The NOAA Eta-CMAQ modeling system's capability to accurately forecast concentrations of particulate matter with a focus on the accumulation mode particles has been tested. This effort is in line with NOAA's commitment to provide PM2.5 (particles less than 2.5 microns in median diameter) forecast for the nation within the coming years. The particulate matter forecasts are quantified by the predictions of number concentration, the speciation of the particulates and its associated air quality in terms of its light scattering characteristics (e.g., visibility). It is expected that the evaluation of these test runs might provide information on the various sources of uncertainties such as precursor emissions, initial conditions, chemistry, physics, and transport that might lead to uncertainties in predictions of PM2.5 and Aerosol Optical Depths (AODs). Verification of model predicted aerosol concentration will be conducted by using EPA's hourly averaged surface level PM2.5 measurements. On the other hand, the model predictions of AODs will be verified using NOAA's near real time aerosol optical depth retrievals from GOES imager obtained at 30-minute interval at 4 km X 4 km spatial resolution.