The [Olympic] emission restrictions had an unmistakable impact. During the two months when restrictions were in place, the levels of nitrogen dioxide (NO2) -- a noxious gas resulting from fossil fuel combustion (primarily in cars, trucks, and power plants) -- plunged nearly 50 percent. Likewise, levels of carbon monoxide (CO) fell about 20 percent.The following images show comparative NO2 levels around China during August, 2005-2007 (left) and August, 2008 (right). Note the disappearance of the color red over Beijing in the image on the right.
Much of the air quality discussion on this blog and elsewhere has been about particulate pollution, not NO2 or CO, so it's nice to see the expanded analysis.
Monitoring of air pollution by satellite is just awesome. Last November, I heard a fascinating presentation by Argonne National Lab's Dr. David Streets on recent developments in satellite monitoring. It is getting so exact, he said, that, "we are exploring the potential of monitoring the change of power plant emissions in China from space." He then showed an example of pinpointing the opening of new power plants in Inner Mongolia through satellite observation:
Note pixel size of ~12km. Incredible.
Related post: final day of temporary air quality measures