|The project aspires to understand and quantify the relative contribution of bioorganic components to the observed aerosol concentration levels in Mediterranean environment and to develop and validate a 3-D aerosol/photochemical/radiative modelling tool, enabling the assessment of the bioorganic contribution to aerosols and the radiative forcing by these on climate. These goals will be satisfied through the implementation of laboratory experiments, field measurements. The proposed project focuses on two representative Mediterranean regions with elevated bioorganic emissions and sufficient degree of diversity (Marseilles, Athens). However, the overall methodology will be applicable to any other European region. The project results (3-D aerosol modelling tool, inventories and development methodology, chemical mechanisms of secondary organic aerosol (SOA) formation and assessment of radiative forcing by SOA on regional scale) should enable the formulation of cost-effective aerosol control, mitigation strategies and measures thus, avoiding wasted expenditures and delays in reaching attainment of targets.