I think the scope is potentially quite broad, given that most of the air pollutants of concern, both the smog precursors and the hazardous air pollutants, are already on the list of toxic substances, so the potential scope of federal regulatory actions is already quite wide.
I would think a potential model for that is the one that exists, for example, under the U.S. Clean Air Act with the notion of a non-attainment area. The implication, of course, is you have to have some sort of national ambient air quality standard against which you could then say that this location in Fort McMurray or wherever fails to achieve those standards, and therefore, further interventions are required.
I think it's entirely feasible, and we have precedents for doing that, either as toxic substances, but also, as was suggested, we could do interprovincial air pollution as well. I think it's quite doable. The pieces we don't have are provisions around air quality standards per se, but that's not infeasible. There could be guidelines that would then be triggers for regulatory action in relation to the toxic substances that were implicated in a failure to achieve the ambient air quality standards.