Coal blamed as China chokes on smog
31 January 2013 Last updated at 03:23 GMT
The Chinese government has warned residents of Beijing to keep their windows closed and stay indoors as pollution blighting the city worsens.
Coal consumption in the country has tripled in little more than a decade.
But that has contributed to thick and hazardous smog which some in Beijing say is the worst they can remember.
Martin Patience reports.