PMCOST addresses the key challenge of particulate matter (PM) air pollution in Poland which is one of the major threats to human health across the country and Europe in general. To date air pollution modelling in Poland has not received the investment needed to fully grasp these challenges. PMCOST brings together the leading Polish researchers on air pollution together with world leading experts from UK and Norway to address this challenge. This twinning of researchers, matches complementary areas of expertise and will enable Poland to be more effective in supporting Polish policy makers and other stakeholder in developing plans for better air quality in Poland. At the same time, it will provide the technical underpinning for Poland to become an international leader in assessment of transboundary air pollution, especially in relation to the UNECE Geneva Convention on Long-range transboundary air pollution, and in support of the European Air Quality Directive. The project will develop a capability in Poland for state of the art atmospheric chemistry transport modelling (ACTM). This will permit a detailed national assessment of the complex chemical composition of PM, the main contributing emissions sources and the most effective strategies to protect human health through targeted emissions abatement. To achieve this goal PMCOST will focus on three core Twinning Activities: Training of Polish staff through two-way exchange with the expert partners; Improving the output of high quality peer reviewed publications; Developing the interface between scientists and stakeholders and policy makers through thematic workshops. The key aspects of the Training Programme are represented by three of the five work packages focused on preparation of high quality emissions data for use in ACTMs, operational air pollution modelling of PM and assessing the human health benefits of different emission abatement options.