Beijing did a lot to improve the air quality leading up to the Beijing Olympics, with mixed results. The days before the opening ceremony were pretty bad, but a burst of rain cleared the air and pollution became less of a talking point.

Almost straight after the closing ceremony the hazy skies returned. A few days later there was heavy rain and the last two days Beijing has had glorious weather - clear skies. warm weather and not too much humidity.

I turned to Wikipedia to find out more on cloud seeding and they have a good entry on the topic, with quite a few references to China. I was particularly interested in whether it has any environmental effects, but the article states:

The toxicity of silver and silver compounds (from silver iodide) was shown to be of low order in some studies. These findings likely result from the minute amounts of silver generated by cloud seeding, which are 100 times less than industry emissions into the atmosphere in many parts of the world, or individual exposure from tooth fillings.

I am sure there must be a certain financial cost to cloud seeding, but I wonder if authorities in China will start to think cloud seeding is a good, long term way to keep Beijing’s skies relatively pollution free.