1. Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
2. Department of Sociology, University of New Brunswick, Fredericton, New Brunswick, Canada
3. College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, USA
4. Air Quality Research Division, Environment Canada, Downsview, Ontario, Canada
5. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
6. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
7. Institute of Health: Science, Technology and Policy, Carleton University, Ottawa, Ontario, Canada
8. School of Public Health, University of California, Berkeley, Berkeley, California, USA
9. Department of Medicine, McGill University, Montreal, Quebec, Canada
10. Division of Clinical Epidemiology, Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
11. Department of Economics, Brigham Young University, Provo, Utah, USA
12. School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada
13. Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
14. Atmospheric Science and Technology Directorate, Environment Canada, Dorval, Quebec, Canada