SO2 measurement
Gaseous air pollution

Sulfur dioxide SO₂ is a weakly acidic gaseous compound, emitted into the atmosphere during the combustion of products containing sulfur in varying proportions: biomass, oil, coal. It gradually oxidizes in the atmosphere and leads, in the presence of water, to sulfuric acid, the major culprit in atmospheric acidity and respiratory irritation. SO ₂ is a respiratory irritant but, at usual atmospheric concentrations, it is above all its oxidation derivative, sulfuric acid, that presents environmental risks. The responsibility of SO ₂ in air pollution has been identified for over 50 years, and it has long been measured in urban atmospheres, by an indirect indicator, "strong acidity". Today it is measured specifically.