Sulfur Dioxide | Wisconsin Department of Health Services
Sulfur dioxide, SO2, is a colorless gas or liquid with a strong, choking odor. It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores (aluminum, copper, zinc, lead, and iron) that contain sulfur. Sulfur dioxide dissolves easily in water to form sulfuric acid. Sulfuric acid is a major component of acid rain.