The amendments to the Clean Air Act require states to develop '...comprehensive, accurate, and current...' inventories of each pollutant from all sources for every non-attainment area, in conjunction with the preparation of revised State Implementation Plans (SIPs). To assist states in meeting the Clean Air Act requirements for emission inventory development, EPA has prepared a five-volume series that describes in detail many of the technical aspects of the inventory process. The document is the fourth volume in the series, and it focuses on mobile sources. Specifically the document presents detailed methods that can be used to identify sources, estimate emissions, and establish and maintain a useful, current mobile source emissions inventory. Special attention has been given to preparing the 1990 SIP inventories. Individual chapters present specific methods that should be used to derive emission estimates for each of the primary mobile source subcategories, which include highway vehicles, nonroad sources, aircraft, and locomotives.

Cover title. Document number was not updated for revised version, but should be EPA420-R-92-009 based on NEPIS copy.