1. Environmental
Geosciences, University of Basel, Bernoullistrasse 30, 4056 Basel, Switzerland
2. Air
Pollution Department, Environmental Sciences Division, National Research Centre, 33 El-Bohouth Street, Dokki, Giza 12622, Egypt
3. Institute
of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland