Definition

Oxides of sulfur (SOₓ) are a group of chemical compounds composed of sulfur and oxygen that are released into the atmosphere through natural processes and human activities. The most common forms in ambient air are SO₂ and SO₃. SO₂ is a major air pollutant primarily produced by the combustion of sulfur-containing fossil fuels and industrial processes. In the atmosphere, SO₂ can undergo chemical reactions to form other sulfur compounds and contribute to particulate matter and acid deposition.