The air quality in Beijing, China is notoriously bad, but it was unspeakably terrible over the weekend.

How bad was the pollution? On a scale of 0-500 (500 being the worst), Beijing hit 755 on Saturday evening. That's not a typo — Beijing's air was so bad that it shattered the existing scale.

That's according to the Beijing Air Monitor (@BeijingAir), a Twitter account run by the United States Embassy in Beijing that periodically tweets air sampling data from atop the embassy, per the New York Times.

01-12-2013 20:00; PM2.5; 886.0; 755; Beyond Index — BeijingAir (@BeijingAir) January 12, 2013

The air pollution level has since fallen to 152, which the account marks as "Unhealthy" based on Environmental Protection Agency standards.

A number on a scale is one thing, but what does it actually look like to be living in off-the-charts pollution? Bill Bishop, who writes for the Sinocism China Newsletter, tweeted this picture on Saturday:

Photo courtesy of Bill Bishop/Sinocism China Newsletter

The barely-seen object is the China World Trade Center Tower III, a 1,000-plus foot skyscraper that's one of the tallest in Beijing. Here's another picture of it Sunday, after pollution levels dropped somewhat:

Photo courtesy of Bill Bishop/Sinocism China Newsletter

Here's what it might look like on a comparatively normal day (it's the larger building on the left in the background):

Photo courtesy Flickr, bfishadow

What can Beijing do to help reduce its air pollution? What would you do if this were your city? Share in the comments.

Photo courtesy of Bill Bishop/Sinocism China Newsletter