Beijing smog alert turns 'orange' as air pollution soars
Beijingers have been warned to stay indoors as much as possible to avoid outdoor air pollution that has reached hazardous levels.
Particulate readings soared 15 times above the daily maximum recommended by the World Health Organization.
In response, city authorities have started using Beijing's new smog alert system - a series of emergency measures meant to quickly reduce pollution levels and protect city dwellers.
Beijing's alert level is now set to "orange", the second-highest level possible.
From China's capital, the BBC's Celia Hatton has more.