SO₂ is emitted by Teck Trail Operations as a by-product of processing mine concentrates, which contain sulphur, into metal and chemical products. With environmental improvements, SO₂ emissions continue to decline. Teck Trail Operations currently captures more than 99% of the sulphur and converts it to by-products, such as fertilizer and sulphuric acid. About 1% leaves the operation through emissions to air. Sulphur capture at Teck Trail Operations is similar to what you might find at a brand-new smelter. However, the dispersion of air emissions from the smelter is constrained due to the location of the smelter, weather and the surrounding topography. SO₂ levels in Trail are not static and fluctuate throughout the day, month and year. See docs 7 and 8 for more information on SO₂ levels.