There has been some work done by Environment Canada, supported by Health Canada, looking at synoptic situations.
The important thing to keep in mind is that it's not just temperature driven, that there's complex meteorology involved.
On May 17th, 2007. See this statement in context.
May 17th, 2007 / 12:45 p.m.
Acting Manager, Air Health Effects Division, Healthy Environments and Consumer Safety Branch, Department of Health
There has been some work done by Environment Canada, supported by Health Canada, looking at synoptic situations.
The important thing to keep in mind is that it's not just temperature driven, that there's complex meteorology involved.
See context to find out what was said next.