MIDAS-AT’s urban and dispersion model is vital for any emergency management team. Standard hazard prediction plume models ignore building shapes and the canyon-like nature of major city streets making their predictions useless. Other models assume the world is flat: our Urban Model in MIDAS-AT explicitly models building shapes to give users a prediction that is representative of the operational environment of the terrorist attack. The Urban Model takes into account a city's physical features, which will have an impact on the flow and deposition of a toxic substance.