1. Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Quebec, Canada;
2. Air Health Science Division, Health Canada, Ottawa, Ontario, Canada;
3. School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada;
4. Department of Environmental Health Sciences, Yale School of Public Health, New Haven, Connecticut; and
5. Department of Civil and Mineral Engineering,
6. Department of Chemical Engineering and Applied Chemistry, and
7. Population Studies Division, Health Canada, Ottawa, Ontario, Canada