edit /update 2 August 09
So, here comes the big obfuscation of the truth. The official API figures as from our BEPB who proudly can say there were soooo many blue sky days in Beijing.

Some naïve foreigners (CNN lazy journalists included) swallow it all, look in amazement at the blue sky. Funny, haven’t seen actually much sky and neither the buildings around me. The air has been very bad for many days as confirmed by the U.S. Twitter data. Those average AQI 180 roughly (“unhealthy”) but with peaks of over 400 and one of 500 (HAZARDOUS). Of course BEPB is not any time soon going to measure PM2.5. Too embarrassing.
According to BEPB, up to now we had in Beijing 172 days of “blue sky” (API lower or equal to 100). The goal for 2009 is 260 days (71%). Looks like they will have their gold medal of misleading this year.
Obviously the BEPB loses all credibility. So, for some time I will stop recording their data as it is a waste of time.

Yes, you dummies, the Twitter stuff is in a bad area, called CBD. Oops, see the attached official ENLARGED CBD area that is still a taxi ride far from the embassy. And Dongsi is overall worse.
Not to wonder parents have to make a tough choice – raise their kids in this hazardous environment or head back home where they might not have a job.
Sounds like Chinese migrants working in hazardous factories where they end up with irreversible lung damage. According to China Daily, nearly 640,000 people suffer from pneumoconiosis in China today.

Then to say our “compatriots” in Hongkong worry about their “bad” air. Probably much better than here. They now also push to measure PM2.5.