Re-evaluating the Contribution of Sulfuric Acid in Atmospheric Nanoparticle Growth. VILLE VAKKARI, Petri Tiitta, Kerneels Jaars, Philip Croteau, Johan Paul Beukes, Miroslav Josipovic, Veli-Matti Kerminen, Markku Kulmala, Andrew D. Venter, Pieter G. van Zyl, Douglas Worsnop, Lauri Laakso, Finnish Meteorological Institute, Helsinki, Finland