In 1969 the North Atlantic Treaty Organization established the Committee on the Challenges of Modern Society. Air Pollution was from the start one of the pri9rity problems under study within the framework of the pilot studies undertaken by this Committee. The organization of a yearly symposium dealing with air pollution modeling and its application is one of the main activities within the pilot study in relation to air pollution. After being organized for five years by the United States and for five years by the Federal Republic of Germany, Belgium, represented by the Prime Minister's Office for Science Policy Programming, became responsible in 1980 for the organization of this symposium. This volume contains the papers presented at the 13th Inter national Technical Meeting on Air Pollution Modeling and its Appli cation held at lIe des Embiez, France, from 14th to 17th September 1982. This meeting was jointly organized by the Prime Minister's Office for Science Policy Programming, Belgium, and the Ministere de l'Environnement, France. The conference was attended by 120 participants and 45 papers have been presented. The closing ses sion of the 13th I. T. M. has been attended by Mr. Alain Bombard, French Minister of the Environment. The members of the selection committee of the 13th I. T. M. were A. Berger (Chairman, Belgium), W. K1ug (Federal Republic of Germany), K. Demerjian (United States of America), L. Santomauro (Italy), M. L. Williams (United Kingdom), H. Van Dop (The Netherlands), H. E. Turner (Canada), C.