Annual emissions inventory is one means used by the states to assess the level of pollutants released into the air from various sources. The source categories are point, area/non-road, on-road, and biogenic sources. Emissions inventory can be utilized for chemical transport modeling when it is preprocessed using emission processing models (SMOKE, EPS2) to spatially and temporally allocate source emissions into corresponding grids. The Center has investigated 1996, 1999, and 2002 national emissions inventory (NEI) to provide grid emissions input for chemical transport modelings. The Center is also evaluating global speciated Mercury emissions in cooperation with Argonne National Laboratory as part of a detailed study evaluating mercury deposition and transport.