China's air is notoriously polluted, full of gray smog that covers the sky.
The health problems associated with that pollution are the reason for 1.6 million deaths a year, or about 4,000 people a day.
But for a couple of weeks, the sky was bright blue.
In honor of a military parade to celebrate the 70th anniversary of the end of World War II, Beijing managed to clean up its air. They've done this before, notably in advance of the 2008 Summer Olympics.
Here's how they pulled it off.
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Here's how Beijing looked on a particularly high pollution day in August, exactly a month before the parade.
... And here's how the skies looked on the day of the parade, September 3. Residents nicknamed the color of the sky "parade blue."
China's had a pollution problem for years, as a result of rapid industrialization that started in the 1950s. In some areas, it's gotten so bad that its impact on your health is equivalent to smoking 40 cigarettes a day.
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