You just have to look at the graph, with its large numbers in the West, half in BC, and none in the Eastern Provinces, to work out where it is coming from. The two Provinces most affected also happen to be the ones whose largest cities have sky-high housing prices because of massive foreign ownership, often by foreign "students" with no obvious source of income. 

I think the "clandestine labs" described by the G&M are hiding in plain sight.