SMOKE can accommodate a variety of chemical mechanisms for the models it supports. From the emissions processing perspective, the chemical mechanism is the mapping of the pollutants provided in the emissions inventory to the species needed by the AQM of interest. For example, the input files for five chemical mechanisms for the CMAQ model are available for download from the EPA; these mechanisms are Carbon Bond 4 (CB4), CB4 with particulates, Regional Acid Deposition Model, 2 (RADM2), RADM2 with particulates, and a research version of CB4 with toxics.

In Section 4.5.10, “Use a different speciation mechanism or change speciation inputs”, we provide the settings needed in the Assigns file to use a different chemical mechanisms with SMOKE. SMOKE is not constrained to the files available for download. If you need to process other data (e.g., a tracer species) with SMOKE, they can be added to several input files, including the chemical mechanism file, to be output to the AQM. Some additions to chemical mechanisms are easier than others, and we explain how to determine whether you can create the files you need for your situation. We also give instructions on how to add species to the chemical mechanism files and how to make sure that the inventory pollutants are mapped to the correct chemical species.

SMOKE users must know what chemical mechanism will be used in the AQM for which the SMOKE output emissions are intended. Once that has been determined, the following files must be configured to be consistent with the inventory being used and the chemical mechanism: the inventory table (INVTABLE), speciation profiles (GSPRO), speciation cross-reference (GSREF), and the mobile processes file (MEPROC) when creating on-road mobile emissions with MOBILE6 through SMOKE.