Sulphur Dioxide (SO2) is produced when a material, or fuel, containing sulphur is burned. Globally, much of the sulphur dioxide in the atmosphere comes from natural sources, but in the UK the major contributors are power stations (65% of the total emissions). Sulphur dioxide pollution episodes only generally occur where there is widespread domestic use of coal or in the vicinity of coal-fired or oil-fired power stations.
Exposure to the highest concentrations in outdoor air is unlikely to have an effect on the well-being of healthy persons. However those suffering from asthma or other breathing problems are much more sensitive to SO2. Effects on peoples breathing, particularly in these sensitive groups, happens soon after exposure to the pollutant. Short-term exposure to high levels of sulphur dioxide may cause coughing, tightening of the chest and irritation of the lungs.