Atmospheric chemist Kenneth Rahn regularly travels to China to consult with scientists there about the country's air pollution problem. Rahn took your questions about pollution in Beijing during the run-up to the Olympic Games.
I had a chance to see and breathe the Beijing pollution first hand three months ago. But I have not been able to find the chemical description of the pollution and how it compares with U.S. cities. Would you provide that information?
Kenneth Rahn responds:
It's a few times higher than most U.S. cities, and unusually enriched in particulate matter from soil dust and coal combustion.
Beijing has an arid climate similar to much of the American West. It gets half the precipitation of the American East, and during the winter as little as one-quarter inch a month. That allows a great deal of soil dust to be generated, and lets all kinds of pollutants stay in the air after they are released. This is one of the main reasons that external sources are so important to Beijing.