EPA has established a National Ambient Air Quality Standard (NAAQS) for nitrogen dioxide (NO2) at a level of 100 ppbv (188.7 μg/m3) averaged over a 1-h period. When EPA or a state regulatory air agency issues a New Source Review (NSR) construction permit for major sources of air pollution, one of the permitting requirements is an air quality impact analysis that demonstrates compliance with the NAAQS. The air impact analysis is performed using EPA-approved air quality dispersion models such as the AERMOD model. AERMOD is a steady-state Gaussian plume model that contains algorithms to simulate plume rise and turbulent atmospheric mixing and dispersion processes.