Dispersion modelling has been an effective tool to assess the environmental impact of human activities on air quality already at the early planning stage. Environmental assessments during planning are required by the European Union directive 85/337/EEC. Only models can give detailed information on the distribution of pollutants with high spatial and temporal resolution, while they allow the decision-maker to devise a range of scenarios, in which the various processes determining the environmental impact can be easily simulated and changed.
Furthermore, the implementation of the European Union framework directive on air quality (2008/50/EC) and its daughter directives requires an extensive assessment of air quality in the EU member states. The required tools include air-quality models for assessing regional and urban air quality. There is a fundamental need for the European countries to build upon the experiences of each other according to the requirements in the framework directive, and to harmonise the development and use of models in several respects.
In June 1991, at a meeting at the Joint Research Centre of the European Commission, an initiative was launched on the sharing of information and possible harmonisation of new approaches to atmospheric dispersion modelling and model evaluation. This initiative has fostered a series of conferences that have been concerned with improvement of "modelling culture" in Europe.
The 16th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes in Varna, Bulgaria, will continue the efforts of the previous conferences. The conference is a forum where users and decision-makers can bring their requirements to the attention of scientists. It is also a natural forum for discussing environmental issues related to the European Union enlargement process.