1. Institute for Atmospheric and Climate Science, ETH Zurich, CH-8092Zurich, Switzerland
2. Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
3. Institute of Medical Virology, University of Zurich, CH-8057Zurich, Switzerland
4. Laboratory of Atmospheric Processes and Their Impacts, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
5. Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas, GR-26504Patras, Greece