Choking on progress: soaring levels of pollution are a dangerous side effect of China's economic boom.

Economic growth tops 9 percent! Textile exports jump 500 percent! The steady stream of statistics trumpeting China's booming economy is often viewed by the rest of the world with a combination of amazement and envy.

But one statistic should cause alarm, both inside and outside China. Zhang Lijun, a top Chinese environmental official, warns that pollution levels in China could more than quadruple within 15 years if the country does not curb its energy consumption and automobile use.

China has reached a tipping point familiar to many developed countries, including the U.S., that have raced after economic development, only to look up suddenly and see the environmental carnage. The difference with China is that the potential problems are much bigger, have happened much faster, and could pose greater concerns for the entire world.

China is already the world's second-biggest producer of greenhouse-gas emissions and is expected to surpass the U.S. as the biggest. Roughly 70 percent of China's rivers and lakes are polluted, and one third of China is exposed to acid rain. A study found that 400,000 people die prematurely every year in China from diseases linked to air pollution.

FROM CHINA TO L.A.

On November 13, an explosion at a chemical plant in Jilin Province dumped 100 tons of toxic benzene compounds into the Songhua River. When the 50-mile slick reached Harbin, a city of 4 million, the water system was shut down and residents had to turn to bottled water. Two weeks later, Chinese officials declared the Songhua's water fit to drink--even as Russia prepared for the slick to cross the border and approach the town of Khabarovsk.

China's air pollution travels as well: On some days, almost 25 percent of the smoke, soot, and other pollutants clotting the skies above Los Angeles can be traced to China, according to the U.S. Environmental Protection Agency.

President Hu Jintao repeatedly mentions the environment in his speeches, and China's State Environmental Protection Administration, or SEPA, has become more aggressive in going after polluters.

But the practical and political obstacles are daunting. Car ownership has become part of the Chinese middle-class dream. Local officials often ignore emissions standards for polluting factories that pay local taxes: SEPA has closed factories, only to see them reopen weeks later.

For the Communist Party--which has based its legitimacy on delivering economic growth--the question is how to curb pollution without crippling the economy: Chinese leaders fear that a slowdown could lead to social instability.

TIGER LEAPING GORGE

Pollution, however, is already generating unrest. Residents of Dongzhou, a village in southern China, say that as many as 20 villagers were killed by security forces on December 6 while protesting plans for a power plant they fear will destroy their livelihood as fishermen. It was the deadliest use of force by Chinese authorities against ordinary citizens since the Tiananmen Square massacre in 1989.

There is also mounting tension in western China over a proposed hydroelectric dam at Tiger Leaping Gorge that environmentalists say would flood the gorge and displace 100,000 farmers and villagers.

"This is the political lens to watch China through today," New York Times Op-Ed columnist Thomas L. Friedman wrote in November. "How China's ruling Communist Party manages the environmental, social, economic, and political tensions converging on places like Tiger Leaping Gorge--not Tiananmen Square--will be the most important story determining China's near-term political stability."

There has been some progress. A new law requires that China produce 10 percent of its energy from renewable sources by 2020. Fuel-efficiency standards for new cars are already stricter than those in the U.S.

Ma Jun, an independent environmentalist based in Beijing, says China's status as the "workshop of the world" made it inevitable that pollution would increase. But he cautions that too many government ministries remain consumed by economic development. He says the government also needs to recognize the "environmental rights" of citizens.

"The pollution problem," he says, "is very serious."

Jim Yardley in Beijing

Jim Yardley is a correspondent in the Beijing bureau of The New York Times, with reporting by David Lague and Howard W. French.