NARRAGANSETT, R.I. – July 14, 2008 – The outlook for air quality in Beijing during the Olympics is borderline, and there's little that the Chinese government can do to improve it. That's the conclusion drawn by a University of Rhode Island atmospheric chemist who analyzed pollution data collected regularly for the last five years by Chinese scientists.
"There is both a local component and a regional component to the pollutants that cause unhealthy air in Beijing, and the severity of their effects are driven by weather fronts and winds," said Kenneth Rahn, a retired URI professor who travels to China several times a year to help scientists at Tsinghua University interpret their data. "Since it's controlled by the weather, it will be a matter of luck whether the bad air periods correspond with days of outdoor Olympic events."
Locally generated pollutants in Beijing consist primarily of organic matter from transportation, factories and cooking, while regional sources of pollution include ammonium sulfates and ammonium nitrates from coal-burning power plants, industry and transportation sources, which are easily transported long distances in the atmosphere, according to Rahn.
"The air pollution pattern in Beijing is unusual, with high and low concentrations that can differ by a factor of 50 to 100," Rahn said. "When the winds shift to the north and bring in clear air from Mongolia, the air can be relatively clean, though that's not the norm during the summer. But when winds are from the south, where there is a large population and lots of industrial activity, the air can be particularly hazardous."
When air quality in Beijing is at its worst, Rahn says, most of the pollutants come from distant sources, making it virtually impossible for local efforts to lead to the kind of improvements that the government would like.
"It's one thing to take steps to try to clean up a big city, but unless they also clean up the surrounding provinces, it's going to have a minor effect," said Rahn. "They've tried to relocate some of the polluting industries over time, and Beijing has gotten a little cleaner each year because of it, but the background pollutants still blow in just the same."
The government's plan to reduce pollution during the Olympics focuses on cutting automobile use in half while also temporarily shutting down factories and other large polluters. Rahn said that it is an expensive plan, since the government must reimburse the factories for their economic losses, and the plan will remain in place through the conclusion of the Paralympic Games in late September.
A test run of the transportation component of the pollution reduction plan conducted last summer resulted in undetectable air quality improvements.
"I sympathize with them. They're doing all the right things, but unfortunately the right things may not be good enough," Rahn said. "There will surely be some good days and some bad days. But the meteorological uncertainties mean that you can't predict how bad it will be more than two or three days ahead, and that may not be enough time for them to reschedule the marathon or the long-distance bike races.
"My advice to them at this point is to keep up the good work and then pray to the Mongolian Weather Gods to send cold fronts. That's their best hope for clean air."