The Large Combustion Plant Directive aims to reduce emissions of sulphur dioxide, nitrogen oxides and dust particles from large combustion plants such as power stations, petrol refineries and steelworks. It applies to combustion plants with a thermal output greater than 50MW.

Suplur dioxide, nitrogen oxide and dust particles are major contributors to acid deposition which damages plants and aquatic habitats by acidifying soils and freshwater, and corrodes buildings.

A Europe wide approach was required to tackle this problem as these pollutants can travel long distances before being deposited, so the polluter is unlikely to suffer the consequences of their own polluting behaviour.

The directive sets limits to emissions. All new combustion plants must meet specified emission limit values. Existing plants, in operation prior to 1987 when the original directive was introduced, can either comply with these emission limit values, or operate within a 'National Plan' produced by the member state which sets out a national total level of emissions.