Chicago geography and simulated pollutants. (a) Neighborhoods and highways within the city of Chicago. Inset at lower left depicts the location of Chicago (black) within the 1.3 km domain. In the right column, we provide annualized WRF-CMAQ simulated (b) NO2, (c) O3, and (d) PM2.5 concentrations over Chicago and average concentrations within city limits (μ).