Thick smog in Beijing reaches dangerous levels
16 January 2014 Last updated at 12:13 GMT
Air pollution has reached dangerously high levels in the Chinese capital Beijing.
According to a monitoring post at the US embassy, the pollution was briefly more than 20 times higher than the amount considered safe by the World Health Organisation.
Officials advised people going to work to wear protective masks and children and the elderly to stay indoors.
Celia Hatton reports.