1. Department of Chemistry York University Toronto ON Canada
2. Chemical Sciences Laboratory NOAA Boulder CO USA
3. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Boulder CO USA
4. Department of Chemistry University of Colorado Boulder Boulder CO USA
5. School of Earth and Atmospheric Sciences Georgia Institute of Technology Atlanta GA USA
6. Department of Chemistry University of Toronto Toronto ON Canada
7. Now at Picarro Inc. Santa Clara CA USA
8. Air Quality Research Center University of California, Davis Davis CA USA
9. Office of Air Quality Planning and Standards U.S. EPA, Research Triangle Park Durham NC USA