1. Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
2. Aerodyne Research Inc., Billerica, Massachusetts 01821, United States
3. Department of Chemistry, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan 48109, United States
4. Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan 48109, United States
5. Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02459, United States
6. Department of Atmospheric Sciences, The Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149, United States
7. Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, United States