Sulphur dioxide (SO2)

A gas released from volcanoes and certain fossil fuel combustion. Sulphur dioxide combines with particulate matter to produce smog, contributes to acid rain, and can make sea- and freshwater more acidic. Sulphur dioxide can have negative health impacts particularly for people with lung disease like asthma. Sulphur dioxide can combine with water in the atmosphere to produce an aerosol which reflects sunlight, having a cooling effect.