"I can't recall too many "environmentalists" objecting to China's pollution index. Have you?"
I wouldn't know, because they are probably illegal in China. As for leftists here, I have heard complaints. But what can they do?
Fortunately, they can do to environmentalists and labor union types in China (like in the photos of the Tibetans they executed) things we couldn't even consider here....
Seems to me they could do some of the same things they've done when critical of American environmental policies and practices -- organize protests and demonstrations in front of the Chinese embassies and consulates, demand that China sign on to Kyoto, call for boycotts of Chinese goods, pressure Congress to impose restrictions on trade, step into the MSM spotlight.
Maybe I'm just naive, but I can't see what would stop them -- unless they're just reluctant to put pressure on a communist country.