Artikel 18 Protocol bij het Verdrag van 1979 betreffende grensoverschrijdende luchtverontreiniging over lange afstand inzake de verdergaande vermindering van zwavelemissies

18 In general, standards are set, per emission source, according to plant size, operating mode, combustion technology, fuel type and whether it is a new or existing plant. An alternative approach also used is to set a target for the reduction of total sulphur emissions from a group of sources and to allow a choice of where to take action to reach this target (the bubble concept).