Sulfur dioxide (chemical formula SO2) is the most common, simplest, and irritating sulfur oxide. One of the major air pollutants. The gas is ejected during volcanic eruptions, and sulfur dioxide is also produced in many industrial processes. Since coal and oil usually contain elemental sulfur, sulfur dioxide is formed when burned. When sulfur dioxide dissolves in water, sulfurous acid is formed. If sulfurous acid is further oxidized in the presence of PM2.5, sulfuric acid (the main component of acid rain) will be formed quickly and efficiently. SO2 gas analyzer refers to an instrument that continuously and automatically measures sulfur dioxide in the atmosphere, which is an air pollution analyzer. Commonly used detection methods include solution conductivity method, flame photometry, coulometric method (coulometric method) and ultraviolet fluorescence method.