Earlier today I happened to read an article on Channel News Asia about a documentary on air pollution in China. None of the links now seem to work at Channel News Asia, but the BBC has a similar article. The documentary below is interesting and depressing, and one can clearly see clear why the Chinese government would prefer not to have the documentary circulating. The documentary is not without its own biases and hypocrisy--e.g., the journalist burns much fuel flying to various countries to interview people (and fly in a helicopter over LA) while urging everyone else to take public transportation and use less coal and oil--but it was worth watching, in part because it was information from Chinese within China about a serious problem inside China.
I also know what it's like to live for years with potentially unhealthy kerosene heating, as I did in Tokushima, Japan.
The documentary is titled Under the Dome and is well subtitled in English.