1. Empa, Swiss Federal Laboratories for Materials Testing and Research; Air Pollution and Environmental Technology; Dubendorf; Switzerland
2. Centre for Atmosphere Watch and Services, Key Laboratory for Atmospheric Chemistry; Chinese Academy of Meteorological Sciences, China Meteorological Administration; Beijing; China
3. School of Chemistry; University of Bristol; Bristol; UK
4. Department of Geosciences; University of Oslo, Blindern; Oslo; Norway
5. School of Earth and Atmospheric Sciences; Georgia Institute of Technology; Atlanta; Georgia; USA
6. Institute of Chemical Sciences; University of Urbino; Urbino; Italy
7. Department of Earth, Atmospheric, and Planetary Sciences; Massachusetts Institute of Technology; Cambridge; Massachusetts; USA