TreeHugger has a summary of what cyclists can do to protect their lungs from car pollution. If you’re worried about cycling in cities because of pollution, just remember that the health (and environmental) pros of cycling outweigh the cons.
By cycling instead of driving or taking public transport, you are doing your part to keep the air clean. The problem is that you have to cycle through all the pollution created by people who aren’t making any effort.
The Spacing Wire has information on what Canadians can do to get the federal government to support cycling.