The document has been published by the U.S. Environmental Protection Agency (EPA) since 1970. Supplements to AP-42 have been routinely published to add new emissions source categories and to update existing emission factors. An emission factor is an average value which relates the quantity (weight) of a pollutant emitted to a unit of activity of the source. The uses for the emission factors reported in AP-42 include: Estimates of area-wide emissions; Emission estimates for a specific facility; and Evaluation of emissions relative to ambient air quality. The EPA routinely updates AP-42 in order to respond to new emission needs of State and local air pollution control programs, industry, and the Agency itself. Section 1.7 in AP-42, the subject of this Emission Factor Documentation (EFD) report, pertains to lignite combustion in stationary, external equipment. The last comprehensive update of AP-42 Section 1.7 was in 1982, focusing on uncontrolled, baseline, emission factors for the criteria pollutants. The section was appended in 1986 with data on particle sizing distributions. The purpose of the present effort on AP-42 Section 1.7 is to update the data base for the earlier revisions and to extend the scope to other pollutant species and revised equipment classifications