Cleaner Skies during the COVID-19 Lockdown (Christiane Voigt, Jos Lelieveld, Hans Schlager, Johannes Schneider, Joachim Curtius, Ralf Meerkoetter, Daniel Sauer, Luca Bugliaro, Birger Bohn, John N. Crowley, Thilo Erbertseder, Silke Gross, Valerian Hahn, Qiang Li, Mariano Mertens, Mira Pöhlker, Andrea Pozzer, Ulrich Schumann, Laura Tomsche, Jonathan Williams, Andreas Zahn, Meinrat O. Andreae, Stephan Borrmann, Tiziana Braeuer, Raphael Doerich, Andreas Doernbrack, Achim Edtbauer, Lisa Ernle, Horst Fischer, Andreas Giez, Manuel Granzin, Volker Grewe, Hartwig Harder, Martin Heinritzi, Bruna Amorim Holanda, Patrick Joeckel, Katharina Kaiser, Ovid O. Krueger, Johannes Lucke, Andreas Marsing, Anna Martin, Sigrun Matthes, Christopher Poehlker, Ulrich Poeschl, Simon F. Reifenberg, Akima Ringsdorf, Monika Scheibe, Ivan Tadic, Marcel Zauner-Wieczorek, Rolf Henke, Markus Rapp)