The Pickering plant is only about 3 km from the city of Toronto's border. While it was selected in the 60s as a relatively remote site, it's now a heavily urbanized area considered part of Greater Toronto.
I was wondering about this today. How granular are the 'zones' used for these alerts? Is it just by political boundary? For something like Pickering, it would be useful to have a more geographical zone -- including parts of the US. Could the alert be sent out and limited to cell towers within a selected zone? Is the current system using tower location?
They have the ability to geotarget them, but fail at it regularly.
From what I understood from spectrum auctions, Gatineau Quebec is a part of the Ottawa area, so they're probably a part of Ontario side when it comes to cell system back-end.