SOA Formation from OFR Oxidation of Rural and Urban Ambient Air Suggests Widespread Importance of S/IVOC Precursors. BRETT PALM, Amber Ortega, Weiwei Hu, Douglas Day, Pedro Campuzano-Jost, William Brune, Lisa Kaser, Thomas Karl, Hansel Armin, James Hunter, Eben Cross, Jesse Kroll, Martin Graus, Carsten Warneke, Jessica Gilman, Joost de Gouw, Suzane de Sá, Lizabeth Alexander, Scot Martin, Roger Seco, Jeong-Hoo Park, Alex Guenther, Saewung Kim, Jose-Luis Jimenez, et al., CIRES, University of Colorado