What is SOx? Environmental Impacts SOx Sources Emissions Reduction Efforts New Technologies
	This Mount St. Helens, Washington. Sunset on Mount St. Helens, as seen from the south, April 26, 2005.
	According to the EPA, SO2 emissions come from a variety of industrial sources including electrical utilities.

What are the major sources of sulfur oxides in the world and the United States?

Sulfur oxide emissions come from two sources: nature and human industry.

Natural Sources
Volcanic eruptions and other natural sources account for roughly 25% of the total sulfur added to the atmosphere in an average year. Volcanic emissions occur in areas all over the world. In fact, in 2004 Mount St. Helens in Seattle, WA, was "pumping out between 50 and 250 tons a day of SO₂. All the State's industries combined only produced about 120 tons a day."

Anthropogenic (Human-Made) Sources
A majority of human sources of emissions are in the northern hemisphere. Emissions, however, vary greatly geographically. Much of the human generated sulfur oxide emissions originate in Asia, where coal-fired power generation has increased dramatically – particularly in China. However, the Chinese government announced sweeping new air quality regulations in 2000 and has made control of pollution emissions from these facilities a priority.

The U.S. Government estimates that the U.S. accounts for only 12% of worldwide SO₂ emissions, most of which come from electrical utilities with the remainder from other industry. However, SO₂ emissions have decreased by over 50 percent in the US since enactment of pollution emission limits in 1970. And limits are projected to be at less than half of current levels by 2015.

The chart below shows the distribution of SO₂ emissions across the world.

Sources Of Global Sulfur Dioxide Emissions - Year 2000 -
(Source: Compiled from World Resources Institute's Earthtrends website.