The NY Times reports that a new PNAS paper finds that an unintended consequence of Chinese production of goods is to raise urban air pollution in the United States. Given that a large share of China's production go to the United States, an economist might ask the following question; "How much higher would U.S pollution levels be if the manufacturing activity that generates the goods that U.S consumers consume all took place in the United States?" We know that air pollution and water pollution drifts across boundaries. I do agree that that it is interesting to quantify these effects. The authors appear to use a complicated spatial model for teasing out the origin and destination of various emissions. The estimated effects appear to be quantitatively small (i.e 2% higher). As China's coastal eastern cities deindustrialize, this U.S externality effect will further shrink.
So, from a day to day quality of life green cities point of view; the United States should thank China. U.S cities are greener because of our deindustrialization.