"On Scale of 0 to 500, Beijing’s Air Quality Tops ‘Crazy Bad’ at 755"
"BEIJING — One Friday more than two years ago, an air-quality monitoring device atop the United States Embassy in Beijing recorded data so horrifying that someone in the embassy called the level of pollution 'Crazy Bad' in an infamous Twitter post. That day the Air Quality Index, which uses standards set by the United States Environmental Protection Agency, had crept above 500, which was supposed to be the top of the scale."