This volume is concerned with the physics and the application of air pollution modeling on scales up to about 50 km. Its eight chapters, comprising the diverse points of view of seven authors, remain substantially in their original, lecture-note form. The result is not a smoothly flowing monograph but instead a richly textured, lively collection of the seasoned thoughts and perspectives of experienced researchers and practitioners.

This publication of the AMS contains all the lectures that were presented at the AMS Workshop on Meteorology and Environmental Assessment held in Boston, MA on September 29-October 3, 1975. Topics include: The dispersion of materials in the atmospheric boundary layer, atmospheric dispersion models for environmental pollution applications, plume rise predictions, turbulent diffusion and pollutant transport in shoreline environments, urban diffusion problems, atmospheric transformations of pollutants, observational systems and techniques in air pollution meteorology, and federal government requirements for environmental impact assessment.

This volume covers the latest scientific developments in the real world applications of pollution modeling. Topics covered include: the role of atmospheric models in air pollution policy and abatement strategies; integrated regional modelling; global and long-range transport; aerosols as atmospheric contaminants; model assessment and verification; and application of new concepts in different regions of the world.

Finishing this book is giving me a mixture of relief, satisfaction and frus tration. Relief, for the completion of a project that has taken too many of my evenings and weekends and that, in the last several months, has become almost an obsession. Satisfaction, for the optimistic feeling that this book, in spite of its many shortcomings and imbalances, will be of some help to the air pollution scientific community. Frustration, for the impossibility of incorporating newly available material that would require another major review of several key chap ters - an effort that is currently beyond my energies but not beyond my desires. The first canovaccio of this book came out in 1980 when I was invited by Computational Mechanics in the United Kingdom to give my first Air Pollution Modeling course. The course material, in the form of transparencies, expanded, year after year, thus providing a growing working basis. In 1985, the ECC Joint Research Center in Ispra, Italy, asked me to prepare a critical survey of mathe matical models of atmospheric pollution, transport and deposition. This support gave me the opportunity to prepare a sort of "first draft" of the book, which I expanded in the following years.

Atmospheric chemistry is one of the fastest growing fields in the earth sciences. Until now, however, there has been no book designed to help students capture the essence of the subject in a brief course of study. Daniel Jacob, a leading researcher and teacher in the field, addresses that problem by presenting the first textbook on atmospheric chemistry for a one-semester course. Based on the approach he developed in his class at Harvard, Jacob introduces students in clear and concise chapters to the fundamentals as well as the latest ideas and findings in the field. Jacob's aim is to show students how to use basic principles of physics and chemistry to describe a complex system such as the atmosphere. He also seeks to give students an overview of the current state of research and the work that led to this point. Jacob begins with atmospheric structure, design of simple models, atmospheric transport, and the continuity equation, and continues with geochemical cycles, the greenhouse effect, aerosols, stratospheric ozone, the oxidizing power of the atmosphere, smog, and acid rain. Each chapter concludes with a problem set based on recent scientific literature. This is a novel approach to problem-set writing, and one that successfully introduces students to the prevailing issues. This is a major contribution to a growing area of study and will be welcomed enthusiastically by students and teachers alike.

Proceedings of the Millennium NATO/CCMS International Technical Meeting on Air Pollution Modeling and its Application, held May 15-19 in Boulder, Colorado. This volume is the latest in a series of proceedings dating back to 1971. The book addresses the problem of air pollution and reports the latest findings and developments in air pollution modeling, from a truly international list of contributors.

The 20th International Technical Meeting on Air Pollution Modelling and Its Application was held in Valencia, Spain, during late 1993. At this conference, a new record of abstracts was submitted, a new record of scientists participated, and a new record of countries was represented. This clearly indicates society's continuous and growing interest in, as well as importance of, the complexities associated with the modelling of air pollution. The conference addressed the following main subjects: integrated regional modelling, global and long-range transport, new modelling developments, accidental releases, and model assess ment and verification. In addition, two project-oriented workshops were organized as part of the conference. The many contributing authors and scientists taking active part in the discussions following the papers, have made this proceeding a record of the current status in the field of air pollu tion modelling. We want to express our gratitude to their efforts. We also wish to extend our gratitude to the sponsors that made this conference possible. In addition to financial support from NATOjCCMS the conference received contributions from CEAM, the European Asso ciation for the Science of Air Pollution, Danish Center for Air Research, and Ris0 National Laboratory. A special grant was given by NATOjCCMS to facilitate attendance of scientists from Central and Eastern Europe. We also wish to express our gratitude to Rosa Salvador and Pilar Zamora of CEAM, who laboriously organized the conference pre-proceedings, and to Anne N0rregaard and Ulla Riis Christiansen of Ris0 National Laboratory, who seved as conference secretariat.

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 a yearly conference dealing with air pollution modeling and its application has become one of the main activities within the pilot study relating to air pollution. The international conference was organized for the first five years by the United States and for the second five years by the Federal Republic of Germany. Belgium, represented by the Prime Minister's Office for Science policy, became responsible in 1980 for organizing the third five years of the annual conference. This volume contains the papers presented at the 15th NATO/CCMS International Technical Meeting (ITM) on Air Pollution Modeling and Its Application, held in St. Louis, Missouri, from the 15th to 19th April 1985. This ITM was jointly organized by the Prime Minister's Office for Science Policy, Belgium (Pilot Country); by the Environmental Protection Agency, Atmospheric Sciences Research Laboratory, United States (Host Country); and by Washington University, Mechanical Engineering Department (Host Organization).

In 1949, when the North Atlantic Treaty was ratified, one of its articles explicitly noted '1hat member countries should contribute towards the further development of peaceful and friendly international relations." Specific problems related to the human environment were addressed by the Committee of Challenges of Modern Society (CCMS) of NATO, established in 1969. This provided a framework within which a series of International Technical Meetings (ITMs) on Air Pollution Modelling has been held. This volume documents the proceedings of the 18th meeting in this series. Science, like the arts and sports, provides an ideal vehicle for "developing peaceful and friendly international relations". National boundaries have never been barriers to the movement of air pollution, and fortunately this has also proved true of scientists studying the transport of air pollution. It is thus satisfying to record that since the mid-seventies it has been commonplace to find Eastern European scientists among attendees at the ITMs which have (in a very modest way) participated in a precursor to the process which has led to historical changes in Europe and which will undoubtedly lead to a tremendous increase in personal and intellectual exchange on a worldwide basis.

This is the first in a new series of publications arlslng out of the work of the Committee on Challenges of Modern Society of the North Atlantic Treaty Organization. The CCMS was established in 1969 with a mandate to examine practical ways of improving the exchange of experience among mem ber nations of the Alliance in the task of creating a better envir onment for their societies. It was charged with considering "spe cific problems of the human environment with the deliberate objec tive of stimulating action by member governments". It may come as a surprise to some that NATO - generally thought of as being an organization devoted solely to matters of defence - should concern itself with the environment at all. But this is to overlook Article 2 of the North Atlantic Treaty of 1949, which expressly provides that member count ries should contribute towards the furt her development of peaceful and friendly internat ional relations by promoting conditions of stability and well being. This concern is reflected in many non-military areas, in addition to the environmental one. I wish the present volume, which has been edited by the Bel gian Prime Minister's Office for Science Policy Programming, every success.