Sulfur oxides are chemical compounds of sulfur and oxygen in the form S X O Y with lower members of the family being S 7 O 2 and higher being as SO, SO 2 and SO 3 . While natural sources of sulfur oxides include volcanic eruption emissions, the chemical compound is released chiefly through the combustion and processing of sulfur containing fuels and ores. Sulfur is an impurity found in most fossil fuels such as coal and oil, encompassing a content of sulfur between 0.5–3 percent and 0.5–5 percent, respectively. Large-scale energy production associated with industrialization has established sulfur oxides as one of the prime anthropogenic air pollutants. Coal and oil contain trace impurities of sulfur. When they are burned they produce sulfur oxides, mostly sulfur monoxide SO and sulfur dioxide SO2 and sulfur trioxide SO 3 , at the same time.