1. Department of Chemistry and Centre for Atmospheric Chemistry, York University, 4700 Keele Street, North York, Ontario M3J 1P3, Canada
2. Desert Research Institute, P.O. Box 60220, Reno, Nevada 89506
3. Science Division, Environment Canada, 700-1200 West 73rd Avenue, Vancouver, British Columbia V6P 6H9, Canada
4. Pollution Management Division, Environmental Technology Centre, Ottawa, Ontario K1A OH3, Canada
5. Institute for Chemical Process and Environmental Technology, National Research Council, Ottawa, Ontario K1A 0R6, Canada