Kai Ryssdal: Bejijng, China, has the world's second busiest passenger airport: 44 million people a year.
Except for the past couple of days. A combination of heavy smog and what the government is officially calling "fog" grounded hundreds of flights today. Thousands of passengers were left to their own devices.
But even if you weren't directly affected, Marketplace's Sarah Gardner reports the pollution there is starting to make its way here.
Sarah Gardner: The fog was so bad in northern China they closed down roads. Mix in Beijing's notoriously heavy smog, and China got a soupy brown haze that limited pilot visibility and made flying dangerous. One Chinese blogger said the skies got so dark, it looked like "the end of the world."
China scholar Elizabeth Economy says she's not surprised.
Elizabeth Economy: Frankly speaking, this has been taking place for over two decades now. They were closing the airport back in 1990 because of pollution levels.
But Economy says Chinese officials are under increasing fire for under-reporting pollution levels. The U.S. embassy is making its own measurements now, and U.S. scientists are delving into the impact of Asia's pollution on this country.
Dan Jaffe is an atmospheric scientist at the University of Washington.
Dan Jaffe: We now know that, especially along the West Coast, all the way from California and Washington to the Rocky Mountains, that Asia makes a significant contribution to the number of days that exceed the air quality standards.
Scientists believe Asia's contributing somewhere between 5 to 10 percent of the ozone in the U.S. And all our ozone adds up to $11 billion in yearly medical costs.
I'm Sarah Gardner for Marketplace.