"Homegrown air pollution is bad enough, but for years scientists have tracked pollution rising out of Asia, crossing the Pacific Ocean, and descending over the western United States. A research team found that the Asian contribution over the southwestern United States could amount to 15 parts per billion of ozone (orange-red on three consecutive days in panels, left to right). That could become even more troublesome, the authors note, if Asian imports increase as expected in the coming decades."
So in essence, sending manufacturing to China to avoid the Clean Air Act costs doesn't always lower our monetary costs nor does lower our environmental costs (not if our air is still polluted). Geography is all about understanding the whole system, and the atmosphere does not recognize any international borders. The Earth is our system.