M. Lazaridis_1,2, D. N. Asimakopoulos₆, M. Branis₈, I. Colbeck₃, I. Drossinos₄, C. Dye₁, 
K. Eleftheriadis₅, H. Flocas₆, C. Helmis₆, W. Hollander₉, Housiadas₅, J. Hovorka₈,
N. Kalogerakis₂, M. Petrakis₁₀, J. Smolik₇, F. Stordal₁, T. Svendby₁ and V. Zdimal₇

1. Norwegian Institute for Air Research (NILU), PO BOX 100, N 2007 Kjeller, Norway.

2. Technical University of Crete, Department of Environmental Engineering, 73100 Chania, Greece

3. Department of Biological Sciences, University of Essex, U. K.

4. Institute for Systems, Informatics and Safety (ISIS), JRC-Ispra, Italy.

5. N.C.S.R. Demokritos, 15310 Ag. Paraskeui, Attiki, Greece.

6. University of Athens, Department of Physics, Greece.

7. Institute of Chemical Process Fundamentals, ASCR, Prague, Czech Republic

8. Charles University, Faculty of Science, Prague, Czech Republic

9. Fraunhofer-Institut fur Toxikologie und Aerosolforschung (FhG/ITA), Hannover, Germany

10. Institute for Environmental Research & Sustainable Development National Observatory of Athens, Athens, Greece