Globally, much of the sulphur dioxide in the atmosphere comes from natural sources, but in the UK the major contributors are power stations (65 per cent of the total emissions). Sulphur dioxide levels in this country have dropped considerably over recent years due to cleaner power stations and a decreased use of coal.

The highest levels of sulphur dioxide are recorded in areas where coal is used extensively. Sulphur dioxide pollution episodes only generally occur where there is widespread domestic use of coal or in the vicinity of coal or oil-fired power station.

Short-term exposure to high levels of sulphur dioxide may cause coughing, tightening of the chest and irritation of the lungs.