In 1969 the North Atlantic Treaty Organization (NATO) established the Committee on Challenges of Modern Society (CCMS). The subject of air pollution was from the start one of the priority problems under study within the framework of various pilot studies undertaken by this committee. The organization of the periodic conference, named NATO/CCMS International Technical Meeting (ITM) on Air Pollution Modelling and Its Application, has become one of the main activities. The present 29th edition confirms the continuous evolution, the interest, the high level confidence of the scientific community and several other supports gained for this Conference.