The report has been prepared to provide reliable information on atmospheric emissions from sulfuric acid manufacturing plants and on method and equipment normally employed to limit these emissions to satisfactory levels. Background information is included to define the importance of the sulfuric acid industry in the United States. Basic characteristics of the industry are discussed, including growth rate in recent years, types of raw materials used, end uses for the product, and the number of producing establishments, i.e. manufacturing sites, in existence during the past and at the present time. Process descriptions are given for the two processes in commercial use: the contact process and the chamber process. Process information includes discussions of the normal process variables that affect the types and quantities of emissions, the normal range of emissions, startup and shutdown losses, and methods of emission control and recovery. Supplemental material provides detailed descriptions of sampling and analytical methods. Emissions to the atmosphere from a sulfuric acid plant depend upon a number of factors, such as design of the plant, skill of operation, efficiency of the catalyst, completeness of recovery operations, and the use of special devices to reduce emissions.