||This document has been prepared to summarize the latest information on nitrogen oxide pollutants--their sources and methods of control. The term nitrogen oxide (NOx) refers to two gaseous nitrogen oxides, nitric oxide (NO) and nitrogen peroxide (NO2). These pollutants are created by the combustion of fossil combustibles or the fabrication and utilization of nitric acid. Mobile sources contribute more than 40% of all nitrogen oxide emissions produced by man in the United States. Approximately 40% of nitrogen oxide emitted by stationary installations is attributed to the production of electric energy. Other agricultural, commercial, household, industrial, and municipal sources are studied individually in this document. Methods of control against nitrogen oxide emissions can be classed in two broad categories: those reducing or preventing the formation of NOx and those which extract NOx from emitted gases. The former category applies particularly to the combustion of fossil combustibles, and implies a modification of the combustion process. The methods of the second category are applicable for both the combustion process and chemical treatments, but the best results have been obtained for exhaust gas by chemical treatments. The nature and the quantities of emissions produced by different types of treatments are discussed, and the methods of control of these emissions which have given satisfactory results are enumerated. Emission factors can be used to estimate the emissions for sources for which exact experiments are not possible. Emission factors for treatments of certain source-types are presented in Chapter 5. Tables, graphs, diagrams, extensive references.