Year's worst pollution spell begins in northern cities

The view from a Beijing rooftop disappears as smog descends over the city on Dec 16. The Beijing municipal government has issued this year's first red alert for air pollution - effective from Friday evening – in response to severe smog forecast to blanket large areas of Beijing, Tianjin and Hebei, Henan and Shandong provinces in northern China until late Wednesday. [Photo/chinanews.com]