Nitrogen oxides in the atmosphere are known to have many adverse effects upon health and welfare, and reduction of emissions of these pollutants is of prime importance to any effective air pollution abatement program. This document has been prepared to summarize current information on nitrogen oxide air pollutants--sources and methods of control. Nitrogen oxides originate from a variety of sources, and the emissions vary widely in physical and chemical characteristics. The many agricultural, commercial, domestic, industrial, and municipal sources of these air pollutants are described individually in this document. The nature and quantities of the emissions from the various processes are discussed, and methods of control that have been successfully applied are listed. The control techniques described herein represent a broad spectrum of information from many engineering and other technical fields. A tabulation of emission factors from which overall emissions for the various sources can be estimated is presented.