The Protocol to the Convention on Long-range Transboundary Air Pollution on the Financing of the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) was entered into force in 1988. Forty-six ECE countries are currently Parties to this Protocol. It is an instrument for international cost-sharing of a monitoring programme which forms the backbone for review and assessment of relevant air pollution in Europe in the light of agreements on emission reduction. EMEP has three main components: collection of emission data for SO2, NOx, VOCs and other air pollutants; measurement of air and precipitation quality; and modelling of atmospheric dispersion. At present, more than 200 monitoring stations in 40 ECE countries participate in the programme.