Sulfur Dioxide

Sulfur dioxide (SO₂) is a non-flammable, colorless gas with a strong odor; similar to the smell of a just-struck match. At higher concentrations, SO₂ can be tasted and produce an irritating odor. One-third of the total emissions of sulfur compounds into the atmosphere come from human-made sources. SO₂ is primarily emitted from power plants and refineries that burn fossil fuels (coal and oil), along with the smelters, pulp, paper, and steel mills.

While volcanic eruptions naturally emit significant amounts of sulfur dioxide into the atmosphere, the particles can also be released by the decay of organic matter or in sea spray. Sulfur dioxide can react with substances in the atmosphere to create acid rain.

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