Sulfur oxide emissions from the non-ferrous metals industries are causing ambient air quality standards to be exceeded in four locations in Montana and Utah. The objective of this plan is to insure that the national ambient air quality standards will be achieved by May 30, 1975. The means to this end are described specifically in each of the six tasks. The tasks are a step-wise procedure for proceeding to the end objective. Fulfillment of Task 1 will establish the basis for development of control regulations. Tasks 2 and 3 will proceed in parallel; completion of these tasks will result in definition of what controls each smelter will have to meet by May 30, 1975. Task 4 is envisioned to provide the EPA with the determination of whether or not there are acceptable alternatives to permanent emissions controls. Task 5 will provide the mechanism for monitoring the ambient air quality around each smelter to determine if air quality standards will be met. Task 6 will provide the 'watch dog' aspects of the entire plan.