This Directive makes provision to reduce emissions of certain pollutants into the air from large combustion plants. The Directive applies to combustion plants, the rated thermal input of which is equal to or greater than 50 MW, regardless of the type of fuel used (solid, liquid or gaseous). For the purposes of these provisions, "combustion plant" means any technical apparatus in which fuels are oxidized in order to use the heat thus generated. Article 2 (7) specifies those combustion plants which shall not fall within the application scope. Member States shall draw up appropriate programmes for the progressive reduction of total annual emissions from existing plants. The programmes shall set out the timetables and the implementing procedures (art. 3). Annexes I and II fix ceilings and reduction targets for emissions of So2 and nox from existing plants, whilst Annexes III to VII establish emission limit values. Annex VIII describes the methods of measurement of emissions.