For example, in Montreal, about half of the air pollution is actually generated in the Mid-West US.
Yeah, and the other 1/2 comes from Ontario.
It sounds like you have what is called late response vs. early response exercise induced asthma (EIA). (Specifically a subcatagory called refractory period EIA.) It is significant since over the counter bronchodilators when used before excercise only helps the early response EIA.
No, it is only from the Toronto air and that is why my lungs are soooo happy to be living in the west.