FIGURE 2—

Adjusted Mean Difference in PM_2.5 Concentrations Between American Indian (AI)- and Non–AI-Populated Counties That Are (a) Modeled, and (b) Measured: 2000–2018

Note. PM2.5 = fine particulate matter. The solid line shows the effect estimates (county type coefficient + interaction coefficient with time) of being classified as an AI-populated county over the study period. The dashed lines show the 95% confidence intervals from model 4. The red line represents no difference in adjusted average PM_2.5 concentrations between AI and non–AI-populated counties.