Our observations show a substantially expanded range of exposure -both between and within neighborhoods -than census block-level NO2 predictions from a national-scale predictive model similar to a land use regression (year-2015 integrated empirical-geographic [IEG] model) . The national IEG modeled estimates (Figure , gray overlaid plots) show a ratio of 1.6 between highest and lowest neighborhood median exposure compared to 4.6 from mobile monitoring, and a totalpopulation IQR of 2.2 ppb (IEG) compared to 6.1 ppb from mobile monitoring data (SI Appendix, Fig ). This result suggests that the national IEG model may miss some localized influences and may underestimate total population disparity and, by extension, the potential range of health risks. We find that the IEG model predicts higher median and mean exposure (2.8 ppb [36%] and 2.5 ppb [30%] higher, respectively) across the total population, compared to mobile monitoring data. No NO, BC, or UFP data at the same spatial resolution were publicly available at the time of this analysis . Systematically higher concentrations for Black and Hispanic groups driven by regional variation.