The Protocol to abate acidification, eutrophication and ground-level ozone (Gothenburg Protocol) was adopted in 1999 by the Parties to the Convention on Long-Range Transboundary Air Pollution (CLRTAP).


It entered into force in 2005 and sets emission ceilings for 2010 for four air pollutants: sulphur, nitrogen oxides, volatile organic compounds and ammonia.

It also sets emission limit values for the key source categories (stationary, mobile and products).


The Gothenburg Protocol was amended in 2012 to include national emission reduction commitments to be achieved in 2020 and beyond.


Several of the annexes containing emission limit values to be adhered to by Parties were revised with updated sets of emission limit values and emission ceilings for fine particulate matter were added.


The source-related annexes mostly cover combustion plants over 50 MW, but for some categories the threshold is lower than 50 MW. These in brief are:


- Annex IV: limit for sulphur content of gas oil: <0.1% by January 2008 (transposed in EU legislation via Directive 1999/32/EC);


- Annex V (NOx): limit values for new stationary engines (gas engines and dual fuel engines greater than 1MW and diesel engines greater than 5MW): limits vary between 95 and 225 mg/Nm³ (15% O2) depending on the engine type and fuel used; exemptions may be granted for plants running less than 500 hours per year or plants used in particular local conditions;


- Annex X (dust): non-binding emission levels for solid and liquid fuel fired boilers and process heaters between 1 and 50 MW: these levels vary between 20 and 50 mg/Nm³ ("dust" is a term used in Annex X, Part A of the Gothenburg Protocol (as amended in 2012) in the context of particular matter emissions, with the following explanation given: "In this section only, "dust" (...) means the mass of particles, of any shape, structure or density, dispersed in the gas phase at the sampling point conditions which may be collected by depending on the size and plant age (at various reference oxygen contents, depending on the fuel type).


Compliance with the emission limit values is not the only compliance option for Parties. Alternatively 'different emission reduction strategies that achieve equivalent overall emission levels for all source categories together' may be applied.


The Protocol nevertheless requires that, 'Each Party should apply best available techniques (...) to each stationary source covered by [the] annexes[...] , and, as it considers appropriate, measures to control black carbon as a component of particulate matter[...]. 


Source: Medium Combustion Plants Directive Impact Assesment Document, p. 310