In 1969 the North Atlantic Treaty Organization (NATO) cstablishcd thc Committee on Challenges of Modern Society (CCMS). The subject of air pollution was from the thc very beginning one of the priority problems umier deliberation within the tJ-amcwork of various pi- lot studies undertaken by this committee. The organization of a yearly conference dealing with air pollution modelling and its application has become one of the main activities within thc pilot study rclating to air pollution. Pleasc see the listing on the next page for completed NATO/CCMS Pilot Studies and the International Technical Meetings (ITM) on Air Pollution Modelling and Its Application. This volume contains the papers at the 22ND lTM, being held in Clermont-Ferrand, France during June 2 -6,1997. It was attended by 152 participants representing 33 countries. This lTM wasjointly organized by the Ris0 National Laboratory of Denmark (pilot country): the Laboratoire Associe de Meteorologic Physique, associated with the Centre National de la Recherche Scientifique, the Universite Blaise Pascal. and the Observatoire de Physique du Globe de Clermont-Ferrand, France (host country). We wish to express our gratitude to the sponsors that made this conference possible. In addition to tinancial support from NATO/CCMS, the conference received contributions from Centre National de Recherche Scientitique, Observatoire de Physique du Globe de Clermont-Ferrand, Universite Blaise Pascal, Electricite de France, lnstitut Francais du Pe- trole, Conscil Regional d'Auvergne, Conseil General du Puy de DC1I11e, Mairie de Clermont- Ferrand, SATCAR Semaine des arts techniques et culture de l'automobile et de la route.