1. Gage Occupational and Environmental Health Unit, St. Michael’s Hospital, Toronto, Ontario, Canada
2. Department of Public Health Sciences,
3. Department of Medicine, and
4. Department of Chemical Engineering, University of Toronto, Toronto, Ontario, Canada
5. Air Quality Research Branch, Meteorological Service of Canada, Environment Canada, Toronto, Ontario, Canada
6. Mount Sinai School of Medicine, New York, New York, USA
7. Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA