BEIJING — Last summer, Xu Demin struggled to cut emissions from his coal-fired factories as part of China's all-out effort to clean the air for the Beijing Olympics.
He could have simply waited six months. This spring, overseas demand for his farming and construction machinery plummeted, forcing him to close two plants and lay off 300 workers.
The global economic slowdown is helping to accomplish what some in China's leadership have tried to do for years: rein in the insatiable demand for coal-powered energy that has fed the country's breakneck growth but turned it into one of the world's most polluted nations.
Beijing, China's normally smog-choked capital, is breathing some of its cleanest air in nearly a decade, as pollution-control efforts get a sizable boost from a slowing economy.
"It's like the sky I saw overseas. I can see clouds. I've seen days here like I've seen in Europe or the U.S.," Xu says, his voice echoing in the cavernous space of his idle factory outside Beijing.
An Associated Press analysis of government figures backs up his observations: In the second half of last year, a period that included the Olympics in August, Beijing recorded its lowest air pollution readings since 2000, according to data from the Ministry of Environmental Protection.
The average monthly air pollution index was 74, about 25 percent lower than the previous seven years. Earlier data were not available.
Experts see several reasons for the improvement, including the relocation of some of Beijing's dirtiest factories outside the city and the partial continuation of traffic limits imposed for the Olympics.
Blue skies again
Perhaps most significant has been the economic downturn. Even elsewhere in China, where no Olympic pollution measures were imposed, the level of dirty air is down.
Chak Chan, who has published studies on China's air quality, warns the relief offered by the slump is temporary. "But if taken as an opportunity to do more in terms of energy efficiency and clean technology, then it can have a long-term effect in improving air quality," said Chan, a professor at Hong Kong University of Science and Technology.
For now, the cleaner air is a vindication of sorts for Beijing. China won its bid to host the Olympics partly on the promise that it would lead to a cleaner capital.
The government spent billions of dollars to clean up the air. It followed that spending with two months of drastic measures, temporarily shutting factories across five provinces, suspending construction in the capital, and ordering drivers to idle their cars every other day from July to September.
The results were dramatic, with air pollution index hitting record lows in August and September. Viewers around the world watched some sporting events take place under crystal blue skies.
In an assessment released in February, the U.N. Environmental Program said carbon monoxide levels fell 47 percent and sulfur dioxide 38 percent during the two-week Olympics. Even Beijing's worst pollutant — tiny particles of dust, soot and aerosol known as particulate matter 10 — was reduced by 20 percent. The U.N. report praised China for investing in long-term solutions such as public transport, urban parks and renewable-energy vehicles.
City officials also kept some traffic limits in place after the Olympics. Car owners are banned from driving one day a week, depending on their license plate numbers.
Air pollution, while not as low as in August and September when the harshest restrictions were in place, has remained far below recent years. From October through February, the average monthly pollution index was 82.
On a recent sunny morning, Li Heng, 66, joined dozens of seniors in Beijing's Ritan Park for a daily round of tai chi, the slow breathing exercises.
"I think the air is much better recently. We can take very deep breaths and the air feels fresh," he said, inhaling and exhaling loudly before thumping his chest.
It's not just Beijing. Southern China, home to many of the country's export-producing factories, has seen clear improvement.
Many cities in Guangdong province, where 62,400 businesses closed last year, have seen a drop in the number of badly polluted days, according to data on the Guangdong Provincial Environmental Protection Bureau Web site.
For example, the factory city of Dongguan reported more than a dozen days in the first half of 2008 when the air pollution index topped 100, a level considered unhealthy for sensitive groups including infants and the elderly. But in the second half of the year, there were only two such days.
Not all cities saw improvements. But across a sampling of seven key cities, the average number of badly polluted days halved between the first and second half of 2008.
A similar phenomenon was seen when the Soviet Union collapsed, causing the industrial haze over the Arctic to drop by nearly 50 percent, said Kenneth Rahn, an atmospheric chemist from the University of Rhode Island who has studied air quality in China.
"In principle, a reduction in economic activity can and will reduce air pollution," he wrote in an e-mail response. "I would expect something similar for China but of lesser magnitude."
During boom times, demand for electricity was so high in Guangdong's Pearl River Delta that companies often endured rotating blackouts. Some installed their own generators, which burned low-grade, dirty fuel.
But since last fall, blackouts have been few, and generators are seldom used.
Opportunity for greener technology
Environmental advocates say the downturn presents an opportunity for the government to move more aggressively to shut the dirtiest plants and enact stricter emissions regulations.
"The fact that the economy has slowed down has made it easier to stick to their plans to consolidate and close plants," said Deborah Seligsohn, director of the China climate program for the U.S-based World Resources Institute.
Seligsohn said she is encouraged by the fact that China's $586 billion economic stimulus plan includes funding for better technology and infrastructure that could benefit the environment.
In Guangdong, the slowdown could spur long-held plans to transform the region from dirty, labor-intensive manufacturing to cleaner high-tech industries.
Wang Xiaoming, director of communication for the Beijing Environmental Protection Bureau, said he hopes companies will take advantage of the slowdown to install more energy-efficient and cleaner technology.
"This period is an opportunity for each factory to adjust their production methods. If they were operating at full capacity, they would never have the time for this," he said.
It's advice that Xu, 59, has taken to heart as he seeks to reinvent Beijing Famed Machinery, his two-decade-old company.
With production down 75 percent this year, he has now decided to focus his energy on what had largely been a side project: making and selling machines that turn agricultural waste into what he calls "green coal" — fuel pellets that burn more cleanly than coal.
"It's up to us whether we can turn crisis into opportunity," he said. "This is a good time for our biomass product."
The longtime business owner even draws inspiration from the late founding father of communist China: "As Chairman Mao said, under certain circumstances, the bad thing can lead to a good result."
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