Toronto, Ontario is 400km from Ohio, and gets smog from Ohio's coal plants all the time. The studies suggest about half of Toronto's air pollution is due to U.S. power plants.
I have no idea what the reality is of smog in Europe, but your off-hand dismissal of this based on the perceived distance between the source and recipient of the pollution is entirely wrong.
I have no idea what the reality is of smog in Europe, but your off-hand dismissal of this based on the perceived distance between the source and recipient of the pollution is entirely wrong.