The CIT air quality model with aerosol modeling capability and its associated components are used to understand causes of ozone and particulate matter exceedances in the Houston-Galveston area. In order for this modeling system to gain increasing acceptance and use in guiding air quality management, it is important to assess how transportable this modeling system is across geographic domains. We describe the application of this modeling system to evaluate the performance and to assess its sensitivity to emission control options in the Houston-Galveston area. The model's response to emission control options is consistent with other models of the same genre.