Air pollution remains a major environmental issue despite many years of study and much legislative control. In rec~nt times, pollution on a global scale has become of particular concern. The gradually changing con­ centration of trace gases in the global troposphere due to man's activity is becomming a matter of serious concern. No scientist would dare to pre­ dict in detail the consequences of this gradual change due to its immense complexity involving social and economic factors and near countless chemical and phjsical cycles in our biosphere. In this chain of processes, the transport of pollution is an important factor, but only a factor. Therefore, I would like to emphasize that the mOdelling of atmospheric transport is becoming more and more an activity which fits into larger frameworks and can no longer be exercised as a single step, which bridges the gap between emissions and policy measures. This is also reflected in the topics and papers which were presented at this conference. The topics were: - emission invetories for and source treatment in air pollution dispersion models; - modelling of accidental releases; - regional and global scale dispersion mOdelling; including boundary layer-free troposphere exchange processes and subgrid scale parameter­ isations; - model verification and policy implications; - new developments in dispersion modelling and theory. 56 papers were presented in these sections. While many posters were dis­ cussed in a special session.

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Emission Inventories for and Source Treatment in Air Pollution Dispersion Models.- The Use of Emission Data Bases in Air Pollution Dispersion Modelling.- Evaluation of Hourly Emission Data.- Progress Report on Source Attribution via Numerical Labelling.- Modelling of Accidental Releases.- Modelling Dispersion from Accidental Releases.- Modeling the Dispersion of Accidentally-Released Toxic Gases Heavier than Air.- A Model for Accidental Releases in Complex Terrain.- Surface Pattern Comparability of Wind-Tunnel Simulations of the Thorney Island Dense Gas Dispersion Trials.- Dispersion of Dense Gas Releases in a Wind Tunnel.- A Lagrangian Model for the Real Time Simulation of Atmospheric Transport and Dispersion of Accidently Released Materials.- Influence of Non-Uniform Mixing Heights on Dispersion Simulations Following the Chernobyl Accident.- MLAM Assessment of Radionuclide Air Concentration and Deposition for the Chernobyl Reactor Accident.- Regional and Global Scale Dispersion Modelling Boundary Layer-Free Troposphere Exchange Processes and Subgrid-Scale Parameterisations.- Examining the Global Impact of Local/Regional Air Pollution: The Role of Global Chemical Transport Models.- Cumulus Cloud Vertical Transport Studies with the Moguntia Model.- Intercomparison of Long-Range Trajectory Models Applied to Arctic Haze.- Nitrogen Budget for Eastern Canada.- Transfer of Sulphur between Continents via the Mid-Latitude Free Troposphere.- Removal of Pollutants in Different Types of Precipitation.- Measurements and Models of Wet Deposition to Irregular Topography.- Description of Vertical Dispersion under Influence of Roughness Elements.- Acidity Production in a Mesoscale Model with Semi-Spectral Microphysics.- Modelisation of the Three-Dimensional Wind Field above the Alpine Region.- A Complex and a Simple Multi-Layer Chemical Cloud Model to Predict Scavenging and Wet Deposition.- Modeling of Wet Scavenging and Subgrid-Scale Vertical Transport by Clouds in a Tropospheric Chemical Model.- Model Verification and Policy Implications.- What is Required of Dispersion Models and do They Meet the Requirements?.- A North American Field Study to Evaluate Eulerian Models.- Comparison of Modelled and Measured Tracer Gas Concentrations during the across North America Tracer Experiment (ANATEX).- Results from a Comprehensive Acid Deposition Model: Predictions of Regional Ozone Concentrations.- Simulation of an Acid Deposition Episode over Europe with the TADAP/ADOM Eulerian Regional Model.- Studying the Sulphur and Nitrogen Pollution over Europe.- Power Plant Plume Dispersion Study in a Coastal Site with Complex Terrain.- A Case Study of Air Pollution in a Swiss Valley with a Multi Box Model.- Field Validation of Dispersion Models for Dense-Gas Releases.- Using the Øresund Experimental Data to Evaluate the ARAC Emergency Response Models.- An Examination of the Performance of Models for Dispersion in the Convective Boundary Layer.- New Developments in Dispersion Modelling and Theory.- New Developments in Dispersion Parameterization and Modeling.- Stochastic Modeling of Dispersion in the Convective Boundary Layer.- Fractal Concepts and the Analysis of Atmospheric Inhomogeneities.- Short Range Diffusion in Convective Light-Wind Conditions.- Adsorption-Kinetic Non-Linear Wash-Out Model of Sulphur and Nitrogen Compounds from the Atmosphere.- MSC-E EMEP New Models of the Long-Range Air Pollutant Transport.- Long Range Transport: Evaluation of a Particle-Incell Model Using Sources in the US and USSR.- Airflow and Dispersion over Complex Terrain.- Mesoscale Episode Modelling: Preparation of Input Data and Design of Realization.- IFDM-Superfast.- Experimental Measurements of Concentration Fluctuations.- Calculation of NO2 Concentrations in a Power Plant Plume Using a Classification of NO Oxidation Rates Based on Atmospheric Conditions.- Posters.- Deposition of Atmospheric Trace Metals to North Sea and Baltic Sea.- Calibration Field Work on Cooling Towers' Modelling.- Feedback of Environmental Survey Data for the Optimisation of the Input Parameters of Assessment Models during an Emergency.- Simulation of Effluent Dispersion in the Rhone River Valley Area the Code Hermes.- A Sulphur Hexafluoride Tracer Dispersion Study at the Sellafield Reprocessing Plant.- Dispersion of Aerial Agricultural Sprays: Model and Validation.- Comparison of Gaussian and Lagrangian Atmospheric Dispersion Models with Respect to Their Applicability for the Assessment of Short-Range Consequences of Accidental Releases.