China is the second largest consumer of energy next to the USA with coal as its primary fuel. Large amount of carbon emissions and sulfur dioxide (major ingredients of acid rain) from its power power plants plus the growing number of automobiles in the country would lead to what's going on in this image.

A visible pool of air pollution from China is being carried by the Westerlies toward downwind countries like South Korea, Japan and Taiwan. Trans-boundary pollution like this one happens regularly in many places around the globe.

This image is taken from, the SeaWiFS Mission, which is part of NASA's Earth Science Enterprise, designed to look at our planet from space to better understand it as a system in both behavior and evolution.