I never visited Alberta province. But there is so much oil/gas business and companies I was thinking that it may create some pollution. Oil refineries/ chemical plants/truck transportation/digging the land (removing snow/stones/sand)/ processing of oil sand/ Sour gas (H2S) may affect the people and the cities in long term.

You can search more details on net. here are few

http://web2.uwindsor.ca/flipside/vol3/jan00/00ja24a.htm
http://www.yaleinsider.org/article.jsp?id=12

Pollution has often been observed to suddenly stop in its tracks on reaching a geopolitical boundary, and wonder in which direction to travel next.

Oh no, sorry, I'm thinking of something else

I suppose that would explain why Calgary was considered the world's cleanest city in 2002?



"A new survey by William M. Mercer has identified that Canada and the US
have the cleanest two cities in the world. Calgary scores highest with an
environmental rating of 166, followed by Honolulu, which scores 161.5. The
Finnish capital Helsinki and Katsuyama in Japan share joint third place with a
score of 158. Two other North American cities, Ottawa and Minneapolis,
share joint fifth place in the list with a rating of 154.
Scores are based on the level of air pollution and the efficiency of waste
disposal and sewage systems. Cities are ranked against New York as the
base city, which scores 100. The analysis is part of a world-wide quality of life survey covering 215 cities. "

http://www.expat.or.id/info/qualityofliving.html

Calgary might be an 'oil town' but that doesnt mean we actually do the drilling here - we keep all the grubby stuff elsewhere! After all you wouldnt expect the people at the top of these companies to live somewhere that grubby would you?

As you mention, refineries, drilling, digging, trucking, processing all do create pollution - just not in Calgary yet. Try Edmonton/Sherwood Park for the refineries (among others)

Mrs G