The U.S. nonferrous metals production industry is a significant contributor of sulfur dioxide, trace metal, and particulate air emissions. Most of the domestic copper smelting capacity is based on obsolescent technology that is both capital-and energy-intensive and hampered by considerable emission control problems. Because systems used to control sulfur dioxide emissions also must remove particulate contaminants, effective control of total particulate and trace element emissions is accomplished as a 'byproduct' of sulfur dioxide control. The sulfuric acid plant, when it can be operated under autothermal conditions, is recognized as the technology of choice for controlling sulfur dioxide emissions from smelters. Unfortunately, much of the problem of sulfur dioxide control in the nonferrous industry is associated with the weak sulfur dioxide off-gas streams. Because weak sulfur dioxide streams do not permit autothermal acid plant operation, they cannot be economically controlled by acid plant technology. In copper smelting, the major sources of weak sulfur dioxide off-gases are the reverberatory furnace and multihearth roaster, followed by fugitive emissions that emanate from the converter operation, matte tapping, slag tapping, and ladle transfer. The status of development and use of a number of technologies for wet scrubbing and for process changes based on oxygen smelting technologies were evaluated to determine which could be considered promising candidates for near-term application for sulfur dioxide control at domestic smelters. Cost models were developed for those processes believed to be sufficiently promising for such application.