How does sulfur dioxide form during the burning of sulfur-containing fuels?

Sulfur dioxide ($S{O}_2$) forms during the combustion of sulfur-containing fuels—such as coal and oil—when the sulfur compounds present in these materials react with oxygen.12

During the process of combustion, the sulfur atoms within the fuel oxidize, resulting in the release of sulfur dioxide gas. This chemical reaction is a significant contributor to air pollution in industrial regions, as the gas is emitted into the atmosphere where it can further contribute to the formation of acid rain. Because sulfur dioxide is harmful to both the environment and human health, efforts to mitigate its impact often focus on the difficult and expensive process of removing sulfur from fossil fuels before they are burned.13