Lowest pollution Canadian province/s? (air pollution, health, interior)

[movintime]

Is it eastern provinces such as Maritime or NL, or the western ones as in BC, AB, etc. It may even be interior Canada but I assume coastal is clearer weather/air. But the air pollution drifting more daily from China, may oust the west coast of US & Canada as far as health/air quality goes.

I'm having a debate w/ a friend of mine, & as as per usual we don't agree on these issues & what factors directly contribute. So, I bring this to you "experts", haha, to help mitigate the argument.