Toxic smog hangs over large swath of China

China is maintaining an orange alert for smog in Beijing. That means air pollution in the capital is at critical levels. Dense smog has pushed pollution to almost 18 times the World Health Organisation's guideline. Al Jazeera speaks with its correspondents Rob McBride in Tangshan, China and Harry Fawcett in Seoul, South Korea on the effects of the hazardous environment.