The methodology and sources of data for the program are described in detail in the report, Size Specific Total Particulate Emission Factors for Mobile Sources, prepared in August, 1984 for EPA by EEA. The report describes the calculation of particulate emission factors for each of the six vehicle classes used in the program. It also provides emission factors for each major type of particulate (lead, organic, sulfate, and diesel composite). The program inputs and format are designed to parallel those found in MOBILE 3. User inputs include scenario year, vehicle speed, driving conditions, and particle size range. By setting control flags the user can elect to replace the default data with locality specific data...Software Description: The program is written in the FORTRAN programming language for implementation on an Amdahl 5860 computer using the MTS operating system.