The Consolidated Mining and Smelting Company (renamed Cominco in 1966) was formed in 1906 and four years later bought the Sullivan Mine, the world’s largest silver-lead-zinc ore body, located at Kimberley in the southeast corner of the Canadian province of British Columbia, which borders on the American states of Washington, Idaho, and Montana. The complex sulfi te ore was shipped to the company’s newly acquired and redesigned smelter in Trail, B.C., some 160 km to the southwest in the Columbia River valley. As the lead and zinc concentrates contained from 17-33% sulfur, their smelting produced signifi cant quantities of sulfur dioxide as a waste product that was off-gassed from a 409-foot tall stack. By 1930, these releases had reached a high of 651 tons per day of SO 2 (or 325.5 tons as sulfur).