"Air quality is strongly dependent on weather and is therefore sensitive to climate variability and climate change. On the other hand, air pollution affects the atmospheric composition which in turn affects the earth's radiative budget and the earth's climate. Hence the climate and the air quality are intimately interactive parts of the earth's system and the feedbacks between them can act to amplify or dampen climate sensitivity. These complex interactions are not well understood but are critical to the behavior of the system as a whole and should be taken into consideration into the design of effective policies.The REQUA project aims at strengthening the research partnership through staff exchanges and networking activities between research groups in Europe, USA and China working in the field of regional climate-air quality interactions. The general scientific goal is to advance the current understanding of interactions between different components of the earth system. The project will be based on two regional chemistry-climate models, one developed in USA and one in Europe: (i) WRF-CMAQ, a well established online modeling system, and (ii) RegCM-CHEM, an integrated regional climate model with a reduced chemical scheme.The consortium consists of a team of 8 partners, namely 4 EU research teams (from Greece, Italy, Bulgaria and UK) and 4 from third countries (USA and China). All participants have extensive experience in different aspects of air quality/climate interactions, combining different aspects expressed by different skills, tools and equipment. Most of the partners have already developed some collaboration, however the consortium is novel.The planned activities include joint research work, workshops, training courses and seminars. All activities are designed to exploit complementary expertise of the participants and to create synergies between them. They are also planned to create additional benefits for the participants in terms of transfer of knowledge."