I'm sure Ambassador Jacobson has a thought on this as well, but as I'm sure you know there is an existing Canada-U.S. Air Quality Agreement that needs to be strengthened and enforced. I don't know the exact status of it, but it is under negotiation.
The air quality is actually improving in southern Ontario. Part of that is due to the fact that there's less coal being burned in U.S. utilities in the Midwest. Part of that is because there's less coal being burned in Ontario, or no coal anymore, and also improvements in vehicle emissions and other sources as well.
But yes, there's more work to be done on that, for sure.