additional points of comparison for our modeled results, we examined datasets of finely resolved satellite observations and empirical model predictions. These datasets afford the ability to consider changes in exposure and disparity for the entire state (see Supplementary Text) . In Fig. , we compare our analyses with changes in total PM2.5 (only moderately influenced by vehicles) and NO2 (strongly influenced by vehicles). Considering PWM concentration changes from 2000-2019, our estimated PWM PM2.5 from on-road vehicles declined at a broadly similar rate (~65%) compared to the results from a high-resolution empirical model of PWM NO2 spatial patterns (~55%). Our estimates of the racial-ethnic ordering of vehicle-emitted PM2.5 exposures and disparities closely match that from the total PM2.5 and NO2 datasets. Crucially, our finding of temporally persistent relative disparities in exposure to PM2.5 from on-road sources (Fig. ) is consistent with highly stable patterns of relative disparity in total PM2.5 and NO2 for Californians of color (Fig. ). Furthermore, we find that the magnitude of our estimate of traffic-related PWM PM2.5 is consistent with the on-road vehicle contribution from previous modeling and in-situ source apportionment studies in California . In combination, these supporting lines of evidence reinforce our key qualitative conclusion that exposures from mobile sources have decreased while relative disparities in exposure have persisted.