Probably the most important one is just to say the same thing for air pollution that the bill now says for water pollution, that significant air pollution that crosses national or provincial borders should be subject to federal environmental assessment. There are other things that could be added on to that.
I would do that obviously in a way that respects co-operative federalism. If provinces are adequately addressing the matter, then the federal government could step back, as it does with most environmental laws, but it needs to have that power in the act sooner rather than later.