TWENTY-FIVE YEARS OF EFFECTS RESEARCH FOR THE CONVENTION ON LONG-RANGE TRANSBOUNDARY AIR POLLUTION Matti Johansson 1 , Heinz Gregor, Beat Achermann, Fred Conway, Régis Farrett, Martin Forsius, Harry Harmens, Thomas Haußmann, Jean-Paul Hettelingh, Alan Jenkins, Tor Johannessen, Michal Krzyzanowski, Vladimir Kucera, Berit Kvaeven, Martin Lorenz, Lars Lundin, Wojciech Mill, Gina Mills, Maximilian Posch, Brit L. Skjelvkvåle, Till Spranger, Merete J. Ulstein, Keith Bull 2 The Extended Bureau of the Working Group on Effects, c/o Secretariat for the Convention on Long-range Transboundary Air Pollution, Environment and Human Settlements Division, United Nations Economic Commission for Europe (UNECE), Palais des Nations, CH-1211 Geneva, Switzerland 1 Author for correspondence, e-mail Matti.Johansson@unece.org 2 Presenting author ABSTRACT Concerns on the harmful effects of air pollutants in 1970s prompted international collaboration to combat air pollutants at their sources. The Convention on Long-range Transboundary Air Pollution was established in 1979, with subsequent setup of its working bodies. They included the Working Group on Effects, which laid the basis for the cooperative monitoring and research of air pollution effects. This group comprises several international cooperative programmes and task forces. They cover a variety of receptors from ecosystems (forests, surface waters, vegetation) to materials and health effects on populations, including mapping activities and integrated monitoring. The research addresses many interlinking environmental problems and causative pollutants: acidification, terrestrial eutrophication, health effects, corrosion, ozone, particulate matter, contamination by heavy metals and persistent organic pollutants. The observational and modelling results cover the geographical area United Nations Economic Commission for Europe (UNECE) and the recorded trends span more than 15 years. The effect-oriented work has initiated and supported the development of several air pollutant emission reduction protocols under the Convention, some based on effects-based model calculations. The cooperation has created a nexus of observational networks and interdisciplinary policy-linked research unique in the world. 1 INTRODUCTION The 1979 Convention of Long-range Transboundary Air Pollution [1] established a broad framework for the UNECE region (of Europe, Central Asia and North America) to work cooperatively addressing the transport of pollutants through the atmosphere and over borders, oceans and continents. The Convention entered into force in 1983 and now has 49 Parties including the European Community. It has been extended by eight specific protocols, of which seven are in force. The Convention and its protocols identify the need for Parties to carry out research and development, to exchange scientific and technical information and to take part in monitoring programmes. To promote such activities the Convention has