How is sulphur dioxide (SO2) measured?
Sulphur dioxide is usually measured automatically, by a continuous analyser that uses ultra-violet fluorescence. The concentration of sulphur dioxide is calculated by measuring the fluorescent radiation energy produced when the sulphur dioxide molecules are bombarded by UV radiation inside the analyser. This then provides a concentration in air, usually expressed in parts per billion (ppb) or micrograms per cubic metre (µg m-3).
