Publisher Summary This chapter focuses on point sources of air emissions within different types of plant operations, along with the methods of abatement. The three processes for the manufacture of chlorine and caustic soda from brine include the mercury cell, the diaphragm cell, and the membrane cell. Caustic scrubber systems should be installed to control chlorine emissions from condensers and at storage and transfer points for liquid chlorine. Nitrophosphate fertilizers are also produced by the mixed-acid process, through digestion of the phosphate rock by a mixture of nitric and phosphoric acids. Air emissions at point of discharge should be monitored continuously for fluorides and particulates and annually for ammonia and nitrogen oxides. The major industrial processes within the petroleum refining industry, including the materials and equipment used, and the processes employed are described in this chapter. Some of the major supporting processes include waste water treatment, gas treatment, and sulfur recovery. The air pollution from iron and steel manufacturing is also elaborated.