Anyone familiar with Beijing was quick to notice something was missing Monday, at least temporarily: the city's legendary smog.
We found out how the Chinese got rid of the pollution.
In order to host a summit focused on trade and economic growth, the capital of the world's second-largest economy was essentially shut down.
More than 4,000 factories have been ordered to halt production or cut back. Schools in the capital have been closed and cars have been taken off the road on alternating days. China's government has vowed to cut pollution here this week by as much as 40 percent.
Alvin Lin, with the U.S.-based Natural Resources Defense Council is working with China's government to reduce its reliance on coal, which accounts for up to 60 percent of air pollution here. He says Monday's blue skies are not a coincidence.
"No, this is mandated from the top," said Lin.
Last month, Beijing marathoners ran in hazardous smog. More than half of the days this year have been polluted enough to be a health hazard. Lin said he believes in China's long term promise to improve the air.
"I think the goal really is to ensure that this is the norm," he said. "You know that this is something people here can enjoy every day," in the long run. But in the short term, it took significant steps to accomplish.
China's President Xi Jinping called the skies "APEC blue." He acknowledged that while they're temporary he said through hard work they will be permanent.