sulphur dioxide (SO2)

Sulphur dioxide is a colourless gas with a sharp and irritating odour. It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulphur.

When SO2 combines with water, it forms sulphuric acid, which is the main component of acid rain. When acid rain falls it can cause deforestation, acidify waterways to the detriment of aquatic life and corrode building materials and paints.


SO2 can affect the respiratory system, the functions of the lungs and irritate the eyes. When SO2 irritates the respiratory tract it causes coughing, mucus secretion, aggravates conditions such as asthma and chronic bronchitis and makes people more prone to respiratory tract infections. SO2 can attach itself to particles and, if these particles are inhaled, they can cause more serious effects.